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1

8. Pancreatic enzymes are involved in digestion of protein. They are released as proenzymes into
the duodenal lumen where they are activated.
The enzyme that plays an important role in activating the proenzymes is:

A. carboxypeptidase.
B. chymotrypsin.
C. elastase.
D. lipase.
E. trypsin.

Answer E. Trypsin

 

Chymotrypsin is converted to trypsin by small intestine enzyme enterokinase. Activated trypsin further activates chymotrypsin and other proteases.

 

2

12. A 2 year old boy is brought to the Emergency Department with a history of several days of rectal
bleeding. His mother first noticed reddish-coloured stools three days prior and since then has
changed a few nappies containing only blood. On examination the child is afebrile, alert and
playful and is eating well. He is tachycardic and abdominal examination is normal.
Which of the following investigations will most likely reveal the diagnosis?

A. Abdominal ultrasound.
B. Barium enema.
C. Gastroscopy.
D. Radionuclide scan.
E. Stool culture.

Answer D. Radionuclide scan.

Diagnosis in Meckel Diverticulum.

60% of complications arise in <2yr olds. Bleeding is painless. Diagnosed by 99m technetium pertechnetate (radionuclide) scan.

3

QUESTION 18
The initial luminal digestion of dietary starch by salivary and pancreatic amylase leads to the formation
of which disaccharide?


A. Fructose.
B. Galactose.
C. Glucose.
D. Maltose.
E. Sucrose.

Answer D. Maltose

Fructose, galactose and glucose are all monosaccharides. 

Starch breakdown forms maltose which is the equivalent of two units of glucose.

Sucrose is formed of glucose and fructose.

4

Centre for Disease Control (CDC) body mass index (BMI) charts have been recommended as a
screening tool to identify individuals who are overweight.
Which of the following BMI’s define a child likely to be obese?

A. >25 kg/m2
B. >30 kg/m2
C. >85th percentile for age.
D. >85th <95th percentile for age.
E. ≥95th percentile for age.

Answer E. ≥95th percentile for age.

>85th <95th percentile is overweight, >95th is obese

5

Infliximab is effective in the treatment of Crohn’s disease. Its mode of action involves:

A. binding to tumour necrosis factor.
B. blockade of tumour necrosis factor receptors.
C. blockade of tumour necrosis factor secretion from inflammatory cells.
D. enhancement of hepatic metabolism of tumour necrosis factor.
E. inhibition of tumour necrosis factor production

Answer A. binding to tumour necrosis factor.

6

A two-year-old boy presents with a six week history of diarrhoea and lethargy. Clinical examination
reveals lower limb and periorbital oedema. Investigations show:

Normal liver function tests apart from albumin 22 g/L [35 - 50 g/L].
Urine analysis was normal.
Coagulation profile was normal.
What faecal test would confirm that the low albumin was related to gastrointestinal losses?

A. Alpha-1 antitrypsin.
B. Chymotrypsin.
C. Elastase.
D. Proalbumin.
E. Trypsin.

Answer A. Alpha-1 antitrypsin.

Protein losing enteropathy

Children with protein losing enteropathy have severe protein loss through the gut, resulting in low plasma protein levels (hypoalbuminemia). Causes include hypertrophic gastritis (Ménétrier's disease), milk protein allergy, celiac disease, inflammatory bowel disease, giardiasis, intestinal lymphangiectasia, and right sided heart dysfunction (post-Fontan procedure).

Stool level of alpha-1 antitrypsin is an excellent screening test for protein losing enteropathy, as alpha-1 antitrypsin is a nondietary, serum protein synthesized in the liver. Its molecular weight of 50 kDa is similar in size to albumin (67 kDa), and it is resistant to intestinal and proteolytic digestion distal to the stomach.

7

Absorption of iron in the ferrous form (Fe 2+) occurs mainly in the:

A. stomach.
B. duodenum.
C. jejunum.
D. ileum.
E. colon

Answer B. duodenum

Most nutrients are absorbed in the duodenum  and proximal jejunum. Bile salts and vit B 12 are absorbed in the terminal ileum.

Water is absorbed throughout the small intestine.

8

In infants with glucose-galactose malabsorption, ingestion of foods containing which of the following
carbohydrates is likely to cause severe diarrhoea and dehydration?

A. Fructose.
B. Mannitol.
C. Mannose.
D. Sorbitol.
E. Sucrose.

Answer E. Sucrose

Sucrose is a disaccharide  which is broken down by sucrase to form glucose and fructose.

Sorbitol is a sugar alchohol obtained by the reduction of glucose.

 

Glucose + glucose = maltose

Glucose + galactose = lactose

Glucose + fructose = sucrose

Fructose + galactose = lactulose

9

Which of the following lipid-lowering drugs works primarily by the upregulation of low density
lipoprotein (LDL) receptor activity?

A. Cholestyramine.
B. Clofibrate.
C. Colestipol.
D. Nicotinic acid.
E. Simvastatin.

Answer E. Simvastatin.

Simvastatin is a HMG CoA reductase inhibitor leading to upregulation of LDL receptors in the liver, in turn increasing catabolism of plasma LDL and lowering plasma concentration.

Cholestyramine and colestipol are resins that bind with bile acids and are excreted in faeces.

Clofibrate promotes conversion of VLDL to LDL, reducing VLDL levels.

Nicotinic acid inhibits the synthesis of VLDL.

 

10

What is the commonest cause of failure to thrive in infancy in developed countries?

A. Chronic organ failure.
B. Gastrooesophageal reflux.
C. Inadequate intake.
D. Malabsorption.
E. Recurrent infection.

Answer C. Inadequate intake.

11

A four-year-old boy was playing with his brother and accidentally swallowed a coin. Initially there was
some coughing and spluttering but he subsequently settled. An X-ray taken at the Emergency
Department four hours later shows the coin to be at the lower oesophagus just above the
gastrooesophageal junction. What is the most appropriate next step?

A. Barium swallow.
B. Domperidone.
C. Endoscopic removal.
D. Oral fluid bolus.
E. X-ray in 48 hours.

Answer C. Endoscopic removal

According to Up To Date....if object has not passed out of oesophagus by 24 hours, should be removed endoscopically. 

If patient is symptomatic or duration is unknown, should be removed immediately.

12

An eight-week-old ex-premature baby with congenital hypothyroidism fails to respond to an adequate
dose of thyroxine given regularly. The baby is breast fed and is on nutritional supplements. Which of
the following nutritional supplements is most likely to affect absorption of thyroxine?
A. Folic acid.
B. Iron.
C. Phosphate.
D. Vitamin A.
E. Vitamin D.

Answer B. Iron.

 

13

A 14-year-old has recently been diagnosed with anorexia nervosa. She has a body mass index (BMI)
of 15 kg/m2. She was commenced on nasogastric feeds. The level of which of the following
electrolytes is most likely to fall if calories are given too rapidly?

A. Calcium.
B. Chloride.
C. Magnesium.
D. Phosphate.
E. Sodium.

Answer D. Phosphate

Refeeding Syndrome

In significantly malnourished patients, the initial stage of oral, enteral, or parenteral nutritional replenishment causes electrolyte and fluid shifts that may precipitate disabling or fatal medical complications. The refeeding syndrome is marked by:

  • Hypophosphatemia
  • Hypokalemia
  • Hypomagnesemia
  • Vitamin (eg, thiamine) and trace mineral deficiencies
  • Volume overload
  • Edema

Hypophosphatemia is the hallmark of the syndrome and predominant cause of the refeeding syndrome.

The pathogenesis of hypophosphatemia begins when stores of phosphate are depleted during episodes of AN and starvation. When nutritional replenishment begins and patients are fed carbohydrates, glucose causes release of insulin, which triggers cellular uptake of phosphate (and potassium and magnesium). Insulin also causes cells to produce a variety of depleted molecules that require phosphate (eg, adenosine triphosphate (ATP) and 2,3-diphosphoglycerate), which further depletes the body’s stores of phosphate. The lack of phosphorylated intermediates causes tissue hypoxia and resultant myocardial dysfunction and respiratory failure.

14

A 16-year-old female was diagnosed with ulcerative colitis at the age of 12. Her disease was fairly
well controlled, initially with steroids and subsequently on maintenance salazopyrine. Over the last six
months she complained of poor concentration, tiredness and vague upper abdominal pain. Blood
investigation done by her general practitioner showed:

Alanine aminotransferase (ALT) 80 IU/L [<55 IU/L]
Alkaline phosphatase (ALP) 660 IU/L [30 - 120 IU/L]
Gamma glutamyltransferase (GGT) 332 IU/L [0 - 40 IU/L]
Total Bilirubin 6 μmol/L [<8 μmol/L]
Antinuclear antibody (ANA) + ve (titre 1:80)
Anti-smooth muscle antibody –ve
Anti-liver kidney microsomes –ve
What condition does this patient most likely have?

A. Autoimmune hepatitis.
B. Cholelithiasis.
C. Non-alcoholic steatohepatitis (NASH).
D. Sclerosing cholangitis.
E. Viral hepatitis.

Answer D. Sclerosing cholangitis

Patients with UC are at risk of developing sclerosing cholangitis. Half of patients are asymptomatic. Fatigue and pruritis most common symptoms.

Lab tests show a cholestatic picture, with raised ALP predominant, and fluctuating GGT due to transient blockage. AST and ALT are usually <300. Anti ANA and anti SMA antibodies may also be raised.

Autoimmune hepatitis

Type 1 (classic) - raised ANA &/or SMA

Type 2 - Anti LKM (Liver/Kidney microsomal antibody)

Cholelithiasis

Patients often asymptomatic, may present with biliary colic, normal physical exam and normal lab results. Pts might c/o diaphoresis, N&V.

NASH

Hepatic inflammation that histologically is indistinguishable from alcoholic steatohepatitis. Most patients are asymptomatic. Some may c/o fatigue, malaise, and vague right upper abdominal discomfort. LFTs may indicate raised AST and ALT.

Viral Hepatitis

Pts with viral hepatitis present more acutely with jaundice a predominant feature. In viral hepatitis, raised autoantibodies not a typical feature. Most liver enzymes will be raised.

15

A term born infant presents to the Emergency Department at five days of age with a six hour history of
bilious vomiting. The parents report that he passed a normal stool 12 hours beforehand. On
examination, he has mild abdominal distension and his perfusion is decreased, with a capillary refill
time of three seconds. Plain abdominal X-ray is normal.
Which of the following investigations is most likely to be diagnostic?

A. Abdominal ultrasound.
B. Air enema.
C. Barium enema.
D. Barium meal.
E. Computed tomography scan of the abdomen.

Answer D. Barium Meal

Presentation is likely to be a volvulus or obstruction. Barium meal is best way to diagnose. Air enema is diagnosic and therapeutic for intussusception. Barium enema for Hirschsprungs disease. CT is not indicated as first line.

16

A two-year-old boy was brought to the Emergency Department after he passed a large amount of
blood per rectum. He was a previously healthy boy and on clinical examination he appeared pale but
alert. He was not in any distress, his heart rate was 160 beats/minute and his systolic blood pressure
was 70 mmHg. Examination revealed a soft but mildly distended abdomen. There was no localised
tenderness or palpable mass. He continued to pass maroon coloured clots during the examination.
Initial haemoglobin was 70 g/L [105 – 135 g/L].
What is the most likely diagnosis?

A. Allergic colitis.
B. Duodenal ulcer.
C. Intussusception.
D. Meckel diverticulum.
E. Rectal polyp.

Answer D. Meckel Diverticulum.

Meckels is associated with painless PR bleeding in an otherwise well child.

Allergic colitis occurs in infancy with similar presentation of blood tinged or mucousy stools in otherwise well baby. Duodenal ulcer presents with pain and possibly malena. Intussusception has bouts of severe pain, mass in the abdomen and assoc with red current jelly stool if severe/late stage. Rectal polyp assoc with pain, constipation, diarrhoea and bleeding.

17

A six-month-old infant drinks 1000 ml of a standard cow milk formula daily. Approximately how much
energy does the child get per day from his milk intake?

A. 200 kcal (840 kJ)
B. 500 kcal (2100 kJ)
C. 670 kcal (2820 kJ)
D. 810 kcal (3400 kJ)
E. 1000 kcal (4200 kJ)

Answer C. 670 kCal (2820kJ)

Standard formulas provide approx 280kJ/100mL (67 kCal)and 1.5g protein per 100ml.

Energy requirments at 0-6 months 115kcal/kg/day, 6-12 months 95kcal/kg/day.

18

A 15-year-old boy presents with dysphagia and regurgitation of undigested food. His barium swallow images are shown below.

 

What is the most likely diagnosis?
A. Achalasia.
B. Eosinophilic oesophagitis.
C. Peptic stricture.
D. Tracheo-oesophageal fistula.
E. Vascular ring.

Answer A. Achalasia

Primary achalasia is a disease of unknown etiology in which there is a loss of peristalsis in the distal esophagus and a failure of lower esophageal sphincter (LES) relaxation with swallowing (main cause of symptoms). Can occur at any age, before adolescence is rare.

Barium swallow will show 

  • Dilation of the esophagus
  • Narrow esophagogastric junction with "bird-beak" appearance caused by the persistently contracted LES 
  • Aperistalsis
  • Poor emptying of barium

Eosinophilic Oesophagitis

Ring-like areas of narrowing on barium swallow

TOF

Presents with coughing/aspiration symptoms in infancy.

Vascular Ring

Vascular rings are congenital anomalies of the aortic arch that result in compression of the tracheobronchial tree and/or esophagus, leading to respiratory and gastrointestinal symptoms. Barium swallow demonstrates a posterior indentation of the esophagus in all vascular rings except for the pulmonary sling, in which an anterior indentation and increased space between the trachea and esophagus are found.

19

Malrotation with midgut volvulus is a potentially life threatening condition in otherwise healthy infants. Which of the following best describes the normal rotation of the bowel that occurs during embryogenesis?

A. Clockwise 180 degrees.
B. Clockwise 270 degrees.
C. Counterclockwise 90 degrees.
D. Counterclockwise 180 degrees.
E. Counterclockwise 270 degrees. 

Answer E. Counterclockwise 270 degrees. 

20

The addition of starch to oral rehydration solution increases water absorption by which mechanism?

A. Aquaporin transport.
B. Colonic fermentation.
C. Enterohepatic reabsorption.
D. Sodium-glucose co-transport.
E. Sodium-Potasium ATPase. 

B. Colonic fermentation.
The sodium coupled co-transport with glucose is the basis of ORT as it drags water along behind it. Addition of resistant starch to ORS increases colonic fermentation (bacteria break starch down to short chain fatty acids). The colon which was unable to absorb water can do so with via short chain fatty acis.

21

In which segment of the gastrointestinal tract is most of dietary iron absorbed?

A. Distal ileum.
B. Duodenum.
C. Jejunum.
D. Proximal ileum.
E. Stomach. 

B. Duodenum
Iron and Folate are absorbed in the duodenum and Vit B12 is absorbed in the terminal ileum.

22

Supplementation with which of the following micronutrients has been shown to be most effective in the treatment of chronic diarrhoea in malnourished children?

A. Cyanocobalamin.
B. Folic acid.
C. Iron.
D. Magnesium.
E. Zinc. 

E. Zinc.
Zinc reduces severity and duration of persistent diarrhoea and recommended by WHO to be supplemented in diarrhoeal illness in developing countries. Also noted to decrease severity and duration in acute diarrhoea.

23

The optimal method of rehydration in children with gastroenteritis is widely accepted to be through the use of Oral Rehydration Solution because it optimises the absorption of both water and electrolytes in appropriate quantities. 

Which of the following best describes the mechanism by which water is absorbed from the
gastrointestinal lumen?

A. Activation of adenylate cyclase.
B. Active transport via sodium - glucose cotransporter.
C. Active transport via sodium - water cotransporter.
D. Passive diffusion across an osmotic gradient.
E. Utilisation of sodium - potassium ATPase pump. 

Answer D. Passive diffusion across an osmotic gradient.

Water absorption is passive depending upon the osmotic gradient that is dictated by sodium transport via the following three principal mechanisms:

  • Na/H exchangers
  • Electrochemical gradient
  • Sodium-coupled transport with carrier organic solutes (eg, glucose)
     

24

Which vitamin B complex nutritional deficiency is most likely to cause angular cheilosis and glossitis?

A.  Cobalamin.
B.   Folate.
C.   Niacin.
D.   Riboflavin.
E.   Thiamin.

Answer D. Riboflavin

  • Cobalamin (B12) Irritability, hypotonia, developmental delay, developmental regression, and involuntary movements. Hyperpigmentation of knuckles and palms.
  • Folate - megaloblastic anemia and hypersegmentation of neutrophils. Nonhematologic manifestations include glossitis, listlessness, and growth retardation.
  • Niacin (B3) - Pellagra (the 4 D’s - diarrhoea, dermatitis, dementia and death).
  • Riboflavin - (B2) - cheilosis, glossitis, keratitis, conjunctivitis, photophobia, lacrimation, corneal vascularization, and seborrheic dermatitis.
  • Thiamin - (B1) - Peripheral neuritis, decreased DTR, loss of vibration sense, cramping legs.

25

According to the  diagram shown above, the most common type of oesophageal atresia is:

A. a.
B. b.
C. c.
D. d.
E. e. 

Answer A. a.
Oesophageal atresia with distal tracheoesophageal fistula accounts for 84%. Type C next most frequent (8%) with oesophageal atresia without tracheoesophageal fistula.

26

Which of the following nutrients is predominantly absorbed in the duodenum and upper small
intestine?

A. Bile salts.
B. Calcium.
C. Linoleic acid.
D. Vitamin B12.
E. Vitamin E. 

Answer B. Calcium
Bile salts and B12 absorbed in distal ileum. Calcium - duodenum. Linoleic acid ??, Vitamin E ??

27

In infants with glucose-galactose malabsorption, ingestion of foods containing which of the following carbohydrates is likely to cause severe diarrhoea and dehydration?

A. Fructose. 
B. Mannose.
C. Mannitol.
D. Sorbitol.
E. Sucrose.

Answer E. Sucrose
Sucrose is a disaccharide  which is broken down by sucrase to form glucose and fructose.
Sorbitol is a sugar alchohol obtained by the reduction of glucose.

Glucose + glucose = maltose
Glucose + galactose = lactose
Glucose + fructose = sucrose
Fructose + galactose = lactulose
 

28

A four-week-old boy presents with persistent abdominal distension and infrequent bowel motions. He is exclusively breast-fed but is vomiting after most feeds. His weight gain is slow. On rectal examination he empties faecal fluid and air under pressure. An abdominal X-ray shows occasional small intestinal air-fluid levels and a distended colon. 
Which diagnostic test will most likely reveal the correct diagnosis?

A. Barium meal.
B. Computed tomography scan.
C. Gas enema.
D. Nuclear medicine intestinal transit scan.
E. Rectal suction biopsy. 

E. Rectal suction biopsy. 

 

29

A three-month-old male boy presents with a four week history of persistent crying and frequent vomiting after most feeds. The infant is predominantly breast-fed. Occasional supplemental cow milk formula feeds were commenced from eight weeks of age because his mother returned to part-time work.  The infant is generally well and passes four soft bowel motions per day, with increased mucus but no visible blood. Over the past two months his weight has fallen from the 50th to the 25th weight-for-age percentile. 

Which one of the following is the most likely diagnosis?

A. Cow milk protein intolerance.
B. Gastro-oesophageal reflux.
C. Infantile colic.
D. Lactose intolerance.
E. Pyloric stenosis. 

Answer A CMPI.

These infants are generally healthy but pass blood-tinged stools and mucus; some may be fussy or have increased frequency of bowel movements, but frank diarrhea is not typical. Indeed, the parent usually reports that "aside from the diaper", the child is well. The disorder typically presents between two and eight weeks of age, although there may be a history of bleeding several weeks prior to diagnosis that may have been erroneously attributed to anal fissures. Presentation as early as the first week of life has been described. With complete elimination of the offending protein from the mother's diet or formula, clinical bleeding typically clears within three days.

30

A six-year-old girl is referred with poor weight gain and chronic diarrhoea. Which of the following has the highest positive predictive value for coeliac disease?

A.  IgA AGA (Immunoglobulin A Antigliadin Antibody).  
B.  IgG AGA (Immunoglobulin G Antigliadin Antibody). 
C.  IgA AntiTTG (Immunoglobulin A Anti Tissue Transglutaminase). 
D.  IgG AntiTTG (Immunoglobulin G Anti Tissue Transglutaminase).
E.  HLA (Human Leucocyte Antigen) DQ2 Typing. 

Answer C.  IgA AntiTTG (Immunoglobulin A Anti Tissue Transglutaminase).

31

A four-week-old breast-fed infant presents with a one week history of persistent rectal bleeding. The infant has passed three to four mustard coloured stools per day, containing some mucus and streaks of bright red blood. Defaecation is often associated with increased straining and unsettled behaviour. The infant is otherwise well and thriving. 
What is the most likely diagnosis?

A. Allergic proctocolitis.
B. Anal fissure.
C. Bacterial gastroenteritis.
D. Juvenile polyp.
E. Necrotising enterocolitis. 

Answer A. Allergic proctocolitis

Allergic proctocolitis presents b/w 2 and 8 weeks age in an otherwise well infant. Infants pass blood tinged stools with mucus, but not usually frank diarrhoea. Anal fissure associated with large stools, chronic diarrhoea and painful defacation. Not associated with mucus. Clinical features of bacterial gastroenteritis are fever with bloody, mucousy diarrhoea. Juvenile polyps occur in children between ages of 2 and 8 years, with a peak at 3-4 years and PR bleeding is painless. NEC would present with a sick infant with distended abdomen with systemic signs of illness. Usually occurs in preterm neonates, but can occur in term neonates. 

32

A four-week-old male infant presents with a left-sided chylothorax following aortic coarctation repair. The chylothorax responded well to drainage and total parenteral nutrition. Oral feeds are recommended. 
Which of the following nutrients should be avoided to prevent re-accumulation of the effusion?

A. Carbohydrates.
B. Cholesterol.
C. Long chain triglyceride.
D. Medium chain triglyceride.
E. Protein. 

Answer C. Long chain triglyceride

The use of formula with a high concentration of medium chain triglycerides (MCT) and a low concentration of long chain fatty acids has been shown to be effective in decreasing chyle flow with resolution of chylous effusions.

33

 A six-year-old boy with Down syndrome presents to your practice with persistent diarrhoea for the past four weeks. Stool microscopy reveals the following findings:

   Fat globules:    +
   Fatty acid crystals:  +++
   Red blood cells:    0
   White blood cells:   0
   Faecal pH:     5.5   [> 6.5]
   Reducing sugars:   1%   [< 0.25%]

What is the most likely diagnosis?

A. coeliac disease.
B. cow's milk enteropathy.
C. crohn disease.
D. infectious colitis.
E. lactose intolerance.

Answer A. Coeliac disease.

There is a strong association between coeliac disease and DS. The stool shows a general picture of malabsorption. The absence of RBCs and WBCs makes Crohns disease and infectious colitis unlikey. 

Fat globules indicate malabsorption. Consider CF and Shwachman-Diamond in ddx.

Acidic stool due to carbohydrate malabsorption and reducing sugars. 

Reducing sugars present with carbohydrate malabsorption.

Fatty acid crystals indicate intestinal damage.

34

A two-year-old boy presents with a four week history of persistent diarrhoea and mild weight loss. He has recently commenced childcare. Stool microscopy and biochemistry reveal the following:

Fatty acid crystals   +++
Fat globules     +
Red blood cells     Not detected
White blood cells    Not detected  
Giardia trophozoites   Not detected
Giardia cysts     Not detected
Stool pH      5.5    [>6]
Reducing sugars    0.5%    [<0.25]
Total sugars     0.5%    [< 0.25]

Which of the following is the most likely diagnosis?

A. Bacterial gastroenteritis.
B. Coeliac disease.
C. Cryptosporidiosis.
D. Lactose intolerance.
E. Viral gastroenteritis. 

Answer B. Coeliac Disease

Fat globules indicate malabsorption and fatty acid crystals are from intestinal damage. Acidic stool from carbohydrates and reducing substances (both of which are positive). Carbohydrates cannot be absorbed because of damage at the brush border where lactase, maltase and isomaltase sit. The sugars are then transported to the large bowel where they become fermented and cause acidic stool.

Bacterial gastroenteritis you would expect faecal leukocytes, but not with viral. (also seen with parasites).

In viral gastro, you may see acidic stool and reducing substances due to damage to the brush border. 

The chronic picture (4 weeks) + weight loss in this child makes coeliac disease the most likely diagnosis.

35

QUESTION 37
Apart from glucose, which other carbohydrate is absorbed by the intestinal sodium-glucose transporter 1 (SGLT-1)?

A. Fructose.
B. Galactose.
C. Lactose.
D. Mannose.
E. Sorbitol. 

Answer B. Galactose

Glucose and galactose are co-transported with the active transport of Sodium via the SGLT-1 transporter. 80% of carbohydrate intake is a starch and the final product of which is glucose. Remaining 20% made up of galactose (absorbed almost exactly same as glucose) and fructose. Fructose is transferred by facilitated diffusion thru intestinal epithelium. It is phosphorylated and converted to glucose for transport in the blood. Because it is not transported with sodium, its rate of transport is about 1/2 that of glucose and galactose.

Most carbohydrates are absorbed as monosaccharides which include glucose, galactose and fructose.

Glucose + glucose = maltose
Glucose + galactose = lactose
Glucose + fructose = sucrose
Fructose + galactose = lactulose

36

Which of the following nutrients is predominantly absorbed in the duodenum and upper small intestine?


A. Bile salts.
B. Calcium.
C. Linoleic acid.
D. Vitamin B12.
E. Vitamin E. 

Answer B. Calcium

Bile salts and B12 absorbed in distal ileum.

Calcium - duodenum.

Linoleic acid ??, Vitamin E ??

37

A breast-fed six-month-old boy presents with abdominal distension, loose stools up to six times daily and failure to thrive. He appears to be feeding well. His neonatal metabolic screening tests are all unremarkable. His full blood examination and liver function tests are normal. Faecal microscopy findings are shown below:
Fat globules:   +++
Fatty acid crystals:  negative
Red blood cells:  negative
White blood cells:  negative
Chymotrypsin:   negative
What is the most likely diagnosis?

A. Chronic liver disease.
B. Cystic fibrosis.
C. Food allergy.
D. Gastroenteritis.
E. Lymphangiectasia.

Answer B. Cystic Fibrosis

Fat globules in stool are due to malabsorption.

Many causes of malabsorption including pancreatic insufficiency.

Cystic Fibrosis causes pancreatic insufficiency which can present as frequent, bulky, foul-smelling stools which may be oily.

If not detected in newborn screen, infants usually present due to failure to thrive.

Abdominal distention may also be present.

 

 

38

QUESTION 67
Which biochemical abnormality is typical for the 'refeeding syndrome' which occurs due to the reintroduction of food after a period of prolonged undernutrition?

A. Hypercalcaemia.
B. Hyperphosphataemia.
C. Hypocalcaemia.
D. Hypophosphataemia.
E. Hypotriglyceridaemia. 

Answer D. Hypophosphataemia

Phosphate stores are depleted during starvation. Nutritional replenishment with carbohydrates (glucose) releases insulin which triggers cellular uptake of phosphate.

39

A previously well 13-year-old boy presents for investigation of persistent lip swelling and bleeding gums for the past four months. For about 12 months he has experienced colicky abdominal pains after eating. He has had no vomiting or diarrhoea but complains of pain on defaecation, with some bright red blood on the toilet paper. He has lost 3 kg in weight over the past six months. On examination he looks pale and has marked gingivitis and swollen upper and lower lips. His abdomen is soft, without palpable organomegaly, but with mild tenderness and fullness in the right iliac fossa. He has a perianal skin tag.
What is the most likely diagnosis?

A. Chronic granulomatous disease.
B. Crohn's disease.
C. Gastrointestinal tuberculosis.
D. Sarcoidosis.
E. Systemic lupus erythematosus.

Answer B. Crohn’s disease

Most common intestinal manifestations are abdominal pain weight loss, diarrhea, hematochezia (fresh blood from anus), and growth failure.

Extraintestinal manifestations of CD may involve the skin, joints, liver, eye, and respiratory system.

Perianal disease includes skin tags, fissures, fistulas and abscesses.

Oral lesions occur in up to 40 percent of children with Crohn’s disease, and may include mucogingivitis, aphthous ulcers, or swelling.

Chronic granulomatous disease may present with oral changes including gingivitis, stomatitis, aphthous ulcerations, and gingival hypertrophy. CGD is associated with IBD with 20% diagnoses with UC or CD. The stem does not mention other features that you would expect in CGD.

Abdominal TB - nonspecific chronic abdo pain most common symptom. Anorexia, fatigue, fever, night sweats, weight loss, diarrhea, constipation, or blood in the stool may be present. Palpable RLQ mass in 25-50% patients. TB may be associated with ascites which is uncommon in CD.

Sarcoidosis is a systemic granulomatous disease. Abdominal involvement typically manifests as gastric ulceration with colicky, epigastric and periumbilical abdominal pain. Nonbloody diarrhea generally is the most common symptom. Weight loss, anorexia, low-grade fever, and weakness may be present.

Abdominal involvement in SLE is usually secondary to medications - gastritis and peptic ulcers.

40

In the treatment of patients with anorexia nervosa, the administration of nocturnal nasogastric feeds to supplement a normal meal plan has been shown to:

A. increase long-term weight gain.
B. increase short-term weight gain.
C. make no difference to weight gain.
D. reduce long-term weight gain.
E. reduce short-term weight gain.

Answer B. increase short-term weight gain.

41

QUESTION 67
The mother of a four-week-old boy is concerned that her infant has small streaks of bright red blood and mucus in his stools. The infant is entirely breast-fed and otherwise well. The physical examination is unremarkable.
What is the most likely diagnosis?

A. Allergic proctocolitis.
B. Anal fissure.
C. Duplication cyst.
D. Gastroenteritis.
E. Rectal polyp.

Answer A. Allergic proctocolitis

Allergic proctocolitis is usually due to cow or soy milk and can occur in breastfed infants due to milk in mothers diet. Infants are otherwise completely well with streaks of blood and mucous in the stool.

Anal fissure most common cause of haematochezia in infants <1 yr. Usually associated with straining and painful defecation with bright red blood streaks on stool surface.

Duplication cysts is a rare cause of lower GI bleeding that may be associated with abdominal pain, palpable mass and may be lead point for intussusception.

Gastroenteritis is associated with diarrhoea, vomiting, fever, anorexia, myalgia, abdominal cramps and headache. Blood and mucous in the stool associated with bacterial or parasitic gastroenteritis, almost never with viral.

Bacterial gastroenteritis most common in ages 2-4 and in those with travel history or farm exposure.
Viral gastroenteritis most common in children aged <2 yrs and stools are loose and watery, up to ~20 per day.

Juvenile polyps can cause painless rectal bleeding and typically present after 2-8 yrs age, most at 3-4 yrs.

42

A six-year-old boy with Down syndrome presents to your practice with persistent diarrhoea for the past four weeks. Stool microscopy reveals the following findings:
Fat globules:   +
Fatty acid crystals:  +++
Red blood cells:  0
White blood cells:  0
Faecal pH:   5.5  [> 6.5]
Reducing sugars:  1%  [< 0.25%]

What is the most likely diagnosis?
A. Coeliac disease.
B. Cow's milk enteropathy.
C. Crohn disease.
D. Infectious colitis.
E. Lactose intolerance.

Answer A. Coeliac disease.
There is a strong association between coeliac disease and DS. The stool shows a general picture of malabsorption. The absence of RBCs and WBCs makes Crohns disease and infectious colitis unlikey. 
Fat globules indicate malabsorption. Consider CF and Shwachman-Diamond in ddx.
Acidic stool due to carbohydrate malabsorption and reducing sugars. 
Reducing sugars present with carbohydrate malabsorption.
Fatty acid crystals indicate intestinal damage.

43

A five-year-old boy presents with multiple ulcerated skin lesions (as shown) with raised margins, which commenced as pustular lesions associated with fever a week prior to presentation. Pyoderma gangrenosum is confirmed by skin biopsy. Which of the following is most likely to be associated with this skin lesion?

A. Chronic granulomatous disease.
B. Human immunodeficiency virus (HIV) infection.
C. Inflammatory bowel disease.
D. Pseudomonas septicaemia.
E. Systemic lupus erythematosis.

Answer C. Inflammatory bowel disease.

1/2 of pts with pyoderma gangrenosum have underlying systemic disease, most commonly inflammatory bowel disease, haematological disorders and arthritis.

44

A six-year-old patient with coeliac disease undergoes dual sugar intestinal permeability testing.  Two sugars, rhamnose and lactulose, are administered orally and the subsequent urinary excretion is measured over five hours.  Rhamnose is actively absorbed by the small intestinal villus, whereas lactulose is absorbed via passive paracellular transport. 

Which of the following findings in urine indicate poor adherence to a gluten-free diet? 
 

Answer B. Rhamnose decreased, lactulose normal

Rhamnose absorption in decreased due to damage to small intestinal villi, lactulose continues to be absorbed by passive transport as this is not affected by damage caused by gluten.

45

A five-week-old male infant presents with a ten-day history of increasing vomiting and poor weight gain. Serum electrolytes and a venous blood gas show:
 
sodium   128 mmol/L   [133-143]
potassium   2.7 mmol/L   [3.8-6.0]
chloride   66 mmol/L   [95-110]
urea    16.3 mmol/L  [1.0-6.0]
creatinine   78 µmol/L   [20-50]
glucose   4.0 mmol/L   [3.5-5.5]

pH    7.62    [7.36-7.44]
pCO2    69 mmHg   [35-45]
bicarbonate   58 mmol/L   [18-24]
base excess  +6.2 mmol/L  [0-2.0]

What is the most likely diagnosis?

A. Congenital adrenal hyperplasia.
B. Gastroenteritis.
C. Gastro-oesophageal reflux.
D. Paracetamol toxicity.
E. Pyloric stenosis. 

Answer E. Pyloric Stenosis

Venous gas shows hypokalemic, hypochloremic alkalosis, the classic finding in pyloric stenosis. Bicarbonate is high because hypokalemia triggers active resorption of bicarbonate, and chloride is required as a co-transporter to excrete bicarbonate in the renal tubules.

CAH is an adrenal insufficiency with similar presentation to pyloric stenosis, but with hyperkalemic acidosis.

46

Glucokinase plays a critical role in the beta cell of the pancreas.  Which of the following reactions is primarily controlled by the enzyme glucokinase?

A. Hydrolysis of glucose-6-phosphate to free glucose.
B. Opening of the sulphonylurea channel.
C. Oxidation of glutamate to alpha-ketoglutarate.
D. Phosphorylation of glucose to glucose-6-phosphate.
E. Sequestering of glucose transporter-2 (GLUT-2) receptors on the cell surface. 

Answer D. Phosphorylation of glucose to glucose-6-phosphate.

Glucokinase acts as glucose sensor in pancreatic beta cells. It phosphorylates glucose to glucose-6-phosphate. Mutations in this process lead to a type of MODY.

47

A three-year-old boy is brought to the emergency department with alcohol intoxication following a family party at home.  Which of the following best describes the primary hepatic metabolic pathway for alcohol?

A. Conjugation with glucuronic acid.
B. Oxidation by alcohol dehydrogenase.
C. Oxidation by peroxisomal catalase.
D. Oxidation by the microsomal ethanol-oxidizing system (MEOS).
E. Reduction using nicotinamide-adenine dinucleotide phosphate (NADPH) as a cofactor.

Answer B. Oxidation by alcohol dehydrogenase

Alcohol is metabolised by several pathways. The primary hepatic pathway involves oxidation of ethanol by alcohol dehydrogenase to form acetaldehyde with NAD+ as a byproduct.

Acetaldehyde is then further oxidised by acetaldehyde dehydrogenase to form acetate with NADH as a byproduct.

48

Microscopy of a stool sample from a six-month-old infant with persistent diarrhoea reveals the
following findings:

red blood cells     negative
white blood cells    negative
fatty acid crystals    +++
fat globules     negative

Which of the following is the most likely diagnosis?

A. Bacterial gastroenteritis.
B. Cow’s milk-sensitive enteropathy.
C. Cystic fibrosis.
D. Intestinal lymphangiectasia.
E. Liver cirrhosis. 

Answer B. Cow’s milk-sensitive enteropathy

Presence of fatty acid crystals indicates mucosal damage as found in cow’s milk enteropathy.
Absence of fat globules (ie malabsorption) make CF unlikely.

49

Oral rehydration solution facilitates increased net water absorption by which mechanism?

A Activation of aquaporins.
B. Intestinal transcytosis.
C. Osmotic gradient.
D. Sodium-glucose co-transport.
E. Sodium-potassium (Na+-K+) ATPase. 

Answer D. Sodium-glucose co-transport

Water absorption is passive depending upon the osmotic gradient that is dictated by sodium transport via the following three principal mechanisms:

  • Na/H exchangers
  • Electrochemical gradient
  • Sodium-coupled transport with carrier organic solutes (eg, glucose)

50

Omeprazole affects gastric parietal cell function by inhibition of which pathway?

A. Gastrin receptors.
B. Histamine-2 receptors.
C. Hydrogen-potassium (H+-K+ ) ATPase.
D. M1 muscarinic receptors.
E. Prostaglandin E2. 

Answer C. H+/K+ ATPase

51

A five-year-old boy presents with persistent diarrhoea and weight loss. Stool electrolytes and pH are as follows:

sodium     98 mmol/L 
potassium    22 mmol/L
pH      6.5      [≥ 6.5]

Which of the following is the most likely diagnosis?

A. Coeliac disease.
B. Cryptosporidiosis.
C. Giardiasis.
D. Lactose intolerance.
E. Laxative abuse.

Answer B. Cryptosporidiosis

  • Stool osmotic gap= 290 -2x(stool Na+ + K+)
  • Normal gap is 50-100
  • Low osmotic gap (<50) - secretory diarrhoea
    • toxin mediated
  • High osmotic gap (>100) - osmotic diarrhoea
    • coeliac sprue, chronic pancreatitis, lactase def, laxative abuse, lactulose

52

A four-year-old boy is evaluated by his paediatrician because of asymptomatic and persistent
elevation of serum aminotransaminases to three to four times above the normal range.  The initial blood tests are taken following an acute episode of gastroenteritis.  The serum aminotransaminases are elevated without an increase in the bilirubin or biliary derived enzymes over a six-month period. The child’s past history is unremarkable.
Which of the following investigations may be helpful in the further evaluation of the cause of the serum abnormalities?

A. Coagulation profile.
B. Creatine kinase.
C. Endoscopic retrograde cholangiopancreatography (ERCP).
D. Serological tests for hepatitis A.
E. Ultrasound of the liver.

Answer B. Creatine kinase.
? looking for muscle disorder.

53

A mother notices low-grade rectal bleeding in her breast-fed daughter. The 
three-week-old infant passes four to five semi-formed stools per day with visible streaks of blood and some mucus. The infant is well and thriving. 

What is the most likely diagnosis?

A Anal fissure.
B. Bacterial gastroenteritis.
C. Food protein proctocolitis.
D. Juvenile polyp.
E. Swallowed maternal blood. 

Answer C. Food protein proctocolitis

3 week old infant passing semi formed stools unlikely to have anal fissure (straining, difficulty passing, painful defacation). Mucous is not consistent with anal fissure, swallowed maternal blood or juvenile polyp. Infant would be unwell with bacterial gastroenteritis. Food protein induced proctocolitis would cause blood streaks, mucous and semi formed stools. May be caused by cows milk or soy protein even in breast fed infants.

54

A four-week-old infant presents with persistent diarrhoea. On examination the infant displays swollen upper eyelids and ascites.   His investigations are shown below.

Faecal microscopy:    
  fat globules      +++   
  fatty acid crystals    negative  
  white blood cells    negative  

Full blood count:
  haemoglobin      130 g/L     [90-180]
  white cell count     5.5 x 109/L   [5.0-19.5]
  neutrophils     5.0 x 109/L   [1.0-9.0]
  lymphocytes     0.4 x 109/L   [2.5-9.0]

serum albumin    18 g/L   [29-45]

Which of the following is the most likely diagnosis?

A. Alpha-1-antitrypsin deficiency.
B. Coeliac disease.
C. Cystic fibrosis.
D. Intestinal lymphangiectasia.
E. Nephrotic syndrome.

Answer D. Intestinal lymphangiectasia

Clinical picture of malabsorption (fat globules), with low serum lymphocytes and albumin with oedema and ascites indicates a protein losing enteropathy.

55

A 14-year-old girl presents with jaundice, arthralgia and pruritus over the past week. She has recently returned from a trip to South-East Asia.  
Her liver function and serology results are shown below:

bilirubin      175 µmol/L   [0-15] 
alanine aminotransferase (ALT)  1350 U/L   [<55]
alkaline phosphatase (ALP)   687 U/L   [100-350]
gamma glutamyltransferase (GGT)  425 U/L   [0-40]
total protein      70 U/L   [57-80]
albumin      24 g/L   [33-47]

Epstein-Barr Virus (EBV)-   IgG positive
Epstein-Barr Virus (EBV)-   IgM negative
hepatitis A virus (HAV)-    IgM negative
hepatitis B surface antigen (HBsAg)    negative
anti-hepatitis B core antibody (anti-HBc)  positive
anti-hepatitis C virus antibody (anti-HCV)  negative
antinuclear antibody (ANA)    negative
smooth muscle antibody     positive

What is the most likely diagnosis?
A. Acute hepatitis A.
B. Acute hepatitis B.
C. Autoimmune hepatitis.
D. Epstein-Barr virus hepatitis.
E. Systemic lupus erythematosus. 

Answer C. Autoimmune hepatitis

Liver function tests indicate a hepatic rather than cholestatic insult. EBV IgM is negative and IgG positive indicating past infection with EBV. HAV IgM negative making Hep A unlikely. HBsAg is negative indicating no exposure to Hep B with positive anti-HBc indicating vaccination with Hep B core antibody. ANA negative makes SLE less likely but SMA positive makes an autoimmune condition more likely.

56

An eight-week-old girl presents for investigation of jaundice. She was born at term, and her birth weight was 3800 g. She is breast-fed, thriving and appears generally well and alert. Examination of the heart is normal. Her mother describes the infant’s stools as mustard-coloured to three weeks of age, but becoming very pale over time. The gallbladder is not seen on two fasting abdominal ultrasounds, but normal intrahepatic ducts are seen.
Which of the following is the most likely diagnosis?

A. Alagille syndrome.
B. Alpha-1-antitrypsin deficiency.
C. Biliary atresia.
D. Choledochal cyst.
E. Gallstones.

Answer C. Biliary atresia

Alagille syndrome unlikely as this is known for paucity of intrahepatic bile ducts and is associated with cardiac defects. 

Alpha-1-antitrypsin deficiency can cause neonatal hepatitis and cirrhosis but doesn't affect gallbladder.

Choledochal cyst classic presentation is <10 yrs age with abdo pain, jaundice and palpable mass. Gallbladder would be visible on USS.

Gallstones - would be visible on USS and not likely in this age.

57

A one-year-old boy has infection with Enterobius vermicularis (threadworm/pinworm).  Which of the following is the most appropriate first-line treatment?

A. Co-trimoxazole.
B. Ivermectin. 
C. Metronidazole. 
D. Permethrin.
E. Pyrantel.

Answer E. Pyrantel

Albendazole or mebendazole for older children and adults.

 

58

A toddler is admitted following ingestion of a strong alcoholic drink.  The most common serious complication is:

A.  acute hepatitis.
B.  cerebral oedema.
C.  dehydration.
D.  hypoglycaemia.
E.  pancreatitis.

Answer D. hypoglycemia

Hypoglycemia is caused by inhibition of gluconeogenesis via increased NADH/NAD ratio, decreased release of alanine from muscle, and decreased uptake of gluconeogenic substrate by the liver.

59

An eight-week-old formula-fed baby is referred because he has been crying excessively since four weeks of age.  He pulls up his legs, arches his back and goes red in the face.  He is most distressed in the evenings, but can cry at any time of day. 
He possets after feeds but has not been vomiting, has had no diarrhoea or eczema, and is thriving.

What is the most appropriate first step?

A. Change to a cow’s milk-free formula.
B. Change to a lactose-free formula.
C. Discuss normal infant sleep and cry patterns.
D. Start anti-reflux therapy.
E. Test for urinary tract infection. 

Answer C. Discuss normal infant sleep and cry patterns

Typical picture of normal infant crying.

Reflux may have FTT, significant vomiting (potentially blood streaked) throughout the day and be distressed at any time, not just evening.

No change to stools to indicate cows milk enteropathy and lactose intolerance very unlikely at this age.

In UTI baby would typically be more unwell.

60

Cows milk protein intolerance

These infants are generally healthy but pass blood-tinged stools and mucus; some may be fussy or have increased frequency of bowel movements, but frank diarrhea is not typical. Indeed, the parent usually reports that "aside from the diaper", the child is well. The disorder typically presents between two and eight weeks of age, although there may be a history of bleeding several weeks prior to diagnosis that may have been erroneously attributed to anal fissures. Presentation as early as the first week of life has been described. With complete elimination of the offending protein from the mother's diet or formula, clinical bleeding typically clears within three days.