Chem Path: Paeds clinical chem

Question 1

What are some common problems in low birth weight

Answer 1

Respiratory distress syndrome (RDS)
Retinopathy of prematurity (ROP)
Intraventricular haemorrhage (IVH)
Patent ductus arteriosus (PDA)
Necrotising enterocolitis (NEC)

Question 2

What is NEC

Answer 2

Inflammation of bowel wall leading to necrosis and perforation

bloody stool
Abdo distension 
Pneuomatosis intestinalis (intermural gas)

Question 3

When do nephrons develop in fetus?

Answer 3

Nephrons develop from about week 6 gestation

Question 4

When does the foetus start producing urine?

Answer 4

They start producing urine from week 10

Question 5

When does the Full complement of nephrons start?

Answer 5

36 weeks

Question 6

Is the GFR in babies high and low and why?

Answer 6

LOW as babies have a high surface area

Question 7

Why are babies prone to acidosis?

Answer 7

Low GFR - Low amount of Na available for H+ exchange

Short proximal tubule - Low reabsorbive capacity - Absorption of HCO3 is low

Question 8

Is the threshold for gylcosuria higher or lower than adults in bebes?

Answer 8

Lower

Question 9

Is the maximum urine osmolality higher or lower than adults for kids and why?

Answer 9

Lower

Kids - 700mmol/Kg

Adults - 12500mmol/Kg

Loop of Henle is short

Question 10

Distal tubule is unresponsive to aldosterone - what are the consequences?

Answer 10

Persistant Na loss

Reduced K+ excretion

Question 11

What is the upper normal limit of K+ in adults and kids?

Answer 11

Adults - 5.5

Kids - 6

Question 12

Why do babies lose weight in the first week of life?

Answer 12

They have a lot of ECF as foetuses. After pulmonary resistance goes down post birth, ANP is released and there is redistribution of ECF.

Question 13

What should be measured daily in babies born < 30 weeks?

Answer 13

Na due to increased Na demand coupled with Na loss in kidneys

Question 14

Can you measure Na loss via urine in pre term babies?

Answer 14

NO

Question 15

When can you give K+ supplement to babies?

Answer 15

Only after a urine sample is achieved (>1mL/kg/hour)

Question 16

Why is bicarb given to babies and how does it cause electrolyte disturbances?

Answer 16

For acidosis

There is Na in it and their kidneys cannot excrete it

Question 17

Why is caffeine/theophylline given to babies and how does it cause electrolyte disturbances?

Answer 17

For apnoea

Increases renal Na loss

Question 18

Why is indomethacin given to babies and how does it cause electrolyte disturbances?

Answer 18

For PDA

Causes oliguria

Question 19

When is hyperNa common in kids?

Answer 19

In the first 2 weeks of life

Question 20

What should you consider for hyperNa occurring in kids after 2 weeks of birth?

Answer 20

Salt poisoning

Question 21

What measurements should you do for salt poisoning?

Answer 21

Urea, creatinine and electrolytes on paired urine and plasma

Question 22

What happens in congenital adrenal hyperplasia (CAH)

Answer 22

Lack of aldosterone production leading to salt loss and hypoNa

Question 23

What else happens in CAH?

Answer 23

Hypoglycaemia due to lack of cortisol

Question 24

What happens to sex steroids in CAH and how does it present?

Answer 24

High levels of pregnenolone

Presents in females with ambiguous genitalia

Growth acceleration

Question 25

Why is there hyperbilirubinaemia in neonates?

Answer 25

Increased RBC breakdown as foetal Hb gets destroyed Enhanced enterohepatic circulation - increased reabsorption of bile

Question 26

What can be a complication of hyperbilirubinaemia?

Answer 26

Kernicterus - Bilirubin that crosses the BBB and has neurological defects

Question 27

What are the bilirubin levels for exchange transfusion and phototherapy in term babies and pre term babies and why is it lower for pre term babies?

Answer 27

Exchange transfusion - 450 (term) and 230 (preterm) Phototherapy - 350 (term) and 120 (preterm) Lower for pre term babies as albumin levels are lower and the BBB is leakier

Question 28

What are the other causes of hyperbilirubinaemia?

Answer 28

Haemolytic diseases G6PD deficiency Crigler-Najjar syndrome - Deficiency of bilirubin conjugation

Question 29

What is prolonged jaundice?

Answer 29

>14 days in term babies | >21 days in preterm babies

Question 30

Why can there be prolonged jaundice in babies?

Answer 30

Prenatal infection / sepsis Hypothyroidism Breast milk jaundice

Question 31

Why can you have conjugated hyperbilirubinaemia?

Answer 31

``` Biliary atresia Ascending cholangitis with TPN Galactosaemia Alpha 1 anti trypsin Tyrosinaemia 1 Peroxisomal disorders ```

Question 32

What happens to calcium levels in babies when they are born?

Answer 32

It falls

Question 33

Is calcium or phosphate higher in babies?

Answer 33

Phosphate

Question 34

What happens to babies with hypocalcaemia and low phosphate

Answer 34

Osteopaenia of prematurity

Question 35

What would see on the CXR of a child with Osteopaenia of prematurity?

Answer 35

Fraying Splaying Cupping of long bones

Question 36

If Osteopaenia of prematurity is left untreated, what can you see?

Answer 36

Flailed chest and respiratory difficulties

Question 37

What is the biochem of Osteopaenia of prematurity?

Answer 37

Calcium is the last to change PO4 low ALP > 1200

Question 38

How to treat Osteopaenia of prematurity?

Answer 38

PO4 and calcium given separately OR 1 alpha calcidol

Question 39

How can rickets present?

Answer 39

Bowed legs, frontal bossing, muscular hypotonia May get abdominal laxity Tetany/ hypocalcaemic seizures Hypocalcaemic cardiomyopathy

Question 40

How can transient hypophosphataemia be differentiated from rickets?

Answer 40

Very high ALP | electrophoresis

Question 41

What is pseudo vit D deficiency type 1?

Answer 41

defective renal hydroxylation Treated with 1,25 OH Vit D

Question 42

What is pseudo vit D deficiency type 2?

Answer 42

Defective receptor Treated with 1,25 OH Vit D

Question 43

What is familial hypoPO4 caused by?

Answer 43

Low tubular maximum reabsoprtion of PO4 Raised urine phosphoethanolamine