Kidney and Urinary Tract Disorders Flashcards Preview

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Flashcards in Kidney and Urinary Tract Disorders Deck (127):

GFR at 28 weeks gestation compared to term infant

At 28 weeks the GFR is only 10% of term infant


GFR at term

15-20ml/min per 1.73m2


Changes in GFR post-partum

Rapidly rises to 1-2 years of age when adult rate of 80-120ml/min per 1.73m2 is reached


How are congenital renal abnormalities identified?

Before antenatal US they wouldn't be detected until caused symptoms in infancy/childhood or occasionally adulthood - now detected in utero


What is renal agenesis?

Absence of both kidneys congenitally


What is Potters syndrome?

Oligohydramnios due to decreased urine production due to renal problems (as urine makes up majority of amniotic fluid) leading to fatal condition


Symptoms of Potters syndrome?

Specific facies with low-set ears, beaked nose, prominent epicanthic folds
Pulmonary hypoplasia
Deformed limbs
May be stillborn or die soon after birth due to resp. failure


Plasma Creatinine concentration in children

Main test of renal function
Rises progressively throughout childhood according to height and muscle bulk


eGFR in children

Better measure of renal function than creatinine and useful to monitor renal function serially in children with renal impairment


Inulin or EDTA GFR in children

More accurate as clearance from plasma of substrates freely filtered and not secreted or reabsorbed - but need for repeated blood tests limits use in children


Creatinine clearance in children

Requires timed urine collection and blood tests. Rarely done in children as inconvenient and inaccurate


Plasma urea concentration in children

Same as adults
Increased in renal failure often before creatinine starts rising, raised levels may be symptomatic


What is DMSA scan?

Static scan of renal cortex - detects functional defects such as scars but v.sensitive therefore need to wait 2 months after UTI


What is Micturating cystourethrogram?

MCUG - contrast into bladder through urethral catheter - visualise bladder and urethral anatomy - detects reflux and obstruction


What is MAG3 renogram?

Dynamic isotope scan - measures urinary drainage - best performed with high urine flow
In children >4 (can cooperate) can identify reflux


What is multicystic dysplastic kidney (MCDK)?

Results from failure of union of ureteric bud (ureter/pelvis/calyces/collecting duct) with nephrogenic mesenchyme
Therefore leaves non-functioning structure with multiple large fluid-filled cysts - no renal tissue and no collection to bladder


What happens normally to MCDK?

Half will have involuted by 2 years of age
Nephrectomy only indicated if remains large or hypertension develops (rare)


What is risk with MCDK?

Produce no urine therefore if bilateral will get Potters syndrome


Other causes of large cystic kidneys other than MCDK?

Autosomal recessive and autosomal dominant polycystic kidney disease and tuberous sclerosis


Difference between other cystic kidney disorders and MCDK?

Bilateral BUT some or normal renal function is maintained


Main symptoms of ADPKD in childhood?

Hypertension, haematuria
Renal failure in late adulthood


Extra-renal symptoms with ADPKD? x4

Cysts in liver and pancreas, cerebral aneurysms and mitral valve prolapse


What can abnormal caudal renal migration lead to x2 and possible consequence x2?

Pelvic kidney or horseshoe kidney (lower poles fused in midline) can predispose to infection or obstruction


What does premature division of the ureteric bud lead to?

Duplex system - can be bifid pelvis or complete division with two ureters


Consequence of duplex system x3

Ureters frequently have abnormal drainage so ureter from lower pole moiety often refluxes, whereas upper pole may drain ectopically into urethra or vagina or may prolapse into bladder - therefore obstruction


What is bladder extrophy?

Exposed bladder mucosa as a result of failure of fusion of infraumbilical midline


What is absent musculature syndrome/prune belly syndrome?

Absence or severe deficiency of anterior abdominal wall muscles - frequently associated with a large bladder and dilated ureters and cryptorchidism


Where can obstruction occur in boys?

Posterior urethra due to mucosal folds or a membrane called posterior urethral valves


What can occur in severe obstruction

Dysplastic kidney - small, poorly functioning and may contain cysts and aberrant embryonic tissue
Most severe = Potters syndrome


Antenatal treatment for obstruction

Intrauterine bladder drainage procedures have been attempted but results have been disappointing


Postnatal management of obstruction

Can start prophylactic antibiotics to prevent UTI
If bilateraly hydronephrosis detected in male then ultrasound within 48h to exclude posterior urethral valves
In females or if unilateral hydronephrosis then wait 4-6weeks before US to allow GFR and urine flow to increase because mild outflow obstruction may not be detected with low GFR


Management of posterior urethral valves

Cystoscopic ablation


Why is UTI in childhood important? x2

because up to 1/2 have a structural abnormality in urinary tract
and pyelonephritis may damage growing kidney leaving scars which predispose to hypertension and chronic renal failure if bilateral


UTI presentation in infants

Non-specific, fever normally always present, otherwise generally unwell, lethargy, vomiting, prolonged jaundice and poor feeding etc


UTI presentation in older children

Classical symptoms of loin pain, dysuria, enuresis and frequency become more common with increasing age


Different ways of obtaining a urine sample from a child?

Clean-catch sample when nappy is removed (recommended)
Adhesive plastic bag attached to perineum after careful washing
Catheter - if urgent
Suprapubic aspiration if child unwell


Nitrites in children

Positive result very likely UTI - but some can have nitrite-negative UTI


Leucocyte in children

May be present in UTI but may also be negative
May be present in febrile illness in child without UTI
Positive in balanitis and vulvovaginitis


Normal origin of bacteria causing UTI in children?

Usually from bowel flora unless neonate in which case it is usually haemotogenous


Bacterial cause of UTI in infant?x4

Most common is e.coli (80%)
But can also be proteus, pseudomonas, klebsiela and strep.faecalis


What dose proteus UTI predispose to

Formation of struvite stones - splits urea to ammonia and thus alkalinising the urine


What does pseudomonas UTI indicate

Presence of some structural abnormality hindering drainage


What is vesicoureteric reflux (VUR)?

Developmental abnormality at vesicoureteric junctions - ureters displaced laterally and enter directly rather than at angle therefore with short or absent intramural course


What can severe cases of VUR be associated with?

Renal dysplasia


Inheritance of VUR

familial with 30-50% chance of occurring in 1st degree relative


Variation in severity of VUR?

Can be mild reflux into end of undilated ureter during micturition to severest which is reflux during bladder filling and voiding - distended ureter and clubbed calyces


What can severe VUR lead to?

Intrarenal reflux (IRR) - very high risk of scarring if UTI occurs


What usually happens to VUR?

It usually resolves with age - especially low grade VUR


What is reflux nephropathy?

Small, scarred and shrunken poorly-functioning section of kidney


Management of child with UTI if atypical infection

Atypical = seriously ill, poor urine flow, abdominal/bladder mass, raised creatinine, failure to respond to antibiotics within 48hr, non-e.coli - then USS with DMSA and MCUG


Investigation of UTI

Ultrasound and MCUG (if abnormal USS findings)


Management of infants less than 3 months old with UTI

Hospitalised and IV antibiotics until temperature has settled and then oral antibiotics


Management of acute pyelonephritis/upper UTI in >3 months old (bacteriuria and fever or loin pain/tenderness even if no fever)

Co-amox, cefalexin or cefixime (over 6m)


Management of lower UTI/cystitis in >3 months old

Oral ab's eg. trimethoprin ,cefalexin or amoxicillin for 3 days


Prevention of UTI x7

High fluid intake
Regular voiding
Double micturition
Prevention of constipation
Good perineal hygiene
Lactobacillus acidophilus probiotic to reduce other organisms in gut
Antibiotic prophylaxis if under 2 years old with abnormalities of kidneys or urinary tract, upper UTI or severe reflux (trimethoprim)


What is daytime enuresis?

lack of bladder control during the day in a child old enough to be continent (3-5years)


Causes of daytime enuresis?x7

Lack of attention to bladder sensation
Detrusor instability
Weakness of bladder neck
Neuropathic bladder
Ectopic ureter - constant dribbling


What is neuropathic bladder?

Distended/enlarged bladder - fails to empty properly, irregular thick wall
Associated with spina bifida and other neurological conditions


Investigation of daytime enuresis x5

Neurological exam
Urodynamic studies
X-ray or MRI may show spinal abnormalities
Microscopy, culture and sensitivity


Management of daytime enuresis if no neurological cause

Star charts, bladder training and pelvic floor exercises
If this fails then anticholinergic drugs to reduce bladder contractions eg. oxybutynin


What is secondary enuresis?

Loss of previously achieved urinary continence


Causes of secondary enuresis? x3

Emotional upset (commonest)
Polyuria from osmotic diuresis eg. DM or renal concentrating disorder eg. sickle or chronic renal failure


Investigation of secondary enuresis x3

Urine test for infection, glycosuria and proteinuria
Assessment of urinary concentrating ability by measuring osmolality of an early morning sample
US of renal tract


When can transient proteinuria occur in children?

During febrile illness or after exercise - does not require investigation


Common cause of persistent proteinuria in children? Diagnosis and management

Orthostatic proteinuria - only found when child is upright aka during the day
Diagnosed by measuring urine protein/creatinine ratio in series of early morning urine specimens
Prognosis is excellent no further investigation needed


Clinical signs of nephrotic syndrome x4

Periorbital oedema
Scrotal, vulval, leg and ankle oedema
Breathlessness due to pleural effusions and abdominal distention


What occurs pathologically in nephrotic syndrome?

Heavy proteinuria results in low plasma albumin and oedema


What can be used to treat the majority of nephrotic syndromes in children?

85-90% of children with nephrotic syndrome - proteinuria resolves with corticosteroid therapy and therefore do not progress to renal failure = Steroid-sensitive nephrotic syndrome


Treatment regime in Steroid-sensitive nephrotic syndrome?

Oral steroids daily for 4 weeks and then reducing regime on alternate days until stopping


Response to steroids in SSNS

Usually urine is protein free after 11 days - but now good evidence that extending initial course of steroids can reduce relapse


Features suggesting SSNS x5

Age 1-10 years
No macroscopic haematuria
No hypertension
Normal complement levels
Normal renal function


Serious complications of nephrotic syndrome x4

Hypovolaemia (in extravascular space therefore intravascularly depleted - treat with IV albumin)
Thrombosis (loss of antithrombin in urine, thromocytosis increased with steroids, increased viscosity from raised haemotocrit)
Infection (esp. pneumococcus)
Hypercholesterolaemia (don't know why)


Steroid-resistant nephrotic syndrome management?

Refer to specialist
Diuretics, salt restriction, ACEi and sometimes NSAIDs - for oedema


What is congenital nephrotic syndrome?

Presents in first 3 months of life - recessively inherited (consangueous families)
High mortality due to complications of hypoalbumnaemia rather than renal failure


Management of congenital nephrotic syndrome

May need nephrectomy - followed by dialysis until can have renal transplant


Signs of glomerular haematuria

Brown urine, presence of deformed red cells (as pass through BM), often with proteinuria


Signs of lower UT haematuria

Red colour, at beginning or at end
No proteinuria
Unusual in children


Most common cause of haematuria

UTI (usually not only symptom though)


Pathology of acute nephritis

Increased glomerular cellularity restricts blood flow and therefore decreased filtration


Symptoms of acute nephritis x4

Decreased urine output and volume overload
Hypertension (seizures)
Oedema esp. around eyes
Haematuria and proteinuria


What is post-streptococcal nephritis

Follows streptococcal sore throat or skin infection - common in developing countries but uncommon in developed - prognosis is good


What is Henoch-Schonlein purpura?

Combination of skin rash, arthralgia, oedematous joints (knees and ankles), abdominal pain and glomerulonephritis


When does Henoch-Schonlein purpura occur and in who? x4

Ages 3-10, peak in winter
More common in boys (x2)
Often preceeded by URTI


Presenting feature in Henoch-Schonlein purpura

Rash and fever


Where is rash found in HSP? and what sort

Extensor surfaces of arms and legs
Not on torso
Maculopapular and purpuric


Joint pain in HSP x3 details

Occurs in 2/3rds - especially ankles and knees where there is periarticular oedema - no longterm damage to joints


Abdominal symptoms in HSP

Colicky abdominal pain - treated with steroids
GI petechiae can cause haematemesis and melaena
Intussusception can occur


Renal in HSP

Over 80% have microscopic or macroscopic haematuria or mild proteinuria
Not usually 1st symptom
Make complete recovery normally


If severe proteinuria in HSP

Nephrotic syndrome may result


Presentation of IgA nephropathy

Episodes of macroscopic haematuria
Associated with URTI


What is Alport syndrome? x4

Most common familial nephritis
X-linked recessive
Progresses to end-stage renal failure by early adult life in males
Associated with nerve deafness and ocular defects


Other vasculitis causing haematuria and other symptoms

Wegener disease - prominent involvement of respiratory tract
Also get fever, malaise, weight loss, skin rash and arthropathy
ANCA positive


Treatment of vasculitis causing haematuria eg. Wegeners x3

Steroids, plasma exchange and IV cyclophosphamide


Presentation of HTN in children x6

Vomiting, headache, facial palsy, convulsions, hypertensive retinopathy or proteinuria


Most common features of HTN in infants x2

Failure to thrive and cardiac failure


Causes of unilateral palpable kidneys x5

compensatory hypertrophy
Obstructed hydronephrosis
Renal tumour (Wilms)
Renal vein thrombosis


Causes of bilateral palpable kidneys x4

ADPKD (adults) and ARPKD (children)
Tuberous sclerosis
Renal vein thrombosis


Which polycystic kidney disease presents with enlarged kidneys early in life

Recessive - associated with hypertension, hepatic fibrosis and progresses to chronic renal failure
Dominant is benign in childhood and renal failure onset is in adulthood


Commonest type of renal stones in children and cause?

Struvite stones caused by proteus


Stones which occur with most common metabolic abnormality in children?

Calcium stones occurring in idiopathic hypercalciuria - increased urinary urate and oxalate excretion


Presentation of renal stones in children x4

Haematuria, loin/abdominal pain, UTI or passage of stone


What is Fanconi syndrome?

Generalised proximal tubular dysfunction leading to inadequate reabsorption


What does Fanconi syndrome cause pathologically?

Excessive urinary loss of amino acids, glucose, phosphate, bicarbonate, sodium, calcium, potassium and urate


Presentation of Fanconi syndrome x5

Polydipsia and polyuria
Salt depletion and dehydration
Hyperchloraemic metabolic acidosis
Failure to thrive/poor growth


Commonest type of acute kidney injury in children?



What occurs in renal acute kidney injury

Salt and water retention, blood/protein/casts often in urine
May be symptoms specific to the cause


Management of prerenal causes of AKI

Prerenal AKI is suggested by hypovolaemia therefore correct this - fluid replacement and circulatory support


Management of renal failure AKI

If circulatory overload then fluid restrict and diuretics to increase urinary output
Manage electrolyte imbalances
Treat cause - may need biopsy to identify it


Two commonest causes of renal failure AKI in children in UK

Haemolytic Uraemic Syndrome
Acute Tubular necrosis


Management of post-renal AKI

Relieve obstruction by nephrostomy or bladder catheterisation
Correct obstruction with surgery once fluid and electrolytes have been corrected


What is Haemolytic Uraemic syndrome (HUS)?

Triad of acute renal failure, microangiopathic haemolytic anaemia and thrombocytopenia


What is HUS typically caused by

Secondary to GIT infection with verocytotoxin producing E.coli
Acquired through farm animals or eating uncooked beef


Prodrome for HUS

Bloody diarrhoea


Pathology of HUS

Toxin localises to kidney - causes intravascular thrombogenesis
Coagulation cascade activated, normal clotting (unlike DIC) - platelets consumed - microangiopathic haemolytic anaemia occurs due to damage to RBC as pass through microcirculation which is occluded


What organs other than kidneys can be affected by HUS x3

Pancreas, brain and heart


Management of HUS

Early support and dialysis when prodrome of bloody diarrhoea can give good prognosis
Follow up needed
If no prodrome, may be familial and frequently relapses - high risk of HTN and chronic renal failure


Chronic kidney disease in children

Very rare
10 per million each year


Causes of chronic kidney disease in children

Congenital and familial are more common in childhood than acquired diseases


Clinical features of CKD in children x8

Anorexia and lethargy
Polydipsia and polyuria
Failure to thrive/grow
Bony deformities from renal osteodystrophy
Acute on chronic renal failure precipitated by infection/dehydration
Unexplained normochromic, normocytic anaemia


Aims of management of CKD in children

Prevent symptoms and metabolic abnormalities of CKD to allow normal growth


Management of CKD against anorexia and vomiting

Calorie supplements, may need NGtube or gastrostomy
Protein intake should be sufficient


Pathology of renal osteodystrophy in CKD

Phosphate retention and hypocalcaemia due to decreased activation of vit D leads to secondary hyperparathyroidism - leading to osteitis fibrosa and osteomalacia


Management of renal osteodystrophy in CKD x3

Phosphate restriction (decrease intake of milk products) calcium carbonate as phosphate binder and vit d supplementation


Management of salt and water in CKD

Increased salt and water loss
Therefore salt supplements and water
Bicarbonate supplements to prevent acidosis


Cause and management of anaemia in CKD

Reduced production of erythropoeitin and circulation of toxic metabolites to bone marrow - therefore recombinant human erythropoietin given


Management of hormonal abnormalities in CKD

Recombinant human growth hormone given


Optimal management of CKD

Renal transplant preferably from living related kidneys (higher success rate) and before dialysis is required. But dialysis in the meantime can be given - need to have a minimum weight before transplant can occur to avoid renal vein thrombosis