Kidney and Urinary Tract Disorders Flashcards Preview

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Flashcards in Kidney and Urinary Tract Disorders Deck (127)
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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