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Kidney Malformations
Multicystic Dysplastic Kidneys
This is a kidney malformation resulting in a non-functioning kidney with large fluid-filled cysts
– The kidney does not contain any renal tissue and there is no connection with the bladder.
– It is due to failed union of the ureteric bud which forms the ureter, pelvis, calyces and collecting ducts and the nephrogenic mesenchyme which forms the kidney tissue
Symptoms:
– The affected kidney is non-functional
– Potter syndrome (severe oligohydramnios and poor foetal development) will result if the lesion is bilateral
Management:
– Half of the affected kidneys with involute by the age of around 2 years
– If the kidney remains large or causes complications (e.g., hypertension), nephrectomy may be needed.
Polycystic kidney disease
This is a genetic condition which leads to the development of multiple cysts on the kidneys.
– It exists as both autosomal dominant and recessive forms:
Autosomal dominant
This is due to a mutation is PKD1 (Chr 16), or PKD2 (Chr 4)
– This is less severe that the autosomal recessive form
Symptoms:
– Clinically silent initially but gives symptoms in early adulthood
– Hypertension (due to renin release), haematuria, cyst infection and kidney failure
– Associated with liver cysts, Berry aneurysms, cardiovascular abnormalities (Mitral valve prolapse, valve incompetence, aortic dissection)
Diagnosis:
– Abdominal ultrasound is used to detect cysts
Management:
– High water intake and kidney transplantation
– Tolvaptan if patients have CKD stage 2/3 or rapidly progressing disease
Autosomal recessive
This is due to mutation in Chromosome 6 (fibrocystin) needed for renal tubule development
Symptoms:
– Presents in infants with renal cysts giving renal failure and hypertension
– Gives associated hepatic fibrosis giving portal hypertension and hepatic cysts
Diagnosis:
Prenatal screening or ultrasound during infancy
Management:
Individuals will probably require kidney transplantation
Horseshoe kidney
This is a condition which occurs when the kidneys are conjoined.
– Rather than being on the two flanks, the single kidney is situated in the lower part of the abdomen near the origin of the inferior mesenteric artery.
Symptoms:
Often asymptomatic, but experience nausea, UTI and stones more frequently
Management:
No treatment for renal fusion, just symptomatic management.
Duplex kidney
This is a developmental condition in which one or both conditions have two ureters which drain urine
– It is the most common renal abnormality occurring in every 1 in 100 people
– It is due to premature division of the ureteric bud, which forms the ureter, pelvis, calyces and collecting ducts
– It can be incomplete (where the two separate ureters join to form a single ureter which enters the bladder) or complete (where two separate ureters from the kidney enter the bladder)
– The duplex ureters lead to problems with the draining or urine so leads to complications of urinary flow
Symptoms:
The ureters often have abnormal drainage causing:
– Urinary Reflux –> this predisposes to urinary tract infections
– Ectopic drainage into urethra/vagina –> this can lead to urinary incontinence
– Ureterocoele
Management:
– If asymptomatic, no treatment is required
– If frequent complications, surgical treatment with ureteroureterostomy maybe required.
Renal Agenesis
This describes the absence of both kidneys and is associated with a high mortality rate.
– Without kidneys, this leads to severe oligohydramnios in utero due to lack of foetal urine production which contributes to the amniotic fluid volume
– This leads to poor development of the fetus (Potter’s syndrome) and is associated with a high mortality
