Nephrology

Question 1

Which stone type is associated with recurrent UTIs?

Answer 1

Struvite.

Struvite stones are formed in the presence of increased urinary ammonia and alkaline urine (>7.2). These occur as a result of urease producing bacteria (and are thus associated with chronic infections).

Question 2

Features of cystinuria?

Answer 2

Cystinuria is an autosomal recessive disorder characterised by the formation of recurrent renal stones. It is due to a defect in the membrane transport of cystine, ornithine, lysine, arginine (mnemonic = COLA).

Recurrent renal stones:
Classically yellow and crystalline, appearing semi-opaque on x-ray

Diagnosis:
cyanide-nitroprusside test

Management:
- Hydration
- D-penicillamine
- Urinary alkalinization

Question 3

Biochemical abnormalities seen in CKD?

Answer 3

1. Low vitamin D (1-alpha hydroxylation normally occurs in the kidneys)
2. High phosphate
3. Low calcium: due to lack of vitamin D, high phosphate
4. Secondary hyperparathyroidism: due to low calcium, high phosphate and low vitamin D

Question 4

Renal biopsy findings for membranous glomerulonephritis?

Answer 4

Membranous glomerulonephritis is the commonest type of glomerulonephritis in adults and is the third most common cause of end-stage renal failure (ESRF). It usually presents with nephrotic syndrome or proteinuria.

Clectron microscopy: the basement membrane is thickened with subepithelial electron dense deposits. This creates a ‘spike and dome’ appearance.

Question 5

Extra renal manifestations of ADPKD?

Answer 5

1. Liver cysts (70% - the commonest extra-renal manifestation): may cause hepatomegaly.
2. Berry aneurysms (8%): rupture can cause subarachnoid haemorrhage
3. Cardiovascular system: mitral valve prolapse, mitral/tricuspid incompetence, aortic root dilation, aortic dissection.
4. Cysts in other organs: pancreas, spleen; very rarely: thyroid, oesophagus, ovary

Question 6

Complications from Nephrotic Syndrome?

Answer 6

1. Increased risk of thromboembolism related to loss of antithrombin III and plasminogen in the urine.
   - Deep vein thrombosis, pulmonary embolism
   - Renal vein thrombosis, resulting in a sudden deterioration in renal function.
   (Patients who have a diagnosis of nephrotic syndrome are in a hypercoagulable state as they are they lose clotting factors in their urine and are often volume depleted due to the high dose diuretics they are placed on).
2. Hyperlipidaemia
   - Increasing risk of acute coronary syndrome, stroke etc.
3. Chronic kidney disease
4. Increased risk of infection due to urinary immunoglobulin loss.
5. Hypocalcaemia (vitamin D and binding protein lost in urine)

Question 7

Spironolactone vs Eplerenone?

Answer 7

Gynaecomastia less common with Eplerenone.