Nephrology

Question 1

Most common organism associated with peritonitis in peritoneal dialysis?

Answer 1

Staphylococcus epidermidis.

Coagulase-negative staphylococci such as Staphylococcus epidermidis are the most common cause of peritonitis in peritoneal dialysis (PD) patients. In the case of Staphylococcus epidermidis, this is often caused by intra-abdominal translocation of this normal skin commensal organism via the dialysis line.

Question 2

Examples of extra-renal manifestations of ADPKD?

Answer 2

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 (25%),
   mitral/tricuspid incompetence, aortic root dilation, aortic dissection.
4. Cysts in other organs: pancreas, spleen; very rarely: thyroid, oesophagus, ovary.

Question 3

Indications for RRT?

Answer 3

A - Metabolic Acidosis (pH <7.1)

E - Electrolytes Refractory Hyperkalemia

I - Intoxication

O - Overload volume overload refractory to diuresis

U - Uremia elevated urea with signs or symptoms of uremia (pericarditis, neuropathy, or uremic encephalopathy)

Question 4

Investigation of choice for patients with suspected ADPKD?

Answer 4

The screening investigation for relatives is abdominal ultrasound:

Ultrasound diagnostic criteria (in patients with positive family history):

2 cysts, unilateral or bilateral, if aged < 30 years.

2 cysts in both kidneys if aged 30-59 years.

4 cysts in both kidneys if aged > 60 years.

Question 5

Features of HSP?

Answer 5

Henoch-Schonlein purpura (HSP) is an IgA mediated small vessel vasculitis. HSP is usually seen in children following an infection.

Features:

• Palpable purpuric rash (with localized oedema) over buttocks and extensor surfaces of arms and legs
• Abdominal pain
• Polyarthritis
• Features of IgA nephropathy may occur e.g. haematuria, renal failure

Question 6

Features of acute intersitital nephritis?

Answer 6

Features:
- Fever, rash, arthralgia
- Eosinophilia
- Mild renal impairment
- Hypertension

Investigations:
- Sterile pyuria
- White cell casts

Question 7

Causes of Acute interstitial nephritis?

Answer 7

Causes:

1. Drugs: the most common cause, particularly antibiotics:
   - Penicillin
   - Rifampicin
   - NSAIDs
   - Allopurinol
   - Furosemide

• Systemic disease: SLE, sarcoidosis, and Sjögren’s syndrome
• Infection: Hanta virus , staphylococci

Question 8

Tumour marker for testicular seminomas?

Answer 8

hCG.

hCG is associated with testicular seminomas

Semen causes pregnancy –> seminomas caused raised beta hCG

Question 9

Which medication causes nephrogenic DI?

Answer 9

Diabetes insipidus in patients taking lithium mechanism: lithium desensitizes the kidney’s ability to respond to ADH in the Collecting Ducts.

Question 10

Autosomal dominant polycystic kidney disease type 2 is associated with a gene defect in which Chromosome?

Answer 10

Chromosome 4. ADPKD type 2 is associated with mutations in the PKD2 gene, which is located on chromosome 4.

This gene codes for a protein called polycystin-2, which appears to be involved in regulating cell division and preventing the formation of cysts. Mutations in this gene can disrupt these functions and lead to the development of ADPKD.

Question 11

Autosomal dominant polycystic kidney disease type 1 is associated with a gene defect in which Chromosome?

Answer 11

Chromosome 16.

Question 12

First line pharmacological option for BPH?

Answer 12

Alpha-1 antagonists e.g. Tamsulosin, Alfuzosin. Decrease smooth muscle tone of the prostate and bladder

Question 13

Main composition of stag-horn calculus ?

Answer 13

Struvite (ammonium magnesium phosphate).

Struvite stones are typically associated with urinary tract infections caused by urease-producing organisms, such as Proteus, which is identified in the urine culture.

Urease breaks down urea into ammonia and carbon dioxide, leading to an alkaline urine pH that promotes struvite crystal formation.

Staghorn calculi are often composed of struvite and can occupy a large portion of the renal pelvis.

Question 14

Pharmacological management of ADPKD?

Answer 14

For select patients, Tolvaptan (vasopressin receptor 2 antagonist) may be an option.

NICE recommended it as an option for treating ADPKD in adults to slow the progression of cyst development and renal insufficiency

Question 15

Which autoantibody is associated with membranous glomerulonephritis?

Answer 15

Anti-phospholipase A2 antibodies.

Membranous glomerulonephritis is the commonest type of glomerulonephritis in adults and is the third most common cause of ESRF. It usually presents with nephrotic syndrome or proteinuria.

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

Causes
- idiopathic: due to anti-phospholipase A2 antibodies
- infections: hepatitis B, malaria, - syphilis
- malignancy (in 5-20%): prostate, lung, lymphoma, leukaemia
- drugs: gold, penicillamine, NSAIDs
- autoimmune diseases: systemic lupus erythematosus (class V disease), thyroiditis, rheumatoid

Question 16

Mode of inheration for Alport’s syndrome?

Answer 16

Alport’s syndrome - X-linked dominant (in the majority).

It is due to a defect in the gene which codes for Type IV collagen resulting in an abnormal glomerular-basement membrane (GBM). The disease is more severe in males with females rarely developing renal failure.

Alport’s syndrome usually presents in childhood. Features:
- Microscopic haematuria
- Progressive renal failure
- Bilateral sensorineural deafness
- Lenticonus: protrusion of the lens surface into the anterior chamber
- Retinitis pigmentosa
- Renal biopsy: splitting of lamina densa seen on electron microscopy

Renal biopsy
electron microscopy: characteristic finding is of the longitudinal splitting of the lamina densa of the glomerular basement membrane, resulting in a ‘basket-weave’ appearance.

Question 17

Mechanism of tolvaptan?

Answer 17

Tolvaptan is a vasopressin receptor 2 antagonist.

Tolvaptan which is licensed for the treatment of autosomal dominant polycystic kidney disease.

Question 18

Patients with nephrotic syndrome develop a hypercoagulable state due to loss of what?

Answer 18

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

Question 19

In patients with hypercalciuria and renal stones, which medication can help decrease stone formation?

Answer 19

Bendroflumethiazide - a thiazide diuretic.

The use of such a drug reduces calcium excretion, thereby reducing calcium stone formation.