Question 16#

A 27-year-old man is diagnosed with Goodpasture's syndrome.

Which one of the following does not increase the likelihood of a pulmonary haemorrhage?

A. Smoking

Correct Answer D: Dehydration may decrease the likelihood of a pulmonary haemorrhage. Pulmonary oedema is associated with an increased risk.

Goodpasture's syndrome:
Goodpasture's syndrome is rare condition associated with both pulmonary haemorrhage and rapidly progressive glomerulonephritis. It is caused by anti-glomerular basement membrane (anti-GBM) antibodies against type IV collagen. Goodpasture's syndrome is more common in men (sex ratio 2:1) and has a bimodal age distribution (peaks in 20-30 and 60-70 age bracket). It is associated with HLA DR2.

Features:

• Pulmonary haemorrhage
• Followed by rapidly progressive glomerulonephritis

Factors which increase likelihood of pulmonary haemorrhage:

• Smoking
• Lower respiratory tract infection
• Pulmonary oedema
• Inhalation of hydrocarbons
• Young males

Investigations:

• Renal biopsy: linear IgG deposits along basement membrane
• Raised transfer factor secondary to pulmonary haemorrhages

Management:

• Plasma exchange
• Steroids
• Cyclophosphamide

Question 17#

A 72-year-old woman who has been on the ward for the past five days is noted by the nurses not to be passing much urine. She was admitted originally with pneumonia but has since developed diarrhoea. Blood tests show her creatinine has increased from 98 to 172 μmol/l.

Which one of the following tests is most useful when determining whether there is prerenal uraemia or acute tubular necrosis?

A. Serum urea level

Correct Answer E: In Prerenal uraemia - kidneys hold on to sodium to preserve volume.

Acute renal failure:

Acute tubular necrosis vs. Prerenal uraemia:

*Fractional sodium excretion = (urine sodium/plasma sodium) / (urine creatinine/plasma creatinine) x 100

**Fractional urea excretion = (urine urea /blood urea ) / (urine creatinine/plasma creatinine) x 100

Question 18#

Which one of the following statements regarding the assessment of proteinuria in patients with chronic kidney disease is incorrect?

A. Albumin:creatinine ratio (ACR) is more sensitive than protein:creatinine ratio (PCR)

Correct Answer C: Proteinuria is an important marker of chronic kidney disease, especially for diabetic nephropathy. NICE recommend using the albumin:creatinine ratio (ACR) in preference to the protein:creatinine ratio (PCR) when identifying patients with proteinuria as it has greater sensitivity. For quantification and monitoring of proteinuria, PCR can be used as an alternative, although ACR is recommended in diabetics. Urine reagent strips are not recommended unless they express the result as an ACR.

Approximate equivalent values:

Collecting an ACR sample:

• By collecting a 'spot' sample it avoids the need to collect urine over a 24 hour period in order to detect or quantify proteinuria
• Should be a first-pass morning urine specimen
• If the initial ACR is greater than 30 mg/mmol and less than 70 mg/mmol, confirm by a subsequent early morning sample. If the initial ACR is greater than 70 mg/mmol a repeat sample need not be tested Interpreting the ACR results
• In non-diabetics an ACR greater than 30 mg/mmol is considered clinically significant proteinuria
• In diabetics microalbuminuria (ACR greater than 2.5 mg/mmol in men and ACR greater than 3.5 mg/mmol in women) is considered clinically significant

Question 19#

Which one of the following is least recognized as a cause of membranous glomerulonephritis?

A. Malaria

Correct Answer D: 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.

Renal biopsy demonstrates:

• Sub-epithelial immune complex (mainly IgG and C3) deposition in the glomerulus
• Electron microscopy: the basement membrane is thickened with sub-epithelial electron dense deposits

Causes:

• Idiopathic
• Infections: hepatitis B, malaria
• Malignancy: lung cancer, lymphoma, leukaemia
• Drugs: gold, penicillamine, NSAIDs
• Systemic lupus erythematosus (class V disease)

Prognosis - rule of thirds:

• One-third: spontaneous remission
• One-third: remain proteinuric
• One-third: develop ESRF

Management:

• Immunosuppression: corticosteroids alone have not been shown to be effective. A combination of corticosteroid + another agent such as chlorambucil is often used
• Blood pressure control: ACE inhibitors have been shown to reduce proteinuria
• Consider anticoagulation

Question 20#

Autosomal dominant polycystic kidney disease type 1 is associated with a gene defect in:

A. Chromosome 4

Correct Answer D: Autosomal dominant polycystic kidney disease (ADPKD) type 1 = chromosome 16 = 85% of cases.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of kidney disease, affecting 1 in 1,000 Caucasians. Two disease loci have been identified, PKD1 and PKD2, which code for polycystin-1 and polycystin-2 respectively.

The screening investigation for relatives is abdominal ultrasound:

Ultrasound diagnostic criteria (in patients with positive family history)

• Two cysts, unilateral or bilateral, if aged < 30 years
• Two cysts in both kidneys if aged 30-59 years
• Four cysts in both kidneys if aged > 60 years