Clinical SBAs
Clinical Renal: (19 questions)

Questions

• 1
  A 12-year old boy presents with facial puffiness. Urinalysis shows gross proteinuria and no haematuria. Plasma albumin = 21 g/L. He was previously fit and well. What is the most likely biopsy finding?
  Difficulty: Hard     Topic: Proteinuria in 12-year old
  a

  Diffusely thickened GBM with IgG & C3 deposits

  b

  Some glomeruli are partly scarred, with IgM & C3 deposition

  c

  Normal glomeruli on light microscopy; podocyte foot process fusion seen on EM

  d

  A thinned GBM seen on EM

  e

  Mesangial proliferation with C3 and IgA deposits
  Explanation: The most common cause of nephrotic syndrome in children is minimal change disease. It appears normal on light microscopy but there is loss of foot process interdigitation, with fusion on electron microscopy. It responds well to steroids therefore nephrotic syndrome in children is first given a steroid trial before biopsy. Post-streptococcal GN causes a thickened GBM with IgG & C3 deposits. Focal segmental glomerulosclerosis gives the appearance of scarred glomeruli with IgM deposited. Thin GBM disease has such an appearance on histology and it causes haematuria. IgA nephropathy shows mesangial proliferation in response to IgA deposits.
• 2
  A 15-year old boy presents with a purpuric rash on both legs, abdominal pain and haematuria. What is the most likely diagnosis?
  Difficulty: Easy     Topic: Purpuric rash and haematuria
  a

  Kawasaki disease

  b

  Henoch-Schonlein syndrome

  c

  Polyarteritis nodosa

  d

  Berger's disease

  e

  Churg-Strauss syndrome
  Explanation: Henoch-Schonlein syndrome is a small vessel vasculitis that usually presents in teenage boys with characteristic palpable purpura on the extensor surface of both legs that spares the trunk and face. It affects the bowel, causing bloody diarrhoea and pain; as well as haematuria. Kawasaki disease causes fever in children and is associated with coronary artery aneurysm. Berger's disease (IgA nephropathy) does not cause purpura, only painless haematuria. Churg-Strauss syndrome presents with asthma, eosinophilia and neuropathy.
• 3
  A 19-year old man presents with haematuria. He has been well apart from a skin infection 2 weeks ago. Blood pressure is 162/102mmHg. There are red cell casts in the urine and, C3 is low and ANCA is negative. What is the most likely diagnosis?
  Difficulty: Medium     Topic: Haematuria post-infection
  a

  Post-streptococcal glomerulonephritis

  b

  Malignant hypertension

  c

  IgA nephropathy

  d

  Microscopic polyangiitis

  e

  Alport’s syndrome
  Explanation: Post-streptococcal GN is most common in young men after a skin or throat infection with group A beta-haemolytic streptococci. It presents as nephritic syndrome 10-25 days post-infection, in contrast with IgA nephropathy that presents within days of infection. Negative ANCA helps to exclude vasculitic causes of nephritic syndrome that may cause rapidly-progressive glomerulonephritis e.g. microscopic polyangiitis. Malignant HTN does not cause low C3 and IgG but does cause red-cell casts. Alport's syndrome presents with haematuria but without hypertension and low C3, or with chronic renal failure.
• 4
  A 20-year old medical student presents with intermittent frank haematuria that occur a few days after a sore throat. What is the most likely diagnosis?
  Difficulty: Medium     Topic: Intermittent frank haematuria
  a

  Alport's syndrome

  b

  Thin glomerular basement membrane (GBM) disease

  c

  Rapidly progressive glomerulonephritis

  d

  Bueger's disease

  e

  IgA nephropathy
  Explanation: IgA nephropathy (or Berger's disease) causes intermittent haematuria (which may be microscopic) with 5 days of infection. IgA deposits with C3 in the mesangium, causing proliferation. Alport's syndrome and thin GBM disease are less common and present with haematuria and aren't associated with infection. RPGN causes impairment of renal function, hypertension and proteinuria. Bueger's disease (thromboangiitis obliterans) is arterial and venous thromboses in smokers who are often young and male.
• 5
  A 23-year old woman is admitted for administration of IV flucloxacillin to treat cellulitis. She develops a mild fever and rash. Urea = 11mmol/L and there are eosinophils present in the urine. What is the most likely diagnosis?
  Difficulty: Easy     Topic: Eosinophiliuria
  a

  Pre-renal failure

  b

  Anaphylaxis

  c

  Interstitial nephritis

  d

  IgA nephropathy

  e

  Churg-Strauss syndrome
  Explanation: Interstitial nephritis is inflammation of the renal tissue between tubular cells, acutely it occurs due to an immune reaction most commonly from penicillin-based antibiotics or NSAIDs. Fever, rash and eosinophilia are key features - none of these would be present in pre-renal failure or IgA nephropathy. Anaphylaxis would cause cardiovascular or airway compromise rather than renal failure. Churg-Strauss syndrome is unlikely to present as acute and is accompanied with asthma.
• 6
  A 25-year old man presents with acute renal failure 3 days after gastroenteritis with bloody diarrhoea. He is thrombocytopenic and anaemic with fragmented red cells on the peripheral film. What is the most likely diagnosis?
  Difficulty: Medium     Topic: ARF after gastroenteritis
  a

  Falciparum malaria

  b

  Haemolytic uraemic syndrome (HUS)

  c

  Thrombotic thrombocytopenic purpura (TTP)

  d

  Typhoid fever

  e

  Shigella septicaemia
  Explanation: HUS occurs due to endothelial cell damage that results in thrombus formation in renal vessels, which causes microangiopathic haemolytic anaemia. This causes: haemolysis, thrombocytopenia and ARF. The most common precipitant is enterohaemorrhagic E. coli. TTP results in more severe haemolysis and CNS signs, including seizures; it is not associated with infection. Malaria would show ring-inclusions in RBC and a travel history. Typhoid and Shigella don't feature haemolysis.
• 7
  A 40-year old man presents with acute renal failure. Biopsy shows crescentic glomerulonephritis. He also reports recurrent epistaxis and there is collapse of the nasal bridge. What is the most likely diagnosis?
  Difficulty: Easy     Topic: Crescentic glomerulonephritis
  a

  Microscopic polyangiitis (MPA)

  b

  Goodpasture's syndrome

  c

  Behcet's syndrome

  d

  Polyarteritis nodosa (PAN)

  e

  Wegener's granulomatosis (WG)
  Explanation: The most common causes of crescentic glomerulonephritis (RPGN) are ACNA+ vasculitidies: microscopic polyangiitis and Wegener's granulomatosis; both of which can cause a nephro-pulmonary syndrome. WG is favoured here due to the history of upper respiratory damage; also WG is cANCA+ and neuropathy is more common, whereas MPA is pANCA+. Goodpasture's causes massive pulmonary haemorrhage and does not involve upper respiratory tract. Behcet's causes ulceration and ocular symptoms. PAN does not cause RPGN.
• 8
  A 40-year old man presents with severe colicky pain in his left flank, which radiates to the groin. What is the most appropriate analgesia?
  Difficulty: Hard     Topic: Renal colic analgesia
  a

  Paracetamol

  b

  Aspirin

  c

  Indomethacin

  d

  Tramadol

  e

  Morphine
  Explanation: This man has renal colic, which is almost always caused by contraction of the ureter against a stone. The most common form of stone is calcium oxalate, others include magnesium sulphate and urate. Best analgesia comes from strong a NSAID, therefore indomethacin is first line from the above list. It is often associated with vomiting therefore the analgesia may need to be given PR. Opiates increase nausea, pethidine should be especially avoided.
• 9
  A 41-year old man with type 1 diabetes has an eGFR of 29ml/min. Toxicity of which drug would manifest with coarse tremor and vomiting?
  Difficulty: Medium     Topic: Drugs in renal failure
  a

  Digoxin

  b

  Gentamicin

  c

  Lithium

  d

  Paracetamol

  e

  Tetracycline
  Explanation: Many drugs are excreted renally, including all of those listed except paracetamol. Lithium levels may become dangerously high in CKD manifesting toxicity with coarse tremor, confusion and vomiting; it also causes nephrogenic diabetes insipidus. Digoxin may reach toxic levels in CKD, worsened by diuretic-induced hypokalaemia. Gentamicin is nephrotoxic, even more so in CKD. Paracetamol can cause acute tubular necrosis in overdose but it does not require adjustment to normal doses. Tetracycline can cause tubulo-interstitial nephritis or nephrotoxicity and patients with CKD are at greater risk.
• 10
  A 45-year old woman presents with facial puffiness. She is proteinuric with a serum albumin of 19g/L. She is treated with gold for rheumatoid arthritis. What is the most likely diagnosis?
  Difficulty: Easy     Topic: Proteinuria with RA
  a

  Thin glomerular basement membrane (GBM) disease

  b

  Focal segmental glomerulosclerosis (FSGS)

  c

  Minimal change disease

  d

  Membranous nephropathy

  e

  Rapidly progressive glomerulonephritis
  Explanation: The most common cause of nephrotic syndrome in adults in membranous nephropathy, which can also be caused by gold, RA, hepatitis B and malignancy. Thin GBM disease causes intermittent haematuria with good long-term prognosis. FSGS is associated with HIV, heroin and sickle cell; it causes nephrotic syndrome but membranous glomerulonephritis is more a common cause of nephrotic syndrome. Minimal change disease is the most common cause of nephrotic syndrome in children but is infrequent in adults. RPGN causes renal failure and a nephritic syndrome.
• 11
  A 47-year man old presents acutely with a left-leg DVT, proteinuria, anasarca and raised JVP. Which pair of findings would best support the diagnosis?
  Difficulty: Medium     Topic: Anasarca and DVT
  a

  Rheumatoid factor positive & Anti-CCP positive

  b

  Ejection fraction <30% & a pan-systolic murmur

  c

  Raised PTH activity & hypocalcaemia

  d

  Hyperkalaemia & creatinine 450mmol/L

  e

  Hypoabluminaemia + hypercholesterolaemia
  Explanation: This man has nephrotic syndrome: oedema, hypoalbuminaemia and proteinuria. Other features are hypercholesterolaemia and increased risk of VTE. Positive rheumatoid factor and anti-CCP would suggest rheumatoid arthritis, which can cause membranous nephropathy or rarely RPGN. A reduced ejection fraction suggests cardiac failure and a pan-systolic murmur due to mitral/tricuspid regurgitation or a VSD. Low calcium with raised PTH occurs in chronic renal failure with secondary hyperparathyroidism, which would not acute in acute nephrotic syndrome. Raised potassium and creatinine occurs in acute renal failure, which is not commonly associated with nephrotic syndrome.
• 12
  A 53-year old man with acute renal failure. His potassium is 6.3mmol/L, his ECG shows a sine-wave pattern after being given 10mmol calcium gluconate, an insulin-dextrose infusion and a salbutamol nebuliser. What is the next step in his management?
  Difficulty: Medium     Topic: Dialysis indications
  a

  Calcium gluconate 10mmol

  b

  Calcium resonium

  c

  Haemodialysis

  d

  Peritoneal dialysis

  e

  Sodium bicarbonate IV
  Explanation: The indications for acute dialysis are: hyperkalaemia with early ECG changes or which is refractory to medical therapy, refractory pulmonary oedema, severe metabolic acidosis, uraemic pericarditis/encephalopathy, small molecule poisoning. This man has refractory hyperkalaemia with late ECG changes. He has already been given optimum medical management: calcium gluconate to stabilise the myocardium (this will not lower serum potassium), then an insulin-dextrose infusion. If there is no response a nebulised beta-2-agonist (salbutamol) can be given. Haemodialysis is required to correct the hyperkalaemia and prevent fatal ventricular arrhythmias. Further calcium gluconate may be tried but 10mmol has already been given. Calcium resonium bind potassium in the bowel so takes days to work. Peritoneal dialysis is not used in emergencies. Sodium bicarbonate may be tried for refractory acidosis but we are not told about this patients acid-base status.
• 13
  A 55-year old man presents with weight loss, mononeuritis multiplex and abdominal pain. He also suffers from angina. Livedo reticularis is present. Urea = 12mmol/L. What further finding would support the most likely diagnosis?
  Difficulty: Hard     Topic: Weight loss and mononeuritis multiplex
  a

  Multiple microaneurysms on renal angiography

  b

  High pANCA titre

  c

  High cANCA titre

  d

  Anti-GBM antibodies

  e

  Immune complexes that precipitate in the cold
  Explanation: This man has polyarteritis nodosa, which most presents at 40-60yrs and is twice as common in men. Cardiac involvement with ischaemia and arrhythmia is the 2nd most common cause of death. Renal microaneurysms on angiogram is characteristic of PAN, causing infarcts. Microscopic polyangiitis is pANCA positive and Wegener's granulomatosis is cANCA positive. Cryoglobulinaemia is characterised by immune complexes that precipitate in the cold. None of these conditions commonly affect the coronary vessels. Anti-GBM antibodies are pathogenic in Goodpasture's syndrome, that is specific for a nephro-pulmonary syndrome.
• 14
  A 57-year old woman with poorly controlled rheumatoid arthritis presents with renal colic and haematuria. IVU demonstrates bilaterally clubbed calyces with spurs and hooks. What is the most likely diagnosis?
  Difficulty: Medium     Topic: Renal manifestations of RA
  a

  Amyloid kidney

  b

  IgA nephropathy

  c

  Interstitial nephritis

  d

  Membranous nephropathy

  e

  Papillary necrosis
  Explanation: Papillary necrosis may be part of analgesic nephropathy from prolonged NSAID use, which most RA patients will require to for analgesia, especially if poorly controlled. Papillary necrosis can present with colic (from shed papillas in the ureters), haemturia or chronic renal failure. IVU shows damaged papillae with unaffected cortex. Interstitial nephritis also occurs from NSAID use; there is an inflammatory reaction with eosinophils in the urine and reduced renal function. Membranous nephropathy can be a direct effect of RA, from gold or penicillamine but presents with nephrotic syndrome. AA amyloidosis is a common, but usually asymptomatic long-term complication of RA. Amyloidosis infiltrates the renal parenchyma and causes large kidney. IgA nephropathy is not associated with RA, it is an idiopathic condition of immune complex deposition in the glomeruli that results in haematuria.
• 15
  A 62-year old lady presents with temporal headaches. ESR = 55mm/hr. What is the most likely diagnosis?
  Difficulty: Easy     Topic: Temporal headaches
  a

  Polymyalgia rheumatica (PMR)

  b

  Giant cell arteritis (GCA)

  c

  Polyarteritis nodosa (PAN)

  d

  Takayasu arteritis

  e

  Rheumatoid arthritis (RA)
  Explanation: GCA is a large vessel vasculitis where 25% of patients have a history of PMR. Diagnostic criteria needs 3 of: >50yrs, new localised headache, temporal artery tenderness, ESR >50mm/hr, abnormal biopsy. Biopsy is not always diagnostic because there can be 'skip lesions' in the artery, areas where the vessel is not affected. Therefore a negative temporal artery biopsy does not exclude GCA and high-dose steroids should be used anyway. The higher ESR and headache favour GCA rather than polymyalgia rheumatica. PAN presents with neuropathy, weight loss and renal infarcts. Takayasu arteritis affects young people with limb ischaemia. RA vasculitis affects pericardium, pleura, the eye and the most common manifestation of RA vasculitis is development of subcutaneous nodules.
• 16
  A 72-year old man with chronic kidney disease presents with breathlessness after a 2-day history of diarrhoea and vomiting. Examination of the chest is normal. Blood gases show: pH 7.30, PaO2 12.2 kPa, PaCO2 3.0 kPa, anion gap = normal. What is the most likely cause of his breathlessness?
  Difficulty: Medium     Topic: Shortness of breath in CKD
  a

  Pulmonary oedema

  b

  Acute-on-chronic kidney injury

  c

  Lactic acidosis

  d

  Myocardial infarction

  e

  Pneumonia
  Explanation: Patients with CKD are more likely to develop acute renal failure. In this case, gastroenteritis has caused pre-renal failure with a metabolic acidosis: the pH is low, with a low CO2 and normal anion gap. Vomiting alone usually causes a metabolic alkalosis but severe dehydration will have also resulted in metabolic acidosis from renal failure. The pH demonstrates that the net effect is an acidaemia, which is responsible for stimulating the respiratory centre and causing breathlessness. Pulmonary oedema would give fine inspiratory crackles in the chest. Lactic acidosis causes a raised anion gap and most commonly occurs to patients who a septic, in liver failure or being treated with metformin. Myocardial infarction tends to cause acidosis through hypoperfusion, resulting in raised lactate. Pneumonia would also give findings on examination.
• 17
  A 78-year old man has chronic renal failure due to diabetes. eGFR = 11ml/min. Which of the following is least likely to be part of his management?
  Difficulty: Easy     Topic: Diabetic kidney disease
  a

  Bisphosphonates

  b

  Metolazone

  c

  Haemofiltration

  d

  Gabapentin

  e

  Lisinopril
  Explanation: Haemofiltration is a form of renal replacement therapy used in high-dependency units when patients are not haemodynamically stable enough for haemodialysis. However the rate of exchange for haemofiltration is much lower than that for haemodialysis therefore less fluid and electrolytes can be removed in the same time. This makes haemodialysis more appropriate for intermittent sessions in patients with stable chronic renal failure. It is not appropriate for treatment of chronic renal failure. Bisphosphonates treat osteodystrophy to reduce fracture rate. Metolazone is a potent thiazide diuretic used when patients are refractory to furosemide. Gabapentin can help treat restless legs or painful neuropathy. Lisinopril is vital to reduce the rate of decline, especially in proteinuric patients.
• 18
  Which of the following a sign of increased intravascular volume?
  Difficulty: Easy     Topic: Volume status
  a

  JVP at 4cm when at 90 degrees

  b

  Capillary refill >3s

  c

  JVP just visible when at 30 degrees

  d

  No change in systolic blood pressure on standing

  e

  Bilateral pitting peripheral oedema
  Explanation: The jugular venous pulse is normally just visible above the thoracic inlet at 45 degrees. It is >4cm high above the angle of Louis (sterno-manubrial joint) at 45 degrees then central venous pressure is raised. At 90 degrees a JVP visible above the thoracic inlet is equivalent to a >4cm raised JVP when at 45 degrees - therefore suggests raised intravascular volume. If only just visible when at 30 degrees, this suggests under-filling. Capillary refill of >3s is a sign of poor peripheral perfusion however may also occur with cold peripheries therefore must be interpreted in context of the environment. Normally there is no change or only a very small decline in systolic BP on standing. Oedema reflects interstitial, not intravascular volume, for example a patient may be oedema with reduced intravascular volume.
• 19
  Which of the following best indicates that renal failure is acute, not chronic?
  Difficulty: Easy     Topic: Acute renal failure features
  a

  Anaemia

  b

  Osteoporosis

  c

  Hyperkalaemia

  d

  Hypophosphataemia

  e

  Hypocalcaemia
  Explanation: All of the above can occur in chronic renal failure but hyperkalaemia more commonly occurs in acute renal failure than chronic. Chronic kidney disease can cause a persistent hyperkalaemia but this is less common than in acute kidney injury. Anaemia occurs due to reduction in EPO production from renal tubular cells. EPO replacement injections is the best treatment however it is not universally available. Osteoporosis occurs as part of renal osteodystrophy: vitamin D deficiency and secondary hyperparathyroidism, which causes low phosphate. The stimulus for hyperparathyroidism is hypocalcaemia, which the chronically failing kidney is unable to reabsorb.