CONTENTS



Disorders of fluid and electrolyte and acid base regulation

& hypertension

QUESTIONS

Question: 1

A 16-year-old boy was referred for investigation of renal impairment and hypertension. These had been identified during an assessment for possible diabetes mellitus. He gave a 12 month history of increasing polyuria and polydipsia. He was taking no regular medications. Slit lamp examination findings are shown in the picture (a). His blood pressure was 164/98 mmHg.

Investigations:

serum potassium 3.0 mmol/L (3.5–4.9)

serum bicarbonate 18 mmol/L (20–28)

serum creatinine 110 µmol/L (60–110)

eGFR 80 ml/min

serum phosphate 0.60 mmol/L (0.8–1.4)

serum chloride 112 mmol/L (95–107)

urinalysis trace blood, 2+ protein

1+ glucose

urinary protein:creatinine ratio 56 mg/mmol (90 ml/min

serum magnesium 0.60 mmol/L (0.75–1.05)

serum chloride 83 mmol/L (95–107)

urinary chloride 60

urinary sodium 55

24-hour urinary calcium 1.5 mmol (2.5–7.5)

What is the most likely diagnosis?

A. Bartter’s syndrome

B. Gitelman’s syndrome

C. hypokalaemic periodic paralysis

D. Liddle’s syndrome

E. syndrome of apparent mineralocorticoid excess

NOTES:

Question: 3

A 26 year old woman presented with generalised muscle weakness and recurrent cramps in both arms. On examination her blood pressure was 95/60 mmHg.

Investigations:

serum sodium 136 mmol/L (137–144)

serum potassium 2.0 mmol/L (3.5–4.9)

serum urea 5.3 mmol/L (2.5–7.0)

serum creatinine 86 µmol/L (60–110)

serum magnesium 0.5 mmol/L (0.75–1.05)

serum bicarbonate 34 mmol/L (20–28)

urine chloride 40 mmol/24hrs (100 – 250)

What is the next most appropriate investigation?

A. dexamethasone suppression test

B. genetic testing for CYP11B1/CYP11B2

C. renin-angiotensin ratio

D. salivary sodium

E. urinary calcium

NOTES:

Question: 4

An 18 year old man presented with a 6 month history of worsening tiredness and muscle aches. A male cousin attends nephrology follow-up but it is not clear from the patient why. He was taking no regular medications. On examination his blood pressure was 126/72 mmHg.

Investigations:

serum potassium 3.0 mmol/l (3.5–4.9)

serum bicarbonate 18 mmol/l (20–28)

serum phosphate 0.55 mmol/l (0.8–1.4)

plasma glucose 5.2 mmol/l

serum creatinine kinase 500 U/L (24–195)

urinalysis +protein, +glucose

Which is the most appropriate diagnostic test?

A. CT KUB

B. glucose tolerance test

C. plasma alpha-galactosidase-A level

D. renal biopsy

E. serum bicarbonate after oral loading with sodium hydrogen carbonate

NOTES:

Question: 5

An 18 year old man presented with accelerated hypertension. His father and paternal uncle developed hypertension in their early 20s. After initial intravenous antihypertensive therapy, he was treated with amlodipine 10mg od and ramipril 10mg od. His blood pressure was 142/86 mmHg.

Investigations:

serum potassium 2.7 mmol/L (3.5–4.9)

serum bicarbonate 36 mmol/L (20–28)

plasma renin activity 2.9 pmol/mL/h (3.0–4.3)

plasma aldosterone 950 pmol/L (330–830)

spot urinary potassium 35 mmol/L

Which statement is most correct

A. Cushing’s syndrome is a likely diagnosis.

B. dexamethasone is the treatment of choice.

C. he is a compulsive liquorice eater.

D. he should be screened for 11-β hydroxysteroid deficiency.

E. his blood pressure and hypokalaemia will respond well to inhibiting distal tubular sodium reclamation.

NOTES:

Question: 6

A 42 year old woman was found to have hypertension and was prescribed ramipril. She had a strong family history of hypertension. Six weeks later she developed generalized weakness. Physical examination was unremarkable. Her blood pressure was 136/80 mmHg.

Investigations:

serum sodium 142mmol/L (133-144)

serum potassium 6.4 mmol/L (3.3-5.3)

serum chloride 109 mmol/L (95-105)

serum bicarbonate 19 mmol/L (22-30)

serum creatinine 79 μmol/L (60-120)

plasma renin activity 3.1 pmol/mL/h (3.0–4.3)

plasma aldosterone 250 pmol/L (330–830)

spot urinary sodium 75 mmol/L

spot urinary potassium 20 mmol/L

spot urinary chloride 98 mmol/L

After introduction of bendroflumethiazide the symptoms resolve and serum potassium is 5.2 mmol/L (3.3-5.3).

Which is the most likely diagnosis?

A. Gordon’s syndrome

B. Liddle’s syndrome

C. pseudohypoaldosteronism type 1

D. primary adrenal insufficiency

E. Type IV renal tubular acidosis

NOTES:

Question: 7

A 19 year old man with a family history of hypertension presented with a 3 week history of palpitations. Bendroflumethazide 2.5mg od had been commenced 5 weeks earlier. On examination blood pressure was 170/106 mmHg and he had grade 2 hypertensive retinopathy.

Investigations:

serum sodium 140mmol/L (133-144)

serum potassium 2.2 mmol/L (3.3-5.3)

serum chloride 90 mmol/L (95-105)

serum bicarbonate 34 mmol/L (22-30)

serum creatinine 82 μmol/L (60-120)

plasma renin activity 0.5 pmol/mL/h (3.0–4.3)

plasma aldosterone 750 pmol/L (330–830)

plasma 18-hydroxycortisol markedly above normal

ECG frequent premature ventricular

beats

What is the most appropriate treatment?

A. amiloride

B. dexamethasone

C. dutasteride

D. metyrapone

E. spironolactone

NOTES:

Question: 8

A 65 year old man is admitted with non-specific abdominal pain, nausea, and shortness of breath. He had type II diabetes mellitus and epilepsy. He had been taking linezolid for 6 weeks for an infected knee prosthesis. He was also taking topiramate 100mg bd, metformin 1000mg bd, and rosiglitazone 8mg od. On examination his blood pressure was 136/82, and abdominal examination was unremarkable.

Investigations:

serum sodium 138 mmol/L (133-144)

serum potassium 4.8 mmol/L (3.3-5.3)

serum chloride 101 mmol/L (95-105)

serum creatinine 80 μmol/L (60-120)

plasma glucose 8.2 mmol/L (3.3-6.0)

Arterial blood gas

pH 7.35 (7.35-7.45)

pO2 14.1 kPa (9.3-13.3)

pCO2 3.5 kPa (4.7-6.0)

HCO3 15 mmol/L (22-26)

Base Excess -9.4 (-3 to +3)

What is the most likely cause of the acidaemia?

A. diabetic ketoacidosis

B. linezolid-induced lactic acidosis

C. metformin-induced lactic acidosis

D. ischaemic bowel

E. topiramate-induced type III renal tubular acidosis

NOTES:

Question: 9

A 69-year-old man with refractory IgA lambda multiple myeloma started treatment with lenalidomide 15 mg/day. He was also taking zoledronic acid 4mg IV every 4 weeks. He had stable chronic kidney disease (serum creatinine 150 μmol/L). Three weeks later, he presented with weakness, fatigue, thirst, polyuria, and orthostatic dizziness.

On examination his blood pressure was 110/79 mmHg supine and 83/45 mmHg standing.

Investigations:

serum sodium 147mmol/L (133-144)

serum potassium 2.7 mmol/L (3.3-5.3)

serum chloride 120 mmol/L (95–107)

serum bicarbonate 15 mmol/L (22-30)

serum phosphate 0.25 mmol/L (0.8-1.4)

serum creatinine 239 μmol/L (60-120)

serum urate 59 μmol/L (260-500)

plasma glucose 4.9 mmol/L (3.3-6.0)

arterial blood pH 7.29 (7.35-7.45)

urinalysis pH 7.0

2+ glucose

Urine lambda light chains 5.76 mg/dL

(28.5 mg/dL pre-lenalidomide)

What is the most likely cause of these electrolyte abnormalites?

A. AL amyloidosis

B. bisphosphonate therapy

C. intermediate cystinosis

D. lenalidomide therapy

E. light chain disease

NOTES:

Question: 10

A 68 year old afro-caribbean man presented with a 6 week history of mild confusion and a single complex partial seizure 48 hrs earlier. He had a past medical history of hypertension and diet-treated type II diabetes mellitus. He was usually taking bendroflumethiazide 2.5mg od and atenolol 100mg od, although had taken none for 5 days.

On examination blood pressure 146/92mmHg with no postural drop. He was confused in time, place, and person.

Investigations:

serum sodium 115mmol/L (133-144)

serum potassium 3.8 mmol/L (3.3-5.3)

serum bicarbonate 26 mmol/L (22-30)

serum creatinine 56 μmol/L (60-120)

serum urate 320 μmol/L (260-500)

plasma glucose 25.5 mmol/L (3.3-6.0)

serum cholesterol 4.1 mmol/L (60)

fasting plasma glucose 8.2 mmol/L (3–6)

haemoglobin A1c 9.2 % (3.8–6.4)

serum corrected calcium 2.75 mmol/L (2.2–2.6)

plasma osmolality 282 mosmol/kg (278–300)

urinary osmolality 92 mosmol/kg (350–1000)

abdominal X-ray nephrocalcinosis.

A water deprivation test was performed. After 8 hours the following results were obtained:

urine volume 980 ml

urine osmolality 760 mosmol/kg

plasma osmolality 288 mosmol/kg.

What is the most likely cause of the polyuria?

A central diabetes insipidus

B hypercalcaemia

C hyperglycaemia

D nephrogenic diabetes insipidus

E primary polydipsia

NOTES:

Question: 15

A 65-year-old man with long-standing stage 3 CKD due to diabetic nephropathy developed significant hyperkalaemia. He also had a background of chronic lymphocytic leukaemia and was due to start treatment with low-dose chlorambucil. He was taking gliclazide 80mg bd, furosemide 80mg od, lisinopril 2.5mg od, alfacalcidol 0.25μg od, adcal 2 tablets tds before food He had also been taking calcium resonium 15g bd for 1 week..

On examination, his blood pressure was 138 / 68 mmHg and he was euvolaemic.

Investigations:

serum sodium 135 mmol/L (137–144)

serum potassium 6.8 mmol/L (3.5–4.9)

serum creatinine 205 µmol/L (60–110)

estimated GFR (MDRD) 30 mL/min (>60)

fasting plasma glucose 8.2 mmol/L (3–6)

haemoglobin A1c 9.2 % (3.8–6.4)

haemoglobin 10.5 g/dL (13–18)

white cell count 154( 109/L (4–11)

platelet count 125 ( 109/L (150–400

ECG normal sinus rhythm, normal morphology of QRS-complexes and T-waves

What is the most appropriate next investigation?

A red cell membrane permeability studies

B renin –aldosterone ratio

C serum potassium on a promptly centrifuged sample

D short synacthen test

E simultaneous serum and plasma potassium concentration

NOTES:

APCKD, hereditary nephritis

& less common renal conditions

QUESTIONS

Question: 1

A 19-year-old man was referred for evaluation of renal impairment identified during a recent admission for investigation of palpitations. Examination demonstrated skin changes (Figures a & b) which had become more extensive over the past 2 years. Blood pressure was 145/85 mmHg.

Investigations:

serum creatinine 131 µmol/L (60–110)

eGFR 65 ml/min

protein/creatinine ratio (untimed specimen) 137 mg/mmol (90 ml/min

urinalysis blood 2+

protein/creatinine ratio (untimed specimen) 7 mg/mmol ( ................
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