Endgames Case review

Spontaneous hypokalaemia in a man with treated hypertension

BMJ 2015; 350 doi: http://dx.doi.org/10.1136/bmj.h2154 (Published 30 April 2015) Cite this as: BMJ 2015;350:h2154
  1. S H Ahmed, consultant physician, diabetes and endocrinology1,
  2. David L Ewins, consultant physician, diabetes and endocrinology1,
  3. Sunil Nair, consultant physician, diabetes and endocrinology1,
  4. Franklin Joseph, consultant physician, diabetes and endocrinology1
  1. 1Department of Diabetes and Endocrinology, Countess of Chester Hospital, Chester CH2 1UL, UK
  1. Correspondence to: Dr S H Ahmed drharis_76{at}yahoo.co.uk

An 80 year old man with a history of hypertension, stage 3 chronic kidney disease, and paroxysmal atrial fibrillation presented feeling generally unwell and lethargic. He was taking amiodarone 200 mg, bisoprolol 10 mg, amlodipine 10 mg, and lisinopril 20 mg a day. He did not have a fever and he was haemodynamically stable. His blood pressure was controlled (132/84 mm Hg). Physical examination was unremarkable. Blood tests showed hypokalaemia (1.9 mmol/L, reference range 3.5-5.0), hypomagnesaemia (0.58 mmol/L, 0.6-1.2), and metabolic alkalosis (35 mmol/L, 20-32). His symptoms resolved after electrolyte replacement and he was discharged home.

When later reviewed in clinic, a focused history was taken and tests were organised to evaluate the causes of hypokalaemia and hypertension. He had no family history to explain this presentation, or a history of excess use of liquorice, carbenoxolone, or grapefruit juice. Cortisol after overnight dexamethasone (1 mg taken at midnight) suppression was 38 mmol/L (normal response <50). Renin and aldosterone were measured after substituting bisoprolol, lisinopril, and amlodipine with doxazosin. The results showed renin 0.2 ng/mL/h (reference ranges: supine 0.2-2.8, upright 1.8-5.1), aldosterone 977 pmol/L (supine 80-300, upright 140-800); calculated aldosterone:renin ratio 4885 (<590). Given the biochemical abnormality, he underwent computed tomography of the abdomen (figs 1 and 2).

Fig 1 Coronal computed tomogram of the abdomen

Fig 2 Cross sectional computed tomogram of the abdomen

Questions

  • 1. What abnormality does the computed tomogram show?

  • 2. What is the probable diagnosis?

  • 3. What further investigations are needed to confirm or exclude the diagnosis?

  • 4. How would you manage this condition?

Answers

1. What abnormality does the computed tomogram show?

Answer

A 19 mm nodule is seen the right adrenal gland.

Discussion

A 19 mm nodule is seen in the right adrenal gland (figs 3 and 4). The gland is homogeneously hypodense, with a rounded margin suggestive of an adenoma. …

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