A 48-year-old healthy, normotensive male was referred by GP due to incidental finding of hypokalaemia of 2.5 mmol/L on routine blood testing. The patient was initially treated with oral potassium supplements with little effect. Biochemical investigations in the endocrine clinic demonstrated mild metabolic alkalosis, eunatraemia, mild hypomagnesaemia 0.6 mmol/L and hypercalcaemia of 2.84 mmol/L with hypophosphataemia of 0.53 mmol/L. PTH was high at 350 ng/L. Renin and aldosterone levels were elevated suggesting secondary hyperaldosteronism.There was no evidence of steroid excess on ODDST. Calcium excretion was not initially measured. The neck imaging confirmed a large (2.9×0.9×2.1 cm) parathyroid adenoma. At this stage it was thought that primary hyperparathyroidism was the cause of hypokalaemia (incomplete distal RTA). Following the parathyroid surgery, the calcium, PTH and potassium levels have normalised. Subsequently, the potassium level was noted to be low again and remained low (2.53.5 mmol/L) despite oral potassium supplements. At this stage the diagnosis of Gitelman syndrome was made. The patient has been taking Amiloride with good effect.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.