Endocrine Abstracts

Background: Hypokalaemia is frequently encountered in endocrinology practice; yet it is important to be aware of rarer causes, their investigation and management. Gitelman’s syndrome is an extremely rare cause of hypokalaemia, with prevalence estimated at 25 cases per one million population. We report a case of likely Gitelman’s syndrome, presenting with hypokalaemia, metabolic alkalosis and secondary hyperaldosteronism.

Case: A 30-year-old gentleman was referred by his family physician with tiredness and hypokalaemia (serum potassium - 2.6 mmol/L [3.5-5.3]). Admission bloods confirmed hypokalaemia and hypomagnesaemia (2.4 mmol/L and 0.49 mmol/L (0.70-1.00) respectively). Given his young age, absence of comorbidities or malnutrition, he was assessed for renal tubulopathies. Further investigations showed metabolic alkalosis (serum bicarbonate 33 mmol/L [22-29]), raised aldosterone (710 pmol/l [>631]) and renin (11.0 nmol/L/h [03 -2.2]), with high urinary output of magnesium (10.9 mmol [2.5-6.5]), potassium (169 mmol [25 -125]), and low 24-hour urinary calcium (1.5 mol [2.5-7.5]). These all suggest a thiazide-sensitive NaCl cotransporter (NCC) channelopathy; with likely diagnosis of Gitelman’s Syndrome. On intravenous potassium chloride followed by oral Sando-K (600 milligrams potassium chloride and 400 milligrams potassium bicarbonate - two tablets three times a day) and Spironolactone (50 milligrams a day), his hypokalaemia improved. His serum magnesium levels were more resistant to treatment, remaining low on intravenous or oral magnesium aspartate (0.42 - 0.45 mmol/l). After reviewing the latest guidelines and liaising with international experts, his treatment was switched to magnesium lactate (Magnalac 84 milligrams), and potassium chloride (PotaChlor MR 600milligrams), which thus improved his electrolyte levels. His genetic analysis for renal tubulopathies is awaited.

Conclusion: It is important to have a broad clinical suspicion when coming across common electrolyte disturbances. Our case of likely Gitelman’s Syndrome raises awareness of this rare condition and highlights the challenges incurred in its assessment and treatment.