Concurrent Gitelman Syndrome-like Tubulopathy and Grave's Disease

Gitelman syndrome (GS) is a rare autosomal recessive disorder characterized by the loss of function mutation of the solute carrier family-12 member-3 (SLC12A3) gene, encoding for sodium-chloride cotransporter of the distal convolute tubule. GS is characterized by hypokalemia, hypomagnesemia, metabolic alkalosis, and hypocalciuria. GS-like syndrome has been described rarely. Hyperthyroidism due to Grave's disease (GD) is characterized by the presence of autoantibodies to thyrotropin receptors. Concurrent occurrence of GS and GD is rarely reported, that too exclusively from far-east Asian populations. We describe a case of a 45-year-old man who presented with severe muscle weakness; the evaluation showed volume depletion, hypokalemia, hypomagnesemia, renal potassium and magnesium wasting, metabolic alkalosis, and hypocalciuria. He was also detected to have GD at the time of presentation. Genetic evaluation revealed a mutation in transient receptor potential melastatin 4 (TRPM4) gene. The clinical significance of this mutation in our patient remains unclear.