A diabetic patient treated for hypertension develops tremors and twitches

Objective: To report an unusual but known cause of hypomagnesaemia-induced hypocalcaemia and review the relevant literature. Methods: We present the clinical and laboratory findings in a case of hypomagnesaemia induced-hypocalcaemia, and discuss the underlying mechanisms in light of the available literature. Results: After admission our patient described typical features of magnesium deficiency such as weakness, tremors and muscle twitches. He also had clinical signs of hypocalcaemia such as a pronounced carpal pedal spasm. Blood results revealed that he had low calcium and magnesium. This was further confirmed by another set of blood results. His vitamin D levels were normal at 25.2 pg/mL and 27.3 pg/mL. His parathyroid hormone was at 18.5 pg/mL (12–72). His urea and electrolytes were normal with sodium of 137 mmol/l, potassium of 3.8 mmol/l, creatinine of 93 mL/minute, and liver function tests in the normal range. Hypomagnesaemia is a common finding and has been reported to be present in nearly 12% of hospitalised patients. From a review of published reports, it is seen that most cases of hypomagnesaemia are due to gastrointestinal or renal losses, but it is also seen with excess alcohol consumption. Drugs such as proton pump inhibitors and, although not often reported, thiazide diuretics are known to cause hypomagnesaemia. The patient was on Indapamide for his hypertension. With replacement therapy, both his ion levels returned back to normal. Conclusion: Hypomagnesaemia is often usually associated with multiple biochemical abnormalities. The increasing use of diuretics and the introduction of potent preparations present a considerable risk for hypomagnesaemia induced-hypocalcaemia.