See the ECG Tutorial section on QT interval to learn how this is measured. Multiple medications, electrolyte abnormalities (hypocalcemia, hypomagnesemia and hypokalemia) and certain disease states ...

Hypomagnesemia is associated with hypoparathyroidism (hypoPT) because magnesium is required for efficient synthesis and secretion of parathyroid hormone (PTH). Hypomagnesemia associated with ...