We present a patient with leptospirosis infection who presented septic shock with multiple-organ dysfunction syndrome, severe rhabdomyolysis and acute myocarditis. He developed biphasic blood calcium pattern with hypocalcemia in the oliguric phase followed by hypercalcemia during the recovery diuretic phase in the context of rhabdomyolysis and oliguric acute kidney injury. Meanwhile, he developed an extensive calcification of the myocardium. Severe renal magnesium wasting was observed during the convalescence phase. Follow-up showed progressive resorption and later almost total disappearance of the calcific deposits in the heart by the 18th month after discharge. Renal magnesium wasting decreased gradually, but yet persisted beyond the 18th and was normalized only by the 36th month after discharge. We discuss the pathophysiologic mechanisms involved in the myocardial calcification and renal magnesium wasting and suggest a possibility of a contributing role of magnesium renal wasting in mobilization of calcium deposits out of myocardium.