Transient ionized hypocalcemia and secondary hyperparathyroidism accompanying acute adrenal insufficiency.

OBJECTIVE To describe the hitherto unrecognized occurrence of transient ionized hypocalcemia with acute adrenal insufficiency and its therapy. METHODS We present three case reports with documented longitudinal laboratory findings. RESULTS Transient ionized hypocalcemia of acute illness has been noted in children and adults and is associated with increased mortality. Precipitating illnesses include gram-positive and gram-negative sepsis and staphylococcal toxic shock syndrome. We encountered three patients with transient ionized hypocalcemia associated with acute adrenal insufficiency. Similar to severely ill, transiently hypocalcemic patients without adrenal insufficiency, one patient demonstrated 25-hydroxyvitamin D deficiency, a second had minimal magnesium deficiency, and a third had no identifiable underlying abnormality. All three patients exhibited a transient increase in levels of serum intact parathyroid hormone and 1,25-dihydroxyvitamin D in response to ionized hypocalcemia, indicative of temporary secondary hyperparathyroidism. Two of the three patients were treated solely with glucocorticoids and intravenous administration of fluids, whereas the third received minimal intramuscularly administered magnesium and antibiotics in addition. All ultimately demonstrated a return to normal of serum total and ionized calcium, parathyroid hormone, and 1,25-dihydroxyvitamin D with no further treatment, even though one patient remained deficient in 25-hydroxyvitamin D. CONCLUSION On the basis of these cases, we conclude that acute adrenal insufficiency and its treatment must be added to the disorders associated with transient ionized hypocalcemia and that transient secondary hyperparathyroidism is characteristic of at least some of the patients.