Hypocalcemia: A pervasive metabolic abnormality in the critically ill

Hypocalcemia has been reported in critically III patients, most commonly in association with sepsis syndrome. However, the severity and Incidence of h ypocalcemia in nonseptic but critically ill patients has not been well defi ned. Therefore, the goal of this study was to identify and compare the freq uency and degree of hypocalcemia in critically ill patients with differing underlying illnesses (those admitted to medical, surgical, trauma, neurosur gical, burn, respiratory, and coronary Intensive care units [ICUs]; group A ; n = 99). Results were compared with the frequency and degree of hypocalce mia in non-critically ill ICU patients (initially admitted to an ICU but di scharged within 48 hours; group B; n = 50) or hospitalized non-ICU patients (group C; n = 50). Incidences of hypocalcemia (ionized calcium [Ca] < 1.16 mmol/L [less than normal]) were 88%, 66%, and 26% for groups A, B, and C, respectively (P < 0.001). In group A, the frequency of hypocalcemia did not depend on the ICU setting or presence of sepals. However, the occurrence o f hypocalcemia correlated with both Acute Physiology and Chronic Health Eva luation II score (r = -0.39; P < 0.001) and patient mortality (eg, hazard r atio for death, 1.65 for Ca decrements of 0.1 mmol/L; P < 0.002). Hypomagne semia, number of blood transfusions, and presence of acute renal failure we re each associated with depressed Ca levels. A weak association (r = -0.12; P = 0.09) was noted between serum Ca level and QT interval. Clinical conce rn stemming from hypocalcemia was underscored by the substantial use of int ravenous (IV) Ca therapy (similar to2 to 3 g IV). We conclude that hypocalc emia is extremely common in hospitalized patients (up to 88%) and correlate s with severity of illness, but not with a specific illness per se. Whether it directly impacts patient survival remains unknown. Resolution of this i ssue appears to be critical because of the frequency with which it leads to high-dose IV Ca therapy. (C) 2001 by the National Kidney Foundation, Inc.