Hypomagnesemia in critically ill cancer patients: a prospective study of predictive factors

Hypomagnesemia is the most common electrolyte disturbance seen upon admissi on to the intensive care unit (ICU), Reliable predictors of its occurrence are not described. The objective of this prospective study was to determine factors predictive of hypomagnesemia upon admission to the ICU, In a singl e tertiary cancer center, 226 patients with different diagnoses upon enteri ng were studied, Hypomagnesemia was defined by serum levels <1.5 mg/dl. Dem ographic data, type of cancer, cause of admission, previous history of arrh ythmia, cardiovascular disease, renal failure, drug administration (particu larly diuretics, antiarrhythmics, chemotherapy and platinum compounds), pre vious nutrition intake and presence of hypovolemia were recorded for each p atient. Blood was collected for determination of serum magnesium, potassium , sodium, calcium, phosphorus, blood urea nitrogen and creatinine levels, U pon admission, 103 (45.6%) patients had hypomagnesemia and 123 (54.4%) had normomagnesemia. A normal dietary habit prior to ICU admission was associat ed with normal Mg levels (P = 0.007) and higher average levels of serum Mg (P = 0.002). Postoperative patients (N = 182) had lower levels of serum Mg (0.60 +/- 0.14 mmol/l compared with 0.66 +/- 0.17 mmol/l, P = 0.006). A ste pwise multiple linear regression disclosed that only normal dietary habits (OR = 0.45; CI = 0.26-0.79) and the fact of bring a postoperative patient ( OR = 2.42; CI = 1.17-4.98) were significantly correlated with serum Mg leve ls (overall model probability = 0.001), These findings should be used to id entify patients at risk for such disturbance, even in other critically ill populations.