Hypophosphatemia in critically ill children: Prevalence and associated risk factors

Background. Hypophosphatemia is a disorder with potential complications and is often unrecognized in critically ill patients. Aims. To identify the prevalence of hypophosphatemia and risk factors associated to this disorder in critically ill children. Methods: In a prospective cohort study, 82 children admitted consecutively to a pediatric intensive care unit (ICU) were monitored regarding phosphorus serum levels during the first 10 days of admission. The following variables were analyzed as independent for hypophosphatemia: age, gender, diagnosis at admission, malnutrition, phosphorus intake, clinical severity score at admission (pediatric index of mortality 2) and daily scores (Pediatric Logistic Organ Dysfunction), sepsis, use of dopamine, furosemide and steroids, starvation period, and refeeding. Children with a z score of less than -2 of expected weight for age or body mass index (National Center for Health Statistics, 2000) were considered malnourished. Variables significantly associated with hypophosphatemia by bivariate analysis (p < 0.1) were included in a multiple logistic regression model. Results: The rate of hypophosphatemia was 61% during the first 10 days of pediatric ICU stay, and 12 patients developed hypophosphatemia during the study period. Malnutrition was present in 39.1% of patients, and the sera phosphorus concentration was significantly lower in malnourished than in well-nourished children (2.6 +/- 0.7 mg/dL vs. 3.5 +/- 0.8 mg/dL, p = 0.01). The multiple logistic regression model indicated the diagnosis of acute respiratory disease (odds ratio: 3.22; confidence interval: 1.03-10.1; p = 0.04), use of dopamine (odds ratio: 8.65; confidence interval: 1.58-47.3; p = 0.01), and malnutrition (odds ratio: 3.96; confidence interval: 1.19-13.3; p = 0.02) as independent risk factors for hypophosphatemia. None of the other potential risk factors discriminated for hypophosphaternia. Conclusions: Hypophosphatemia was common in the first 10 days of ICU hospitalization and was associated with the diagnosis of respiratory disease, use of dopamine, and malnutrition. These factors should be taken into account during clinical follow up of critically ill children, especially when these conditions are found together. (Pediatr Crit Care Med 2009; 10:234-238)