Pseudohyperphosphatemia in children treated with liposomal amphotericin B.

Purpose: The results of a study to determine the frequency of pseudohyperphosphatemia in a sample of pediatric patients treated with i.v. liposomal amphotericin B are reported.

Methods: A single-site retrospective study was conducted to identify evidence of pseudohyperphosphatemia in the medical records of patients 18 years of age or younger who received at least five doses of amphotericin B liposome; the maximum dose was calculated for each regimen and categorized as either ≤5 or >5 mg/kg/day. The primary objective was to ascertain the rate of pseudohyperphosphatemia (i.e., abnormally high serum phosphate without elevated serum calcium). The secondary objective was to compare rates of pseudohyperphosphatemia at the higher and lower amphotericin B dosage levels. A multivariate generalized estimating equation (GEE) regression model was used to identify potential predictors of pseudohyperphosphatemia.

Results: Data were collected on 72 courses of amphotericin B liposome administered during a 13-month period to 47 patients; based on a review of chart notations and clinical data, it was determined that 36 regimens (50%) involved pseudohyperphosphatemia. The GEE model revealed no significant association between pseudohyperphosphatemia and any evaluated variable, including age, weight, duration of therapy, and concurrent use of medications known to alter serum phosphorus.

Conclusion: In children receiving amphotericin B liposome, half of the regimens were associated with pseudohyperphosphatemia. Although no factors were found to predict pseudohyperphosphatemia, on average, patients who developed the abnormality were significantly older and heavier and received a significantly higher absolute initial dosage of amphotericin B liposome than those who did not develop the condition.