Hypophosphatemia occurs in 40 to 60% of patients with
acute malaria, and in many other conditions associated with elevations of body temperature. To determine the prevalence and causes of
hypophosphatemia in patients with
malaria, we retrospectively studied all adults diagnosed with
acute malaria during a 12-year period. To validate our findings, we analyzed a second sample of
malaria patients during a subsequent 10-year period. Serum
phosphorus correlated inversely with temperature (n = 59, r = -0.62; P<0.0001), such that each 1 degrees C increase in body temperature was associated with a reduction of 0.18 mmol/L (0.56 mg/dL) in the serum
phosphorus level (95% confidence interval: -0.12 to -0.24 mmol/L [-0.37 to -0.74 mg/dL] per 1 degrees C). A similar effect was observed among 19 patients who had repeat measurements of serum
phosphorus and temperature. In a multiple linear regression analysis, the relation between temperature and serum
phosphorus level was independent of blood pH, PCO2, and serum levels of
potassium, bicarbonate,
calcium,
albumin, and
glucose. Our study demonstrates a strong inverse linear relation between body temperature and serum
phosphorus level that was not explained by other factors known to cause
hypophosphatemia. If causal, this association can account for the high prevalence of
hypophosphatemia, observed in our patients and in previous studies of patients with
malaria. Because
hypophosphatemia has been observed in other clinical conditions characterized by
fever or
hyperthermia, this relation may not be unique to
malaria. Elevation of body temperature should be added to the list of causes of
hypophosphatemia.