Serum Calcium and Phosphate Disturbances During Rehydration in Acute Dehydrating Gastroenteritis

Summary Alterations in serum ionized and total calcium, magnesium, and phosphate concentrations, during recovery from acute dehydrating gastroenteritis, were studied. Fifteen children with acute dehydrating gastroenteritis had serum concentrations of ionized and total calcium, magnesium, phosphate, sodium, potassium, chloride, urea, creatinine, and albumin, as well as acid‐base status, evaluated during rehydration and up to 72‐h postadmission. The total serum calcium corrected for albumin did not change significantly during rehydration and remained within the normal range. Although serum ionized calcium fell significantly at 24 and 72 h, its concentration was not sufficiently decreased to cause symptomatic hypocalcemia. Serum ionized calcium correlated significantly with pH (r −0.57), bicarbonate (r = −0.63), and albumin (r = +0.65), but not with total serum calcium, magnesium, and phosphate. Serum magnesium remained within the normal range during the study period. Serum phosphate was increased on admission (2.64 ± 0.77 mmol/L), decreased by 12 h (to 0.84 ± 0.32 mmol/L), and then followed by a gradual increase. This study suggests that changes in serum ionized calcium in dehydrating gastroenteritis are not of clinical significance. However, changes in serum phosphate concentration need further evaluation.