Hypocalcemia and hyperphosphatemia in severely dehydrated children with and without convulsions

Abstract

Tetanic convulsions are not uncommon among severely dehydrated children in the developing countries. This raises the question whether these children have disturbances in the homeostasis of divalent ions. Serum values are reported of calcium, magnesium, phosphorus, sodium and potassium, as well as blood pH in children below 3 years of age with acute watery diarrhoea and with an estimated weight loss of about 10%. The study was performed on dehydrated children with (DC) or without (D) convulsions. Values were obtained on admission and following rehydration therapy (RT). On admission serum calcium was low in both D and DC children. Serum phosphorus was likewise elevated in both D and DC children. Serum magnesium was slightly elevated in the DC but not in the D group. No patient had hypernatremia. During RT, serum calcium increased significantly and serum phosphorus decreased significantly in D and DC children. Serum calcium showed a significant inverse correlation with serum phosphorus and a significant direct correlation with blood pH. Treatment of DC children with i.v. calcium and i.m. magnesium had no immediate effect on the convulsions. Our conclusion is that severely dehydrated children will develop hypocalcemia. The cause may be a redistribution of calcium into the cells, parallelled by a redistribution of phosphorus from the intra- to the extracellular space.