Erythrocyte cation metabolism in preeclampsia.

To determine if there are abnormalities in cellular cation regulation in pregnancy-induced hypertension, erythrocyte intracellular levels of calcium, magnesium, sodium, and potassium and circulating parathyroid hormone and "endoxin" were examined in 13 women with pregnancy-induced hypertension and 34 control subjects matched for gestational age (greater than or equal to 35 weeks). Both endoxin and parathyroid hormone levels were higher in patients with pregnancy-induced hypertension than in control subjects (endoxin, 294 +/- 34 vs. 210 +/- 19 pg/ml, p less than 0.05; parathyroid hormone, 0.65 +/- 0.05 vs. 0.60 +/- 0.03 ng/ml); the increase was significant only for endoxin. Intracellular calcium was higher in the patients with pregnancy-induced hypertension (0.033 +/- 0.010 vs. 0.015 +/- 0.001 mEq/L, p less than 0.05, in the patients with pregnancy-induced hypertension and control patients, respectively) but intracellular sodium, potassium, and magnesium levels were not different. This intracellular calcium elevation may be caused directly by the increase in parathyroid hormone or indirectly by the observed elevation in endoxin. Our data indicate that the observed effect is specific because no changes in intracellular sodium, potassium, or magnesium levels were found.