CALCIUM AND CALCIOTROPIC HORMONES IN TRANSIENT - HYPERTENSION OF PREGNANCY VERSUS PREECLAMPSIA

Objective: Women with preeclampsia (PE) have markedly reduced urinary calcium excretion compared to normotensive, pregnant controls (NT). Th is abnormality in PE is accompanied by significantly reduced serum ion ized calcium, increased parathyroid hormone, and reduced 1,25(OH)(2)-v itamin D levels. Urinary calcium in women with transient hypertension of pregnancy (THP) may be normal, but serum calcium and calciotropic h ormones have never been reported. We set out to determine whether calc ium and calciotropic hormones differed between women with THP and PE. Methods: Third-trimester women with THP were studied and compared to v alues previously reported but concurrently measured for NT and PE. Uri nary calcium, sodium, creatinine, and protein in conjunction with seru m total and ionized calcium, intact parathyroid hormone (PTH), 25(OH)- vitamin D, 1,25(OH)(2)-vitamin D, and phosphate were measured in these women. Major Outcome Measure: Our hypothesis was that women with PE a nd THP could be distinguished on the basis of urine and serum calcium and calciotropic hormones. Results: Urinary calcium excretion in women with THP was remarkably similar to women with NT but significantly hi gher than women with PE (6.6 +/- 1.3 vs. 6.5 +/- 0.7 vs. 2.3 +/- 0.4 m mol/day, P = 0.002, respectively). Total serum calcium was not differe nt among the three groups; however, serum ionized calcium in women wit h THP was comparable to that in NT women but significantly higher than that in PE women (1.26 +/- 0.01 vs. 1.26 +/- 0.01 vs. 1.22 +/- 0.01 m u mol/L, respectively, P = 0.03). PTH levels were similar for THP and NT but were significantly lower than PE (17.4 +/- 2.8 vs. 15.4 +/- 2.8 vs. 31.7 +/- 4.1 ng/L, P = 0.00008). Measurements of 1,25(OH)(2)-vita min D were not significantly different among the three groups (THP: 22 6 +/- 34, NT: 220 +/- 13, PE: 162 +/- 19 pmol/L; P = 0.19, ANOVA), but direct comparison of NT and PE was still significantly different as r eported previously (P = 0.019, t test). Conclusion: These results prov ide further evidence that THP and PE may represent distinct and potent ially biochemically distinguishable diseases.