Secondary hyperparathyroidism is associated with postpartum blood pressure in preeclamptic women and normal pregnancies

Background: Preeclampsia has been associated with features of secondary hyperparathyroidism. In this study, we examine the relationships of calcium metabolism with blood pressure (BP) in preeclamptic women and in a control group of normal (NORM) pregnancies in the postpartum. Methods: Sixty-three consecutive preeclamptic women (age 35 ± 6 years) were studied 4 weeks after delivery. We collected clinical and lab information on pregnancy and neonates and measured plasma and urinary calcium and phosphate, plasma parathyroid hormone (PTH) and 25-hydroxy vitamin D [25(OH)D], and performed 24-h ambulatory BP monitoring. BP and calcium metabolism of 51 preeclamptic were compared with 17 NORM pregnant women that matched for age, race, and postpartum BMI. Results: 25(OH)D deficiency (<10 ng/ml) was found in 3% of preeclamptic women, insufficiency (10–30 ng/ml) in 67%, and NORM values (31–100 ng/ml) in the remaining 30%. Elevated plasma PTH (≥79 pg/ml) was found in 24% of preeclamptic women who had 25(OH)D plasma levels of 21.4 ± 8.3 ng/ml. In these women, PTH levels was independently associated with 24-h SBP and DBP and daytime and night-time DBP. Prevalence of nondippers and reverse dippers was elevated (75% and 33%, respectively). No associations between calcium metabolism and neonates’ characteristics of preeclamptic women were observed. Prevalence of vitamin D deficiency and insufficiency and of elevated plasma PTH levels were comparable in matched groups. Considering preeclamptic women and matched controls as a whole group, office SBP and DBP levels were associated with PTH independently of preeclampsia and other confounders. Conclusion: Features of secondary hyperparathyroidism are common in the postpartum. Preeclampsia and increased PTH levels were both independent factors associated with increased BP after delivery, and both might affect the future cardiovascular risk of these women.