Calcitonin gene- and parathyroid hormone-related peptides in preeclampsia:Effects of magnesium sulfate

Objective: To determine whether circulating levels of calcitonin gene-relat ed peptide (CGRP) and parathyroid hormone-related peptide (PTHrP) are alter ed in preeclampsia, and to assess the effects of magnesium sulfate therapy on circulating levels of these two peptides. Methods: The study population included 25 women with preeclampsia and 25 no rmotensive controls of similar gestational age. The effects of magnesium su lfate therapy were evaluated in 17 of the 25 preeclamptic women. Circulatin g levels of immunoreactive CGRP and PTHrP, including calcium, magnesium, an d phosphate in the maternal and umbilical cord serum were measured. Results: The frequency of preeclampsia subjects with nondetectable PTHrP (u nder 3 pg/mL) was significantly higher (92% versus 48%, P < .001), whereas maternal serum CGRP levels were significantly lower (50 +/- 19 versus 90 +/ - 23 pg/mL, P < .001). Similarly, the frequency of newborns with nondetecta ble PTHrP levels in umbilical serum was significantly higher (68% versus 36 %, P < .05), whereas the levels of CGRP were significantly lower (67 +/- 17 versus 79 +/- 16 pg/mL, P < .05). Magnesium sulfate treatment resulted in a significant increase in maternal circulating CGRP levels (64 +/- 17 versu s 47 +/- 18 pg/mL, P < .05) with no changes in PTHrP. Conclusion: Maternal circulating PTHrP and CGRP concentrations were signifi cantly lower in women with preeclampsia, which may contribute to the develo pment and maintenance of hypertension during pregnancy. Furthermore, magnes ium sulfate therapy increased the levels of CGRP in the maternal circulatio n. (Obstet Gynecol 2001;97: 893-7. (C) 2001 by The American College of Obst etricians and Gynecologists.).