title: Urinary corticotropin-releasing hormone immunoreactivity is elevated during human pregnancy.
abstract: Plasma corticotropin-releasing hormone immunoreactivity (CRH IR) rises with gestational age in women. In order to investigate the physiological changes of the hormone in pregnant women's urine, CRH IR was measured by radioimmunoassay in urine collected over a 24-hour period, a blood sample and a subsequent single collection of urine after the 24-hour collection (spot urine). Plasma CRH IR in pregnant subjects, 8682.8 +/- 2063.0 pg CRH IR/ml plasma (mean +/- SEM, n = 25), was significantly higher than that in the non-pregnant controls (7.2 +/- 1.6 pg/ml, n = 5; separate t = 4.21, p = 0.0003, d.f. = 24). Similarly, pregnant women had higher spot urine CRH IR - 54.6 +/- 15.5 pg/mumol creatinine (Cr) versus 5.0 +/- 0.5 pg/mumol Cr (separate t = 3.20, p = 0.0038, d.f. = 24.0) - and 24-hour urine CRH IR - 13.7 +/- 1.2 pg/mumol Cr compared with 7.7 +/- 0.8 pg/mumol Cr (separate t = 4.28, p = 0.003, d.f. = 24.4) than the non-pregnant cohort. The difference between urinary excretion of CRH IR as estimated by 24-hour urine (13.7 +/- 1.2 pg/mumol Cr) and spot urine (54.6 +/- 15.5 pg/mumol Cr) indicated that CRH IR in 24-hour urine may be degraded during storage. The weak associations between plasma and 24-hour urine CRH IR of pregnant women (correlation coefficient r = 0.34, p greater than 0.1), and total 24-hour urine and spot urine CRH IR (r = 0.25, p less than 0.1) further indicate CRH degradation. Plasma and spot urinary CRH IR, however, were strongly correlated (r = 0.80, p = 0.001). The total CRH IR excreted as estimated from the spot urine value (0.5 +/- 0.1 micrograms/day) compared with the total filtered load of CRH IR in the pregnant group (1306.9 +/- 324.6 micrograms/day) showed that 99.97% of the filtered CRH IR was reabsorbed or metabolized by the kidneys. Acidic gel chromatography of spot and 24-hour urine samples showed a CRH IR peak at CRH41 standard elution position (Kd = 0.5), indicating that the molecular form in urine is similar to the 41-residue standard. Pregnancy-induced hypertension correlated positively with plasma CRH IR (r = 0.62, p less than 0.001) and spot urine CRH IR (r = 0.46, p less than 0.01), and negatively with parity (r = -0.60, p less than 0.001). Plasma CRH IR and parity also negatively correlated (r = -0.41, p less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Centre for Maternal Health Research, Faculty of Medicine, Newcastle, New South Wales, Australia.
authors.forename: E C
authors.initials: EC
authors.lastname: Chan
authors.forename: M W
authors.initials: MW
authors.lastname: Brinsmead
authors.forename: S E
authors.initials: SE
authors.lastname: Chen
authors.forename: R
authors.initials: R
authors.lastname: Nanra
authors.forename: B
authors.initials: B
authors.lastname: Simm
authors.forename: M
authors.initials: M
authors.lastname: McLean
authors.forename: R
authors.initials: R
authors.lastname: Smith
mesh_terms: D003346:Corticotropin-Releasing Hormone / Q000097:blood / Q000652:urine*; D003404:Creatinine / Q000652:urine; D005260:Female; D005865:Gestational Age; D006801:Humans; D006973:Hypertension / Q000378:metabolism; D008403:Mass Screening; D007752:Obstetric Labor, Premature / Q000517:prevention & control; D010298:Parity; D011225:Pre-Eclampsia / Q000517:prevention & control; D011247:Pregnancy / Q000652:urine*; D011249:Pregnancy Complications, Cardiovascular / Q000378:metabolism; D011863:Radioimmunoassay
chemical_list: D003346:Corticotropin-Releasing Hormone; D003404:Creatinine