ISSN:
1432-0827
Keywords:
Parathyroid hormone
;
Pregnancy
;
Nephrogenous cAMP
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
,
Physics
Notes:
Summary Parathyroid hormone (PTH) metabolism in pregnancy has not been clearly defined. Studies have reported either increased or unchanged values of immunoreactive PTH (iPTH). However, iPTH levels do not necessarily correlate with hormonal bioactivity due to the presence of immunoreactive but nonbioactive PTH fragments. In this study we evaluated PTH metabolism in the third trimester of pregnancy by determining iPTH blood levels as well as the biological effects of PTH, assessed by tubular maximum phosphate reabsorption (TmP) and nephrogenous cAMP (ncAMP) excretion, in 10 young, healthy pregnant patients (mean gestational age 35 weeks) and 10 young, healthy age-matched female controls. Pregnancy was associated with a significant increase in creatinine clearance (146±13 vs 106±9 ml/min,P〈0.01), and a significant decrease in total fasting serum calcium (8.4±0.1 vs 9.0±0.1 mg/dl,P〈0.001) and serum albumin (3.6±0.1 vs 4.2±0.1 g/dl,P〈0.001). There was no significant difference in iPTH (3.7±0.4 vs 4.3±0.5 µlEq/ml), serum phosphorus (3.6±0.1 vs 3.8±0.2 mg/dl), TmP (3.61±0.13 vs 3.75±0.25 mg/100 ml GFR), or ncAMP (1.68±0.20 vs 1.88±0.23 nmoles/100 ml GFR) between the two groups. Pregnancy was attended by a significant increase in fasting urinary calcium to creatinine ratio (0.14±0.03 vs 0.06±0.01,P〈0.05), an index of bone resorption. The data suggest that the biological effects of PTH are unchanged in pregnancy, and that reported increments in 1,25(OH)2 vitamin D in pregnancy are not regulated by changes in either PTH, calcium, or phosphate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02411200
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