Parathyroid hormone secretion in women in late menopause submitted to EDTA-induced hypocalcemia.
OBJECTIVE
The physiological role of parathormone (PTH) in the maintenance of bone mass in humans has not been fully defined. The main objective of the present study was to evaluate basal and EDTA-stimulated PTH levels in young women (Group Y=30.9 years, N=7) and in women in late menopause (Group M=64.7 years, N=7) and their relationship to bone mineral density.


METHODS
The PTH secretion test was performed by induction of hypocalcemia through intravenous administration of EDTA for 2h. Blood samples were collected every 10 min and used for ionic calcium and PTH measurements. During the basal period, an additional sample was collected for the determination of osteocalcin, FSH, and estradiol. A sample of early morning second voided urine was collected for analysis of deoxypiridinoline and creatinine as well as bone mass density (BMD) was determined by dual X-ray energy absorptiometry (DEXA).


RESULTS
The aged patients presented lower femoral BMD (Y=0.860 g/cm(2) vs. M=0.690 g/cm(2), p<0.01), with four of them having a T score lower than -2.5 S.D. Basal, and during the EDTA infusion, PTH values were similar in both groups. However, among aged volunteers, the rise in PTH levels was higher for subjects with normal bone mass (NM: peak=236 pg/ml) than for subjects with osteoporosis (OM: peak=134.4 pg/ml).


CONCLUSIONS
The present results suggest that PTH can have a modulating effect on the rate of bone loss during late menopause.
Department of Gynecology and Obstetrics, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Avenue Bandeirantes 3900, Ribeirão Preto, São Paulo, Brazil.
L C R
LC
Pereira
F A
FA
Pereira
M F S
MF
Sá
M C
MC
Foss
F J A
FJ
de Paula
D015502:Absorptiometry, Photon; D000328:Adult; D000367:Age Factors; D000368:Aged; D015519:Bone Density; D004492:Edetic Acid / Q000008:administration & dosage; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000139:chemically induced*; D008593:Menopause; D008875:Middle Aged; D010024:Osteoporosis / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood* / Q000378:metabolism*
D010281:Parathyroid Hormone; D004492:Edetic Acid