Hormone replacement therapy in postmenopausal women: urinary N-telopeptide of type I collagen monitors therapeutic effect and predicts response of bone mineral density.
OBJECTIVE
To assess the ability of the urinary N-telopeptide of type I collagen (NTx) to monitor and predict therapeutic effects of hormone replacement therapy (HRT) in postmenopausal women.


METHODS
To assess the relationship between baseline or change in NTx (predictive variable), and change in lumbar and hip bone mineral density (BMD; outcome variable), we conducted a 2-year randomized controlled study at academic university and private practice medical centers in 236 healthy women 1 to 3 years postmenopausal; 227 women completed the study. Women received estrogen plus progesterone plus calcium (treated group) or calcium alone (control group).


RESULTS
In the treated group NTx significantly (P < 0.0001) decreased, and spine and hip BMD significantly (P < 0.00001 and P < 0.005, respectively) increased; in the control group NTx did not change but BMD decreased significantly (P < 0.01). Subjects in the highest quartiles for baseline NTx (67 to 188 units) or decreasing NTx (-66% to -87%) through 6 months demonstrated the greatest gain in BMD in response to HRT (P < 0.05 and P < 0.005). For every increase of 30 units in baseline NTx the odds of gain in BMD in response to HRT increased by a factor of 5.0 (95% confidence interval [CI] 1.9 to 13.3); for every 30% decrease in NTx through 6 months, the odds of gaining BMD in response to HRT increased by a factor of 2.6 (95% CI 1.6 to 4.4). In the control group an increase of 30 units in mean NTx across the study indicated a higher odds of losing BMD by a factor of 3.2 (95% CI 1.6 to 6.5). A high baseline NTx (> 67 units) indicated a 17.3 times higher risk of BMD loss if not treated with HRT.


CONCLUSIONS
These data support the clinical utility of NTx to monitor the antiresorptive effect of HRT in recently postmenopausal women, and to predict changes in BMD in response to HRT.
Chesnut
C H
CH
University of Washington Medical Center, Seattle 98195-6113, USA.
Bell
N H
NH
Clark
G S
GS
Drinkwater
B L
BL
English
S C
SC
Johnson
C C
CC
Notelovitz
M
M
Rosen
C
C
Cain
D F
DF
Flessland
K A
KA
Mallinak
N J
NJ
D015502:Absorptiometry, Photon; D000328:Adult; D015519:Bone Density / Q000187:drug effects*; D002119:Calcium Carbonate / Q000627:therapeutic use; D003094:Collagen / Q000652:urine*; D024042:Collagen Type I; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000627:therapeutic use; D005260:Female; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D015999:Multivariate Analysis; D010455:Peptides / Q000652:urine*; D017698:Postmenopause / Q000652:urine*; D011237:Predictive Value of Tests; D011374:Progesterone / Q000627:therapeutic use
D024042:Collagen Type I; D004967:Estrogens; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D011374:Progesterone; D003094:Collagen; D002119:Calcium Carbonate