The effects of serum testosterone, estradiol, and sex hormone binding globulin levels on fracture risk in older men.
BACKGROUND
The relationship between sex steroids and fracture is poorly understood.


OBJECTIVE
The objective of the study was to examine associations between nonvertebral fracture risk and bioavailable estradiol (bioE2), bioavailable testosterone (bioT), and SHBG.


METHODS
This was a case-cohort study.


METHODS
The Osteoporotic Fractures in Men Study (MrOS) was conducted in a prospective U.S. cohort in 5995 community-dwelling men 65 yr old or older.


METHODS
Participants included a subcohort of 1436 randomly chosen white men plus all 446 minorities and all those with incident hip and other nonvertebral fractures.


METHODS
Baseline testosterone and estradiol were measured by mass spectrometry (MS) and SHBG by RIA.


RESULTS
Men with the lowest bioE2 (<11.4 pg/ml) or highest SHBG (>59.1 nm) had greater risk of all nonvertebral fractures [adjusted hazard ratio (HR) [95% confidence interval]: 1.5 (1.2-1.9) and 1.4 (1.1-21.8), respectively]. Men with the lowest bioT (<163.5 ng/dl) had no increased fracture risk after adjustment for bioE2 [adjusted HR 1.16 (0.90-1.49)]. A significant interaction between SHBG and bioT (P = 0.03) resulted in men with low bioT and high SHBG having higher fracture risk [HR 2.1 (1.4-3.2)]. Men with low bioE2, low bioT, and high SHBG were at highest risk [HR 3.4 (2.2-5.3)].


CONCLUSIONS
Older men with low bioE2 or high SHBG levels are at increased risk of nonvertebral fracture. When SHBG levels are high, men with low bioT levels have higher risk. The strongest association occurred when all measures were considered in combination.
LeBlanc
Erin S
ES
Bone and Mineral Unit, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
Nielson
Carrie M
CM
Marshall
Lynn M
LM
Lapidus
Jodi A
JA
Barrett-Connor
Elizabeth
E
Ensrud
Kristine E
KE
Hoffman
Andrew R
AR
Laughlin
Gail
G
Ohlsson
Claes
C
Orwoll
Eric S
ES
D000368:Aged; D015519:Bone Density; D015331:Cohort Studies; D004958:Estradiol / Q000097:blood*; D050723:Fractures, Bone / Q000209:etiology*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012306:Risk; D012738:Sex Hormone-Binding Globulin / Q000032:analysis*; D013739:Testosterone / Q000097:blood*
D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol