Racial variation in sex steroid hormones and the insulin-like growth factor axis in umbilical cord blood of male neonates.
BACKGROUND
To address whether umbilical cord blood concentrations of sex steroid hormones and the insulin-like growth factor (IGF) axis differ between African-American and White male neonates.


METHODS
In 2004 and 2005, venous cord blood samples were collected from 75 African-American and 38 White male full-term uncomplicated births along with birth weight, placental weight, mother's age and parity, and time of birth. Testosterone, androstanediol glucuronide, estradiol, and sex hormone binding globulin (SHBG) were measured by immunoassay, and IGF-I, IGF-2, and IGF binding protein (BP)-3 by ELISA. Crude and multivariable-adjusted geometric mean concentrations were computed.


RESULTS
Androstanediol glucuronide, estradiol, and SHBG concentrations did not differ by race; however, the molar ratio of testosterone to SHBG was higher in African-American than White male babies after adjustment (P = 0.01). Both before and after adjustment, Whites had higher concentrations of IGF-I (adjusted; White, African-American, 93.1, 71.9 ng/mL), IGF-2 (537.3-474.8 ng/mL), and IGFBP-3 (1,673-1,482 ng/mL) than African-Americans (P < 0.05), although the molar ratio of IGF-I plus IGF-2 to IGFBP-3 did not differ by race.


CONCLUSIONS
The higher cord blood testosterone to SHBG ratio in African-American compared with White male babies after taking into account maternal and birth factors is compatible with the hypothesis that differences in androgen levels in utero contribute to their higher prostate cancer risk, although we would have expected crude differences as well. Lower cord blood IGF-I and IGF-2 levels in African-American compared with White male babies are not consistent with the hypothesis that differences in growth factor levels contribute to their higher prostate cancer risk.
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
Sabine
S
Rohrmann
Catherine G
CG
Sutcliffe
Jessica L
JL
Bienstock
Deborah
D
Monsegue
Folasade
F
Akereyeni
Gary
G
Bradwin
Nader
N
Rifai
Michael N
MN
Pollak
Tanya
T
Agurs-Collins
Elizabeth A
EA
Platz
D000328:Adult; D044383:Black People; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D007231:Infant, Newborn; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008423:Maternal Age; D010865:Pilot Projects; D044465:White People; D001741:Black or African American
D012739:Gonadal Steroid Hormones; D007334:Insulin-Like Growth Factor I