Ethnic differences in male reproductive hormones and relationships with adiposity and insulin resistance in older men.
OBJECTIVE
To assess ethnic differences in male reproductive hormone levels and to determine whether any differences are explained by adiposity, insulin resistance (IR) or comorbidities in older men.


METHODS
Multi-ethnic cross-sectional observational study.


METHODS
Community dwelling middle-aged and elderly men residing in the UK aged 40-84 years of South Asian (SA; n = 180), White European (WE; n = 328) or African Caribbean (AC; n = 166) origin.


METHODS
Measured testosterone (T), calculated free T (cFT), sex hormone-binding globulin and LH in SA, WE and AC men along with an assessment of body composition, IR, lifestyle factors and medical conditions.


RESULTS
Age-adjusted mean T and cFT levels were lower in SA men when compared to WE and AC men (mean (SEM) T: SA: 14·0 ± 0·4; WE: 17·1 ± 0·3; AC: 17·2 ± 0·5 nmol/l, P < 0·001; cFT: SA: 283 ± 7; WE: 313 ± 5; AC: 314 ± 8 pmol/l, P < 0·006). Compared to WE and AC men, SA men had higher levels of body fat, IR, comorbidities and diabetes. After adjusting for body fat, IR and other confounders, T levels in SA men remained lower than in WE men (P = 0·04) but ethnic differences in cFT became nonsignificant. LH levels were higher in SA than WE men in age-adjusted and fully adjusted models.


CONCLUSIONS
T and cFT are lower in SA men than in WE and AC men. Whether ethnic-specific reference ranges for T and cFT might be appropriate in clinical practice requires further investigation. Ethnic differences in cFT, but not T, appear to be, more readily, explained by ethnic differences in adiposity, thus providing insights into potential pathophysiological mechanisms.
Manchester Academic Health Sciences Centre, Faculty of Medical and Human Sciences, Institute of Human Development, Centre for Endocrinology and Diabetes, Andrology Research Unit, University of Manchester, Manchester, UK.
Robert J A H
http://orcid.org/0000-0003-0769-5899
RJ
Eendebak
Manchester Academic Health Sciences Centre, Faculty of Medical and Human Sciences, Institute of Human Development, Centre for Endocrinology and Diabetes, Andrology Research Unit, University of Manchester, Manchester, UK.
Agnieszka
A
Swiecicka
Complex Chemical Systems Group, School of Chemistry, University of Glasgow, Glasgow, UK.
Piotr S
PS
Gromski
Arthritis Research UK Centre for Epidemiology & NIHR Manchester Musculoskeletal Biomedical Research Unit, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK.
Stephen R
SR
Pye
Arthritis Research UK Centre for Epidemiology & NIHR Manchester Musculoskeletal Biomedical Research Unit, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK.
Terence W
TW
O'Neill
Department of Geography and Sustainable Development, School of Geography and Geosciences, University of St. Andrews, Saint Andrews, UK.
Alan
A
Marshall
Department of Clinical Biochemistry, University South Manchester Hospital, Manchester, UK.
Brian G
BG
Keevil
Faculty of Humanities, Cathie Marsh Institute for Social Research, University of Manchester, Manchester, UK.
Gindo
G
Tampubolon
School of Chemistry, Manchester Institute for Biotechnology, University of Manchester, Manchester, UK.
Royston
R
Goodacre
Manchester Academic Health Sciences Centre, Faculty of Medical and Human Sciences, Institute of Human Development, Centre for Endocrinology and Diabetes, Andrology Research Unit, University of Manchester, Manchester, UK.
Frederick C W
FC
Wu
Manchester Academic Health Sciences Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester Diabetes Centre, University of Manchester, Manchester, UK.|Faculty of Medical and Human Sciences, Institute of Human Development, Endocrinology and Diabetes Research Group, University of Manchester, Manchester, UK.
Martin K
MK
Rutter
D050154:Adiposity / Q000208:ethnology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000208:ethnology*; D003430:Cross-Sectional Studies; D006801:Humans; D007333:Insulin Resistance / Q000208:ethnology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism*; D006113:United Kingdom / Q000208:ethnology
D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D007986:Luteinizing Hormone