title: Migration is associated with lower total, but not free testosterone levels in South Asian men.
abstract: OBJECTIVE
  Serum testosterone measurement is an integral part of the endocrine assessment of men. Little is known about its variation in relation to migration. We examined within a South Asian group the effect of migration to the UK on androgen levels.
  
  
  METHODS
  Circulating testosterone and SHBG concentrations were measured in 97 Gujarati men resident in India and in 79 men from the same villages of origin living in Birmingham, UK. Free testosterone was calculated by Vermeulen's method. Insulin sensitivity (HOMA-S) was determined from paired fasting plasma intact insulin and glucose values.
  
  
  RESULTS
  Circulating testosterone was significantly lower in UK Gujarati men (17.2 nmol/l [15.7-18.7]) vs. Indian Gujarati men (21.7 [20.0-23.5]) (P = 0.0002) (age-adjusted median [95% CI]). There was no difference by migration status in circulating free testosterone. Sex hormone binding globulin (SHBG) levels were lower in UK migrants (16.8 nmol/l [15.5-18.1]) than in nonmigrants (21.9 nmol/l [20.5-23.3]) (P < 0.0001). Testosterone level correlated positively with insulin sensitivity (HOMA-S) (rho 0.16, P = 0.04). In multivariate analysis, total testosterone was independently and positively associated with logSHBG (normalized beta (beta) = 0.29, P = 0.002) and independently and negatively with waist circumference (beta = -0.19, P = 0.04), in a model also including height, age, migration status, leptin and fasting insulin.
  
  
  CONCLUSIONS
  Lower circulating testosterone in UK Gujarati men and its association with markers of insulin sensitivity suggest a profound influence of body composition change with migration on testosterone levels. The lower SHBG in this group restores parity in free testosterone. Account should be taken of SHBG in interpreting testosterone levels in men, as well as in women.
authors: Department of Endocrinology, University of Manchester, Salford NHS Trust, Salford, UK. Adrian.Heald-2@manchester.ac.uk
authors: A H
authors: AH
authors: Heald
authors: J
authors: J
authors: Patel
authors: S G
authors: SG
authors: Anderson
authors: A
authors: A
authors: Vyas
authors: A
authors: A
authors: Rudenski
authors: E
authors: E
authors: Hughes
authors: N C
authors: NC
authors: Panja
authors: A
authors: A
authors: Ullah
authors: D
authors: D
authors: Prabhakaran
authors: S
authors: S
authors: Reddy
authors: P
authors: P
authors: Durrington
authors: J M
authors: JM
authors: Gibson
authors: I
authors: I
authors: Laing
authors: D
authors: D
authors: Bhatnagar
authors: J K
authors: JK
authors: Cruickshank
mesh_terms: D000375:Aging; D044466:Asian People; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D001823:Body Composition; D001827:Body Height; D016022:Case-Control Studies; D004641:Emigration and Immigration; D004739:England; D006801:Humans; D007194:India / Q000208:ethnology; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D020738:Leptin / Q000097:blood; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood*
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D020738:Leptin; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D007334:Insulin-Like Growth Factor I