A1 Refereed original research article in a scientific journal
Larger testes and higher inhibin B levels in Finnish than in Danish newborn boys
Authors: Main KM, Toppari J, Suomi AM, Kaleva M, Chellakooty M, Schmidt IM, Virtanen HE, Boisen KA, Kai CM, Damgaard IN, Skakkebaek NE
Publication year: 2006
Journal: Journal of Clinical Endocrinology and Metabolism
Journal name in source: The Journal of clinical endocrinology and metabolism
Journal acronym: J Clin Endocrinol Metab
Volume: 91
Issue: 7
First page : 2732
Last page: 7
Number of pages: 6
ISSN: 0021-972X
DOI: https://doi.org/10.1210/jc.2005-2443
Abstract
Ultrasound determination of testis size at 0, 3, and 18 months and blood sampling (n = 727) at 3 months were analyzed.\nThe participants of the study included 633 Danish and 1044 Finnish boys, born at term with appropriate weight for gestational age.\nTestis volume was significantly higher at all ages in Finnish than in Danish boys (medians, 98 vs. 95, 185 vs. 119, and 188 vs. 136 mm(3), respectively; P < 0.00001). Testis growth from birth to 3 months was larger in Finnish than in Danish boys (mean, 75 vs. 26 mm(3); P < 0.0001). Serum hormone levels were higher in Finnish than Danish boys for inhibin B (median, 456 vs. 385 pg/ml; P < 0.0001), FSH (1.33 vs. 1.21 IU/liter; P < 0.036), and SHBG (143 vs. 136 nmol/liter; P < 0.022). Inhibin B was significantly positively correlated to testicular volume (r = 0.25; P < 0.006).\nTesticular volume and reproductive hormones were measured.\nThe larger testes and higher inhibin B levels most likely represent a bigger volume of seminiferous tubules in Finnish compared with Danish boys. Although this phenomenon may be attributable to a genetic difference between the two countries, it may also reflect environmental factors influencing testicular development.\nRecent studies showed that male reproductive health problems, such as cryptorchidism, hypospadias, testicular cancer, and low sperm quality, are more prevalent in Denmark than in Finland.\nWe hypothesized that, if fetal testicular dysgenesis contributed to these observations, differences in gonadal development and the hypothalamus-pituitary-testis axis would already be detectable perinatally. Thus, we investigated healthy newborn boys in both countries.\nThis was a prospective, longitudinal population-based study.\nTwo primary obstetric centers were included at the University Hospitals of Copenhagen, Denmark, and Turku, Finland.\nINTERVENTIONS\nPARTICIPANTS\nRESULTS\nMAIN OUTCOME MEASURES\nCONCLUSIONS\nCONTEXT\nOBJECTIVES\nDESIGN\nSETTING
Ultrasound determination of testis size at 0, 3, and 18 months and blood sampling (n = 727) at 3 months were analyzed.\nThe participants of the study included 633 Danish and 1044 Finnish boys, born at term with appropriate weight for gestational age.\nTestis volume was significantly higher at all ages in Finnish than in Danish boys (medians, 98 vs. 95, 185 vs. 119, and 188 vs. 136 mm(3), respectively; P < 0.00001). Testis growth from birth to 3 months was larger in Finnish than in Danish boys (mean, 75 vs. 26 mm(3); P < 0.0001). Serum hormone levels were higher in Finnish than Danish boys for inhibin B (median, 456 vs. 385 pg/ml; P < 0.0001), FSH (1.33 vs. 1.21 IU/liter; P < 0.036), and SHBG (143 vs. 136 nmol/liter; P < 0.022). Inhibin B was significantly positively correlated to testicular volume (r = 0.25; P < 0.006).\nTesticular volume and reproductive hormones were measured.\nThe larger testes and higher inhibin B levels most likely represent a bigger volume of seminiferous tubules in Finnish compared with Danish boys. Although this phenomenon may be attributable to a genetic difference between the two countries, it may also reflect environmental factors influencing testicular development.\nRecent studies showed that male reproductive health problems, such as cryptorchidism, hypospadias, testicular cancer, and low sperm quality, are more prevalent in Denmark than in Finland.\nWe hypothesized that, if fetal testicular dysgenesis contributed to these observations, differences in gonadal development and the hypothalamus-pituitary-testis axis would already be detectable perinatally. Thus, we investigated healthy newborn boys in both countries.\nThis was a prospective, longitudinal population-based study.\nTwo primary obstetric centers were included at the University Hospitals of Copenhagen, Denmark, and Turku, Finland.\nINTERVENTIONS\nPARTICIPANTS\nRESULTS\nMAIN OUTCOME MEASURES\nCONCLUSIONS\nCONTEXT\nOBJECTIVES\nDESIGN\nSETTING
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