NEW ORLEANS — Here's one more reason to advise overweight men to shed pounds: Obese men have serum markers of compromised fertility, and men who have fathered children tend to have lower body mass indexes than do those without children.
It's long been established that excess weight can impair female fertility. But a study presented in a poster session at the annual meeting of the Endocrine Society indicates that increasing body mass index (BMI) in males is associated with decreased testosterone and inhibin B levels.
“Lower inhibin B levels are indicative of dysfunction in the seminiferous tubules,” said Eric Pauli, M.D., of the Pennsylvania State University, Hershey. “Our findings indicate that these lower serum inhibin B levels point to decreased tubule function, and that inhibin B might even be a more sensitive way of detecting compromised fertility in men than a semen analysis,” he said.
Dr. Pauli analyzed semen and serum fertility markers in 87 men aged 19–48 years whose BMIs ranged from 16 to 47 kg/m
In addition to providing blood and semen samples, the men had their skinfold thickness measured and underwent testicular examinations to document testicular volume and rule out undiagnosed disease. They also answered questions about paternity status, history of infertility in self or partner, and alcohol and tobacco use.
Blood was tested for inhibin B, FSH, luteinizing hormone, testosterone, and free testosterone. Semen was examined for motility, volume, and concentration.
Almost 70% of the men had a history of paternity; they had lower BMIs (26 kg/m
Patients whose BMIs were around 42.5 kg/m
Men with BMIs of about 42.5 kg/m
There was no association of body fat with luteinizing hormone or with any semen analysis factor. However, lower inhibin B levels were associated with lower sperm motility. Free testosterone was not associated with body fat.
“These guys seem to make normal amounts of sperm, because their sperm count and sperm motility are not different from normal-weight men,” Dr. Pauli said. “However, their inhibin B, which is a marker for normal sperm cell production, is lower, suggesting that their testes make sperm that is in some way dysfunctional. We don't know the nature of this dysfunction, yet.”