Men with low sperm count are more likely to have a number of health issues that put them at increased risk of illness, a study has found.
The research on 5,177 men in Italy evaluated semen quality, reproductive function and metabolic risk in males referred for fertility evaluation.
"Our study clearly shows that low sperm count by itself is associated with metabolic alterations, cardiovascular risk and low bone mass," said Alberto Ferlin, who carried the study at University of Padova in Italy.
"Infertile men are likely to have important co-existing health problems or risk factors that can impair quality of life and shorten their lives," said Ferlin, now an associate professor at University of Brescia in Italy.
"Fertility evaluation gives men the unique opportunity for health assessment and disease prevention," he said.
In the study, about half the men had low sperm counts and were 1.2 times more likely than those with normal sperm counts to have greater body fat (bigger waistline and higher body mass index, or BMI).
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They were also more likely to have higher blood pressure, "bad" (LDL) cholesterol and triglycerides, and lower "good" (HDL) cholesterol.
They also had a higher frequency of metabolic syndrome, a cluster of these and other metabolic risk factors that increase the chance of developing diabetes, heart disease and stroke, the researchers said.
A measure of insulin resistance, another problem that can lead to diabetes, also was higher in men with low sperm counts, they said.
Low sperm count was defined as less than 39 million per ejaculate.
The researchers found a 12-fold increased risk of hypogonadism, or low testosterone levels, in men with low sperm counts.
Half the men with low testosterone had osteoporosis or low bone mass, a possible precursor to osteoporosis, as found on a bone density scan.
These findings, according to Ferlin, suggest that low sperm count of itself is associated with poorer measures of cardiometabolic health but that hypogonadism is mainly involved in this association.
He cautioned that their study does not prove that low sperm counts cause metabolic derangements, but rather that sperm quality is a mirror of the general male health.