A man’s sperm count is a marker of his general health, according to the largest study to date evaluating semen quality, reproductive function, and metabolic risk in men 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 the study’s lead investigator, Dr Alberto Ferlin.

Ferlin, with Dr Carlo Foresto, tested semen samples of 5,177 male partners of infertile couples from Italy and found about half had low sperm counts. These men were 1.2 times more likely than those with normal sperm counts to have greater body fat, higher blood pressure, higher  levels of “bad” (LDL) cholesterol and triglycerides, and lower levels of “good” (HDL) cholesterol. The men with low sperm counts also had a higher frequency of metabolic syndrome, a cluster of conditions that increase the chance of developing diabetes, insulin resistance, heart disease and stroke, the team discovered.

Low sperm count was defined as less than 39 million per ejaculate, a value also used in the U.S. All the men in the study had a sperm analysis as part of a comprehensive health evaluation in University of Padova’s fertility clinic, which included measurement of their reproductive hormones and metabolic parameters.

The researchers found a 12-fold increased risk of low testosterone, or ‘low T,’ levels in men with low sperm counts, which suggests this condition is the link between low sperm count and poorer measures of cardiometabolic health. He cautioned that their study does not prove that low sperm counts cause metabolic derangements, but rather that sperm quality is a mirror of general male health.

The bottom line, Ferlin stressed, is that treatment of male infertility should not focus only on having a child when diagnostic testing finds other health risks, such as obesity or overweight, high cholesterol or high blood pressure.

“Fertility evaluation gives men the unique opportunity for health assessment and disease prevention,” Ferlin said. “Men of couples having difficulties achieving pregnancy should be correctly diagnosed and followed up by their fertility specialists and primary care doctor because they could have an increased chance of morbidity and mortality.”