Timing is key when it comes to testing testosterone levels, according to new research that finds levels of the hormone can fluctuate widely throughout the day in men younger than 45.
Doctors often recommend that men with erectile dysfunction have their testosterone tested between 8 a.m. and 11 a.m., because levels are usually highest then. But the new study found that this variation occurs only in younger men, The New York Times
Researchers studied records of 2,569 men ages 26 to 84 who were evaluated at an erectile dysfunction clinic from 1985 to 2004. They sorted them into age groups, starting with 26- to 39-year-olds, and then in five-year groups up to age 84.
The results showed the only men who had a significant decrease in levels throughout the day were those younger than 45.
Lead researcher Charles Welliver, M.D., a fellow at Southern Illinois University School of Medicine, said that the timing of the test was unimportant for most men.
“As long as the draw is done before 2 p.m.,” he said, “the value is still considered valid, except for the youngest two groups of men seen in this study.”
The analysis appeared in The Journal of Urology.