The study, published in Annals of Internal Medicine, examined previous studies that provided data on 24,109 men from around the world.

Healthy testosterone levels for men can range from 300 to 1,000 nanograms per deciliter (ng/dL), with the study finding that men with testosterone levels below 153 ng/dL had a higher risk of dying from heart disease. 

The researchers found that men with less than 213 ng/dL of testosterone had a higher risk for all-cause mortality.

Low testosterone levels can cause symptoms like a lowered libido, hair loss, fatigue and mood swings.

Very low testosterone concentrations can also possibly be an indicator of other health issues, like diabetes, an infection or physical injury.  

The study’s findings suggest that testosterone levels could be an important indicator of health, and concluded that “Men with low testosterone, high LH, or very low estradiol concentrations had increased all-cause mortality.”