Men with low testosterone levels may be more prone to severe Covid-19 infection, say researchers, including one of Indian origin.
The study did not find a direct correlation however, those with the lowest levels of testosterone in the blood were at the highest risk of going on a ventilator, needing intensive care or dying.
"If a man had low testosterone when he first came to the hospital, his risk of having severe Covid-19 -- meaning his risk of requiring intensive care or dying -- was much higher compared with men who had more circulating testosterone," said researcher Abhinav Diwan from Washington University School of Medicine.
"And if testosterone levels dropped further during hospitalisation, the risk increased," Diwan added.
For the study, published in the journal JAMA Network Open, the researchers measured several hormones in blood samples from 90 men and 62 women with symptoms of Covid-19 and who had confirmed cases of the illness.
For the 143 patients who were admitted to the hospital, the researchers measured hormone levels again at days 3, 7, 14 and 28, as long as the patients remained hospitalized over these time frames.
In addition to testosterone, the team measured levels of estradiol, a form of estrogen produced by the body, and IGF-1, an important growth hormone that is similar to insulin and plays a role in maintaining muscle mass.
Among women, the researchers found no correlation between levels of any hormone and disease severity. Among men, only testosterone levels were linked to Covid-19 severity.
A blood testosterone level of 250 nanograms per deciliter or less is considered low testosterone in adult men.
At hospital admission, men with severe Covid-19 had average testosterone levels of 53 nanograms per deciliter; men with less severe disease had average levels of 151 nanograms per deciliter.
By day three, the average testosterone level of the most severely ill men was only 19 nanograms per deciliter.
In addition, the team found that lower testosterone levels in men also correlated with higher levels of inflammation and an increase in the activation of genes that allow the body to carry out the functions of circulating sex hormones inside the cells.