A variety of age related illnesses can be predicted by a single hormone that appears at a steady level in men over the course of their lives.

The INSL3 hormone first appeared during puberty. It doesn't go up in old age. INSL3 is valuable to scientists because of its consistency and early age.

A person with lower INSL3 levels at a young age is more likely to have lower levels of the hormone in old age. It's possible that the health risks could be managed many years earlier if the study is correct.

"Understanding why some people are more likely to develop disability and disease as they age is vital so that interventions can be found to ensure people not only live a long life but also a healthy life as they age."

The hormone discovery will pave the way for not only helping people individually, but also helping to ease the care crisis we face as a society.

Unlike testosterone, INSL3 doesn't change as a man becomes an adult.

In order to monitor the level of INSL3 in the blood, researchers took samples from more than 2200 men. The men's INSL3 levels varied greatly between individuals, enough to tease apart health risks.

Researchers suggest that INSL3 levels in the blood correlate to the number and health of the Leydig cells in the testes, and that having fewer of these cells and less testosterone has been linked to many health issues in later life.

"Now that we know the role this hormone plays in predicting disease and how it varies amongst men, we are turning our attention to finding out what factors have the most influence on the level of INSL3 in the blood."

"Preliminary work suggests early life nutrition may play a role, but many other factors such as genetics or exposure to some environmental disrupters may play a part."

There was a correlation between INSL3 and an increased risk of morbidity in eight of the nine morbidity categories that participants reported in questionnaires.

Most of the associations with INSL3 were lost except for high blood pressure and cardiovascular disease when the researchers adjusted for other factors.

Lower INSL3 levels in blood samples from a group of men were associated with a number of health outcomes. This was not taken into account.

The scientists want to explore how INSL3 relates to sexual health, with its strong association with testosterone, but that wasn't included in this particular piece of research.

Future studies should focus on longer time periods to determine if INSL3 measured in younger or middle aged men is indicative of later appearance of age dependent health issue.

If the link between INSL3 and these health risks is established by further studies and scientists are able to identify exactly why the link exists, preparations can be made much earlier to try and stop a variety of age related health problems.

The holy grail of aging research is to reduce the fitness gap as people get older.

The research has appeared in a journal.