Scientists have identified symptoms of male menopause but they say this impacts just two percent of elderly men unlike the female menopause that affects all women.

Male menopause is relatively rare and is linked to poor health and obesity. The findings should provide new insights to physicians prescribing male testosterone therapy.

The researchers from University of Manchester, Imperial College London, University College London and other European partners measured the testosterone levels of 3,369 men between the age of 40 and 79 years. Details were sought about their sexual, physical and psychological health.

The team found that only nine of the 32 symptoms were actually associated with low testosterone levels, the most important being the three sexual symptoms - decreased frequency of morning erection, decreased frequency of sexual thoughts (sex drive), and erectile dysfunction.

The study concluded that the presence of all three sexual symptoms, together with low testosterone levels was required to establish a diagnosis of late-onset hypogonadis (male menopause), although other non-sexual symptoms may also be present.

Other symptoms included three physical symptoms - inability to engage in vigorous activity such as running or lifting heavy objects, inability to walk more than one kilometre, and inability to bend, kneel or stoop.

Psychological symptoms included, loss of energy, sadness and fatigue. But non-sexual symptoms were only weakly related to low testosterone.

Additional symptoms, often associated with the male menopause were discounted as not being testosterone related. These includeed changes in sleeping pattern, poor concentration, feeling worthless, nervousness or anxiety and difficulty getting up from a chair.