Menopause happens around the age of mid 40 to mid 50. It is natural. Though nowadays, menopause is also increasingly seen in women of younger age (premature menopause). If woman does not get her period till a year it is assumed that she has achieved menopause.
Technically a woman is said to be menopausal if she has not menstruated for last consecutive twelve months, provided she is neither pregnant nor lactating.
There are no specific tests to diagnose menopause. But to diagnose any problem during menopause there are various tests depending on conditions. However in rare cases blood estradiol, Folliculating stimulating hormone, thyroid hormone level test, urine tests may be required to rule out any medical condition that is similar to menopause.