Periods, absent - Diagnosis 

You should see your GP if any of the below apply.

• you are 14 or older, have not started your periods and have not started physical sexual development, such as breast growth or pubic hair (read more about sexual development you would expect to see in a girl going through puberty) 
• you are 16 or older and have not started your periods but have normal physical features of puberty (primary amenorrhoea)
• you used to have periods but have not had one for the last six consecutive months (secondary amenorrhoea)

Your GP will determine whether you have primary amenorrhoea (a failure to start your periods) or secondary amenorrhoea (periods that have stopped). They will then try to identify the cause of your absent periods.

First, you may be offered a pregnancy test to rule out pregnancy.

Your GP will also take full details, including noting your medical history, work and activity, family medical history, sexual history and any emotional upsets or changes in body weight. They will also assess whether you are going through the normal physical stages of puberty.

• If your GP diagnoses primary amenorrhoea, you may be referred to a gynaecologist (a specialist in treating conditions that can affect the female reproductive system).
• If your GP diagnoses secondary amenorrhoea, they can usually identify the underlying cause and treat it. In some cases, they may refer you to a gynaecologist or endocrinologist (a specialist in treating hormonal conditions).

Referral: primary amenorrhoea

Your GP may diagnose primary amenorrhoea and refer you to a gynaecologist if:

• you have not started your periods by the age of 14 and your body shows no signs of going through puberty or
• you have normal features of puberty but have not started your periods by the age of 16

Your specialist may give you a full gynaecological examination and carry out various tests, which include:

• blood tests to determine your levels of prolactin, thyroid-stimulating hormone, follicle-stimulating hormone and luteinising hormone (abnormal amounts of these may be the cause of your missing periods)
• a pelvic ultrasonography, computerised tomography (CT) scan or MRI scan. These scans take detailed pictures of the inside of your body and reveal any problems with your vagina or womb

Referral: secondary amenorrhoea

Your GP may diagnose secondary amenorrhoea and refer you to a gynaecologist or endocrinologist if:

• the cause cannot be identified
• the cause needs to be confirmed
• specialist treatment is needed, for example, for infertility

Possible causes that need confirmation are:

• ovarian failure (a disorder of the ovary)
• polycystic ovary syndrome (PCOS)
• an underactive or overactive thyroid gland
• infertility
• hyperprolactinaemia (high levels of a hormone called prolactin in the blood)
• an increased level of blood testosterone that is not caused by PCOS

You may be referred to a dietitian if you are underweight (a body mass index of less than 19), or a psychiatrist or psychologist if your GP thinks you have an eating disorder.