Exercise-Induced Amenorrhoea

Exercise induced amenorrhoea is absence of menstruation in women who undertake intense physical training, caused by low energy availability (energy intake below 30 kcal/kg of fat free mass daily) that suppresses the hypothalamic pituitary ovarian axis. It occurs in athletes, runners, gymnasts, dancers and military recruits. It matters because it causes bone loss, stress fractures, infertility and cardiovascular risk, and it is part of the female athlete triad of low energy availability, menstrual dysfunction and low bone density.

• Risk factors: endurance and weight sensitive sports (running, gymnastics, ballet), high weekly training volume, restrictive eating, low body fat, adolescence, early start of training before menarche.
• Often accompanied by unintentional undereating.
• Return of menses occurs with reduced training and added energy intake.

Women have absent or infrequent periods, fatigue, poor performance, frequent injuries, stress fractures, cold intolerance, low mood and sometimes disordered eating. Examination shows low body weight or normal weight, low blood pressure and slow pulse.

• Body mass index often 18 to 20 kg/m2 or lower.
• Stress fracture pain in the foot, tibia or hip.
• Differential diagnosis: pregnancy, polycystic ovary syndrome, hyperprolactinaemia, thyroid disease, premature ovarian insufficiency, anorexia nervosa, coeliac disease, hypothalamic amenorrhoea from other causes, pituitary tumour, anabolic steroid use.
• Complications: low bone density and stress fractures, infertility, cardiovascular risk, eating disorder, depression, early osteoporosis.

The approach is to exclude other causes and measure bone health.

• Urine or serum hCG; follicle stimulating hormone, luteinising hormone, oestradiol (low), prolactin, thyroid stimulating hormone, testosterone.
• Full blood count, ferritin, electrolytes, urea, glucose, coeliac antibodies; 25-hydroxyvitamin D.
• Bone density scan (DXA) after 6 months of amenorrhoea or with a stress fracture; X-ray or MRI of painful bones.
• ECG for slow pulse or electrolyte disturbance; screening for eating disorder.

The principle is to increase energy availability and reduce training load, with bone protection and sports nutrition support.

• Supportive: reduce training volume by 10 to 20 percent and add rest days; increase energy intake by 300 to 600 kcal daily, with adequate carbohydrate and protein; target body mass index of 20 kg/m2 or more; dietitian and sports medicine review; calcium 1000 to 1300 mg and vitamin D 800 to 1000 IU oral daily; cognitive behavioural therapy for stress and body image; stop use of laxatives, diuretics or diet pills.
• Pharmacological: if amenorrhoea lasts more than 6 to 12 months, bone density Z score is below -1.0, or there is a stress fracture despite nutrition changes: transdermal oestradiol 100 micrograms/24 hours patch changed twice weekly with medroxyprogesterone 10 mg oral once daily for 12 days each month (or oestradiol valerate 2 mg oral once daily with medroxyprogesterone 10 mg oral once daily for 12 days each month); the combined oral contraceptive pill does not restore bone density and is used for contraception only; ferrous sulphate 200 mg oral 12-hourly for 3 months for iron deficiency; vitamin D3 2000 IU oral once daily for 8 to 12 weeks if the level is below 50 nmol/L.
• Procedures: none.
• Special groups: adolescents and young athletes need a longer period of reduced training with sports and endocrine review; athletes with stress fractures rest from impact exercise until healed; women with an eating disorder, pulse below 40 per minute or electrolyte disturbance need admission and psychiatric care.
• Red flags: stress fracture, body mass index below 16 kg/m2, bradycardia, syncope, low potassium or phosphate, suicidal thoughts, signs of an eating disorder.
• Follow-up: review monthly to monitor weight and training; menses usually return within 3 to 12 months of improved energy balance; bone density scan every 1 to 2 years; counselling on contraception and fertility.