<prompt> Most common cause of secondary amenorrhoea-PCODPregnancyHypothyroidismHyperprolactinemia.  <response>: Ans-B i.e., Pregnancy Secondary amenorrhoea o The absence of menstruation for 3 normal cycles or for 6 months or more in a woman with previous norma menstrual pattern in the absence of pregnancy and lactation. o Pregnancy is the most common cause of secondary amenorrhoea. The causes can be classified as follows: Physiological o Pregnancy o Lactation Pathological o Genital tract Acquired obstruction gynatresia of cervical Ashermans syndrome following excessive curettage, uterine infection or endometrial tuberculosis, transcervical resection of endometrium for dysfunctional uterine bleeding DUB. Vesicovaginal fistula-cause unknown. o Ovarian causes Surgical extirpation. Radiotherapy. Autoimmune disease. Induction of multiple ovulation in infertility-leading to premature menopause. Polycystic ovarian disease PCOD. Resistant ovarian syndrome-due to absent FSH receptors. Infections-mumps, tuberculosis, rarely pyogenic infections. Masculinizing ovarian tumours. Premature menopause. o Nutritional causes Anorexia nervosa, bulimia. Extreme obesity. Excessive weight loss in athletes and ballet dancers. o Pituitary causes Insufficiency as in Simmonds disease, Sheehans syndrome. Hyperprolactinaemia. Tumours like prolactinomas and chromophobe adenomas, and Cushings disease. Empty sella syndrome. Drugs-tranquillizers, oral contraceptive OC pills, metoclopramide, dopamine blockers, antihypertensives, antidepressants, cimetidine and phenothiazine. o Hypothalamus GnRH deficiency. Vigorous exercise. Pseudocyesis. Brain tumours. Anorexia nervosa. o Suprarenal causes Addisons disease. Adrenogenital syndrome. Suprarenal tumours. o Thyroid Hypothyroidism, chest wall lesions. Graves disease. o Other causes Diabetes. Tuberculosis-liver disease. Renal disease-due to reduced excretion of LH and prolactin. Severe anaemia, malnutrition. 