Serum prolactin and gonadotrophin levels before and after luteinizing hormone-releasing hormone in the investigation of amenorrhoea.

An intravenous luteinizing hormone-releasing hormone (LRH) test was performed in 287 women with amenorrhoea. Prolactin, progesterone and oestrogens in serum were also measured. Twenty-four women with premature ovarian failure and 9 with gonadal dysgenesis had raised basal follicle-stimulating hormone (FSH) levels. Neither the basal luteinizing hormone (LH) level nor the gonadotrophin responses after LRH gave a better separation of this group of women with irreversible ovarian failure. Measurement of prolactin levels were valuable in that 15 of 42 patients with hyperprolactinaemia had a radiologically abnormal pituitary fossa, whereas pituitary fossa abnormalities were found in only 11 of 245 normoprolactinaemic women. It was thought that 181 women had functional amenorrhoea; 54 per cent of these women had developed amenorrhoea in relation to weight loss and 32 per cent in relation to discontinuation of oral contraceptives. A strong correlation was found between the body weight and the basal gonadotrophin levels. The basal LH levels were correlated with serum oestrogen levels, the basal FSH level and the LH response to LRH. Most of the patients with low basal LH values had developed amenorrhoea in relation to self-imposed weight-loss. The responses to LRH were often impaired in the underweight patients but became normal after weight gain. The polycystic ovary syndrome (PCO) could not be diagnosed by measuring either basal or LRH-stimulated gonatrophin levels. Single FSH and prolactin determinations in serum seemed to be the only indispensible hormone assays in the routine clinical evaluation of amenorrhoea.