Clinical and endocrine features of hyperprolactinaemic amenorrhoea

The effect of pregnancy on suspected pituitary adenomas after conservative management of ovulation defects associated with galactorrhea

Thirty infertile patients with ovulation defects and galactorrhea conceived after medical therapy: four after clomiphene stimulation (with or without hCG) and 26 after receiving CB-154 (2-Br-alpha-ergocryptine or bromergocryptine). Pregnancies were followed closely; sellar tomography and perimetry were repeated at 36 weeks' and 8 weeks' post partum. One patient required transsphenoidal adenectomy because of acute pituitary enlargement. Two developed minimal asymptomatic fossa enlargement. Lactation was suppressed with Lactostat in the first eight patients delivered; hyperprolactinemia, amenorrhea, and galactorrhea recurred. Five of eight showed asymptomatic enlargement of the sella. Bromergocryptine was used to suppress lactation in the rest. Long-term bromergocryptine therapy resulted in the restoration of euprolactinemic ovulatory cycles in all patients. These data suggest that patients with ovulation defects associated with galactorrhea can conceive with medical therapy now available. However, there is a risk of significant pituitary enlargement during pregnancy and the puerperium. Lactation should be suppressed with bromergocryptine.

Relationship between plasma prolactin concentration and pituitary function in patients with a pituitary adenoma

The influence of hyperprolactinaemia on endocrine functions in forty-two consecutive patients with untreated pituitary tumours was studied. Patients with acromegaly, Cushing's disease and Nelson's syndrome were excluded. Sixteen patients (eleven men and five women) had a pituitary adenoma with suprasellar extension and twenty-six (eleven men and fifteen women) had a small intrasellar tumour. Basal plasma prolactin concentration was measured in all. Thyroid function was assessed by plasma thyroxine (T4) and TSH concentrations, adrenocortical function and growth hormone (GH) secretion by the maximum plasma cortisol, adrenocorticotrophin (ACTH) and GH concentrations, respectively, during insulin-induced hypoglycaemia (tITT). Gonadal function was studied by measuring plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), oestradiol-17 beta and in men, testosterone. On the basis of computer assisted tomography of the sella turcica, the tumour volume was calculated. The basal plasma prolactin concentration was elevated in 69% of the patients. Decreased GH secretion was the most frequent pituitary dysfunction (78%) followed in men by gonadal insufficiency (77%), adrenocortical insufficiency (31%) and thyroid insufficiency (21%). There was no difference between patients with elevated and normal plasma prolactin concentration as to the tumour volume and any of the endocrine variables.

Relationship between plasma prolactin and the endocrine microenvironment of the developing human antral follicle

The aim of the present study was to determine whether any obvious relationships exist between the circulating levels of prolactin at the time of ovariectomy and the endocrine microenvironment and developmental status of antral follicles. The concentrations of prolactin, follicle-stimulating hormone (FSH), and estradiol were measured in peripheral plasma and in antral fluid of follicles collected at varying stages of the menstrual cycle. In addition, the granulosa cells were recovered from each follicle (greater than or equal to 4 mm in diameter) and their numbers were quantitated. When the plasma levels of prolactin ranged from 11 to 100 ng/ml, the antral fluid levels of prolactin were uniformly low (less than 20 ng/ml) and the over-all level of intrafollicular activity remained unchanged. However, when the prolactin concentrations in plasma exceeded 100 ng/ml, the levels of prolactin in antral fluid were significantly elevated. Moreover, the high levels of intrafollicular prolactin were associated with a marked reduction in FSH accumulation and low levels of estradiol in antral fluid. Also, these follicles were severely deficient in granulosa cells. This marked reduction in intrafollicular activity was not associated with any significant changes in the mean levels of estradiol and FSH in peripheral plasma. These findings suggest that hyperprolactinemia is associated with a marked reduction in intraovarian activity and that the extent of this reduction may not be always apparent from the levels of circulating estradiol.

Tests of prolactin secretion in diagnosis of prolactinomas

Prolactin-secreting tumours of the pituitary were identified and treated by transsphenoidal microsurgery in fourteen infertile females with hyperprolactinaemia. Resting prolactin levels were 590--9000 mU/1 (mean 3400). In seven patients, tomography of the pituitary fossa was normal and resting prolactin levels were 590-6000 mU/1 (mean 3400). In these patients the pre-operative diagnosis prolactinoma in these patients was made by demonstrating loss of the normal circadian prolactin profile and impaired prolactin response to intravenous thyrotrophin-releasing hormone (T.R.H.) and metoclopramide stimulation. Prolactin response to the acute oral administration of L-dopa and bromocriptine was of less diagnostic value. Preoperative assessment of anterior pituitary function identified abnormalities other than hyperprolactinaemia in four patients (28%). Post-operative assessment indicated that microsurgery was curative in twelve patients (86%), selective in all, and without significant side-effect. It is concluded that dynamic tests such as T.R.H. and metoclopramide stimulation have considerable value in identifying hyperprolactinaemic patients with prolactin-secreting adenomas, particularly those which are radiologically occult.

Oestrogen modulation of gonadotrophin and prolactin release in women with anovulation and their responses to clomiphene

An LHRH test was performed before and at both 44 and 92 h after the administration of 2.5 mg oestradiol benzoate in eleven patients with hyperprolactinaemia, eight with idiopathic secondary amenorrhoea and seven with oligomenorrhoea. The basal serum hormone concentrations and the responses to LHRH were compared with the same tests performed on ten normal subjects during the early follicular phase of their menstrual cycles (days 4--6). Mean basal concentrations of oestradiol in each group of patients and oestrone in those with hyperprolactinaemia were significantly lower than in the normal subjects. The mean concentration of prolactin in women with secondary amenorrhoea remained lower than in the normal women throught the tests (P less than 0.05). The LH and FSH responses to LHRH before oestrogen in patients with hyperprolactinaemia and of FSH in those with secondary amenorrhoea, were greater than in the normal subjects (P less than 0.001). After oestrogen treatment the responses were similar in all groups except in those with oligomenorrhoea where LH and FSH responses at 44 h (P less than 0.05 and P less than 0.01 respectively) and LH responses at 92 h (P less than 0.01) were lower than in normal controls. The responses at 92 h in all groups were greater than at 44 h (amplification) but the amplification at 92 h and at 44 h compared to the pre-treatment responses, tended to be lower in each group of patients compared to the normal controls. In the hyperprolactinaemic group of patients there was a negative correlation between the basal prolactin concentration and the gonadotrophin amplifications at 92 h (P less than 0.01), and a positive correlation between the basal oestrone levels and the amplifications at 92 h (P less than 0.01). The results of the oestrogen amplification test in eleven of the non-hyperprolactinaemic anovular patients were compared with the ovulatory response to 100 mg clomiphene given for 5 days. Six showed a normal oestrogen amplification and they all ovulated. Two patients failed to show greater amplification at 92 than at 44 h and required human chorionic gonadotrophin (HCG) as well as clomiphene to ovulate. The other three showed a diminished LH amplification at 92 h; they required 200 mg clomiphene and showed a prolonged follicular phase. The responses of the hyperprolactinaemic patients to clomiphene were poor and there was a negative correlation between prolactin concentration and oestrogen production (P less than 0.01). All ten hyperprolactinaemic patients treated with bromocriptine ovulated and eight conceived. The oestrogen amplification test appears to have some value in predicting the subsequent response to clomiphene in non-hyperprolactinaemic anovular women.

Pituitary microadenoma: diagnostic studies

Forty-one women with oligo-menorrhoea and/or galactorrhoea were subjected to hypothalamic pituitary-thyroid testing in an attempt to establish the presence or absence of an underlying pituitary microadenoma. They were divided into two groups in accordance with the serum level of prolactin (PRL): Group I (N = 25, mean +/- SE 17.6 +/- 1.5 ng/ml) and Group II (N = 16, 102.8 +/- 29.7 ng/ml). The dynamic tests performed were a TRH test, a stimulation test with metoclopramide (MCP) and a suppression test with bromocriptine. The results of these tests were compared with those obtained in nine normal women and eleven patients with surgically proved pituitary microadenoma. Radiologically abnormal pituitary fossas were found in ten subjects from Group I and in fourteen from Group II. All patients were euthyroid. A persistently elevated serum TSH in response to TRH was observed in patients of Group II suggesting an hypothalamic abnormality and a progressive decrease in the 120-min use of serum T3 was noted with increasing evidence of the existence of a pituitary tumour. A negative correlation was found between the basal serum PRL and the rise of serum PRL with TRH. Patients from Group II showed a lower PRL response to MCP when compared to Group I and again a negative correlation between basal level of serum PRL and the change after MCP was observed. No clear difference in the 4-h response to bromocriptine was found between the different groups of subjects. In conclusion, none of the three tests analysed permitted us to establish which of the patients had an underlying pituitary microadenoma.

Assessment of pituitary function

Sellar and parasellar tumours comprise 10-15% of all intracranial neoplasms. Neurologists will this often be faced with the problem of assessing pituitary function. A thorough clinical examination is of the foremost importance. In addition a small number of simple and rapid tests is required. Knowledge of the physiological variation in pituitary function is, however, necessary to allow a safe interpretation of the results. A simple routine procedure for assessing pituitary function is proposed.

Bromocriptine treatment of seven women with primary amenorrhoea and prolactin-secreting pituitary tumours

Seven women with primary amenorrhoea and hyperprolactinaemia were treated with bromocriptine. All the women had started to develop secondary sex characteristics at normal age but pubertal development stopped and menarche did not occur. Radiological signs of a pituitary tumour were found in all the women. Before the pituitary tumour was diagnosed, four women had been given longterm cyclical oestrogen replacement therapy. Three women had received primary tumour therapy with surgery and/or irradiation but had persistent hyperprolactinaemia. The basal luteinizing hormone (LH) levels were low in four of the women while all the women had normal basal levels of follicle-stimulating hormone (FSH) and normal or exaggerated gonadotrophin responses to luteinizing hormone-releasing hormone (LHRH). None of the women had evidence of endogenous oestrogen production before treatment. Bromocriptine treatment normalized the raised serum prolactin levels (46-2900 microgram/l) in all but one woman, in whom the prolactin level decreased from 160 to 38 microgram/l. Regular ovulatory menstrual cycles appeared in four women, one of whom had previously been treated by transsphenoidal adenomectomy followed by external irradiation. Two other women with persistent hyperprolactinaemia after previous surgical and/or irradiation treatment of large pituitary tumours did not menstruate after more than one year of treatment with bromocriptine. One infertile patient with a microadenoma conceived at the first ovulation on therapy and developed symptoms and signs of tumour growth during pregnancy.

The diagnostic value of pharmacodynamic tests in the hyperprolactinaemic syndrome

Patterns of prolactin (PRL) secretion were studied in a group of 18 hyperprolactinaemic patients with galactorrhoea and menstrual disorders and in a control group of thirty-two women in the early puerperium (24 h after a normal delivery) following provocative (TRH and Chlorpromazine) and suppressive (L-Dopa and bromocriptine) stimuli. Five out of the eighteen hyperprolactinaemic patients tested had radiological evidence of a pituitary tumour, and two were treated surgically. The early puerperium patients with elevated basal PRL levels (100--700 ng/ml) demonstrated a significant PRL response to the various treatments. On the other hand, in the hyperprolactinaemic group, an impaired PRL response to TRH, Chlorpromazine and L-Dopa was noted in patients with basal PRL levels higher than 30 ng/ml, whereas bromocriptine suppressed effectively PRL levels in all the hyperprolactinaemic patients tested irrespective of their basal PRL concentrations. The ratio between the fall in PRL concentrations (as percent of the baseline) after L-Dopa administration (delta%L) versus the PRL decrement after bromocriptine treatment (delta%B) was calculated. In the early puerperium group with normal pituitary prolactin secreting cells this ratio was equal to 0.8. In the hyperprolactinaemic group, the five patients with radiological evidence of a pituitary tumour had significantly lower ratios ranging from 0.2 to 0.57. These data suggest that in terms of prolactin release, prolactin producing tumour cells are intrinsically refractory to hypo thalamic dopaminergic signals. The calculation of individual delta%L/delta%B ratios may serve, therefore, as a valuable indicator for early detection of autonomous pituitary prolactin secreting cells and for evaluation of the extent of the pituitary lesion.

Serum-prolactin in female infertility

55 of 100 new female patients attending an infertility clinic had serum-prolactin concentrations greater than the upper limit of normal (360 mU/l). There was no significant correlation between serum-prolactin value and clinical features including age, duration of infertility, past reproduction, menstrual pattern, past use of oral contraception, or pregnancy-rate after treatment. The place of serum-prolactin estimations in the management of infertile women is unclear, particularly since the precision of currently available radioimmunoassays is questionable. The major value of serum-prolactin estimations lies in identifying those patients in whom further investigation for pituitary tumour is indicated both before treatment and during any ensuing pregnancy, and in selecting patients suitable for bromocriptine therapy.

Diagnosis of hyperprolactinaemia

The significance of hyperprolactinaemia is poorly understood by many clinicians. Difficulties in interpretation have arisen because many endogenous factors can alter prolactin secretion, the scale of laboratory errors is not appreciated, and reference ranges are inappropriately used. There is a need for improved communication between clinician and laboratory and for education on both sides.

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.

Pituitary tumors and pregnancy

This paper contains a review of the natural history of pituitary tumors in nonpregnant and pregnant patients. Data were drawn from previously published reports and from responses to a questionnaire and were analyzed by life-table techniques. Follow-up of 62 nonpregnant patients with untreated pituitary tumors with and without visual field changes revealed a median time to treatment of 15 1/2 years and similar, relatively constant hazard functions. In 91 pregnancies occurring in 73 women with previously untreated pituitary tumors, ovulation had occurred spontaneously in 9 per cent, headache occurred in 23 per cent, and visual disturbances in 25 per cent with 61 per cent remaining asymptomatic. In those patients who developed symptoms, median time to headache was 10 weeks and to visual disturbance, 14 weeks. The hazard functions were relatively constant and similar. The relative risk of developing symptoms is independent of whether or not the first or second pregnancy occurred in the presence of the pituitary tumor. Of the pregnant patients with previously untreated pituitary tumors, 30 per cent required surgery or radiation therapy. Median time to treatment was 19 weeks. None of the 69 pregnant women without pituitary therapy had permanent sequelae. Only four patients who underwent surgery or received radiation treatment developed permanent symptoms and none was serious. In 78 pregnancies occurring in 73 women with previously treated pituitary tumors, headache occurred in 4 per cent and visual disturbances in 5 per cent. Only one patient required therapy. Treatment during pregnancy results in significantly increased prematurity rates but unchanged abortion and perinatal mortality rates. Small pituitary tumors do not constitute a contraindication to either induction of ovulation or pregnancy.

Hormonal correlates of normal and abnormal follicle growth after puberty in humans and other primates

After the menarche, changing levels of gonadotrophins, prolactin and sex steroid hormones in peripheral blood are accompanied by ovulation and corpus luteum formation in one follicle, and atresia in the remaining follicles maturing during each menstrual cycle. Available evidence suggests that blood levels of steroid hormones reflect in large part the secretory activity of the ovary containing a pre-ovulatory follicle and most probably of that follicle itself (see Chapter 6). These steroid secretions and those of the corpus luteum coordinate hypothalamic-pituitary-ovarian function. Within the ovary, sex steroid hormones mediate effects of gonadotrophins and prolactin on follicle maturation and participate in determining the fate of individual follicles.

Failure of withdrawal bleeding during combined oral contraceptive therapy: "amenorrhoea on the pill"

Serum follicle stimulating hormone, luteinising hormone and oestradiol-17beta concentrations have been measured in 21 patients with failure of withdrawal bleeding during combined oral contraceptive therapy and 21 matched controls with a normal bleeding pattern. Gonadotrophin and oestradiol-17beta concentrations were effectively suppressed in all patients during the phase of contraceptive ingestion. During the week between courses of treatment, there was a significant rise in the gonadotrophin (p less than 0.02) and oestradiol (p less than 0.05) concentrations in the patients but not in the controls. It is suggested that patients with failure of withdrawal bleeding during combined oral contraceptive therapy may have higher total oestrogen levels during the treatment-free week because of a less persistent suppression of hypothalamic-pituitary-ovarian function.

The effect of varying prolactin levels on pituitary luteinizing hormone and follicle-stimulating hormone response to gonadotropin-releasing hormone

Seventy-one women with menstrual irregularities were investigated by measurement of basal plasma estradiol, prolactin, and gonadotropin levels. They were each given an intravenous injection of 100 microgram of gonadotropin-releasing hormone (GnRH), and both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured for two hours. The women were divided into three groups on the basis of the prolactin levels: "normal," "mild elevation," and "severe elevation." For each prolactin group there was no difference in age or estradiol or basal LH and FSH levels. The pituitary response to the GnRH injection was also similar for the three groups. These data suggest that elevated prolactin levels do not interfere with pituitary gonadotropin cell function.

A case of multiple endocrine adenomatosis with primary amenorrhoea

A well documented sporadic case of multiple endocrine adenomatosis (MEA) type I, with the pituitary tumour presenting as a prolactinoma, is described in a 28-year-old female. Primary amenorrhoea, resulting from hyperprolactinaemia, was the first symptom of the polyglandular neoplasia. A gastrinoma was removed from the head of the pancreas and latent hyperparathyroidism appeared to be present. Treatment with bromocriptine was poorly tolerated; neurosurgical intervention was refused by the patient. The possibility that a serum prolactin determination may be useful in detecting pituitary involvement in MEA deserves consideration.

Intrauterine development, feto-placental function and pregnancy outcome after induction of ovulation with bromoergocryptine

18 pregnancies occurred after treatment with bromoergocryptine in 17 patients who wished to conceive, but who suffered from anovulation of varying aetiology. The course of 15 pregnancies was uneventful. Three pregnancies ended in abortion. Nine of the 17 women had hyperprolactinemic amenorrhea. Furthermore, one woman had normoprolactinemic post-pill amenorrhea, another normoprolactinemic anovulatory oligomenorrhea and a third normoprolactinemic anovulatory regular menstruations. With the exception of one woman, all had galactorrhea. The courses of pregnancy were monitored by frequent ultrasound measurements of the fetal biparietal diameter, maternal urinary estriol excretion and radioimmunological measurements of plasma estrone, estradiol, unconjugated and immunoreactive estriol, progesterone, and HPL. All data were within the normal ranges and all babies were healthy at birth and had no teratogenic defects. The data prove the great value of bromoergocryptine in the treatment of hyperprolactinemic anovulation, sometimes even in the treatment of normoprolactinemic anovulation. Moreover, the results indicate no adverse effect on either the course or the outcome of pregnancy.

Clinical course and outcome of pregnancies in amenorrhoeic women with hyperprolactinaemia and pituitary tumors

Seventeen term pregnancies occurred in 14 amenorrhoeic women with hyperprolactinaemia and radiological evidence of pituitary tumour. The abortion rate was high (32%). All but one of the term pregnancies occurred after ovulation-inducing treatment with human gonadotrophins and bromocriptine (four and 12 pregnancies respectively). Two of the 14 women had visual complications during pregnancy, but neither had serious residual visual impairment. Two patients had possible pituitary enlargement during pregnancy.Bromocriptine may be the most suitable primary treatment for many infertile women with prolactin-secreting tumours. Tumour complications during pregnancy are a definite risk, but most pregnancies went uneventfully to term. Patients with pituitary tumour should be carefully evaluated before starting ovulation-inducing treatment with bromocriptine alone, and they should be told of the possible risks and of the advantages and disadvantages of pretreatment with irradiation or surgery. Patients should be carefully monitored during pregnancy and have their visual fields checked frequently. If visual complications due to tumour enlargement occur during a pregnancy, reinstituting bromocriptine may be the treatment of choice. If this fails, other forms of treatment such as induction of labour, high-dose corticosteroid treatment, pituitary implantation of yttrium-90, or surgery may be effective.

Hyperprolactinaemia and impotence

Clinical, laboratory and radiological findings were evaluated in twenty-nine men who had raised serum prolactin concentrations and pituitary tumours. Twenty-one had functionless pituitary tumours ('prolactinomas') and eight had acromegaly. Supraseller extension was detected in twenty of the twenty-six men who had lumbar airencephalography. Three patients were studied before, sixteen before and after and ten only after pituitary ablative therapy. Seventeen of these men complained of complete lack of libido and impotence and six had impaired libido and sexual potency; only six patients in this series denied reproductive symptoms. Thirteen of the impotent subjects had small soft testes, ten reduced facial and body hair and three had marked gynaecomastia. No features of hypogonadism were noted in the six patients without reproductive symptoms and none of the patients had galactorrhoea. Serum prolactin concentrations were higher and serum testosterone concentrations lower in the impotent men compared with those with normal sexual potency. Serum LH and FSH (both basal and in response to LHRH) oestradiol and oestrone concentrations were not different between the two groups and, except in those with post-operative hypopituitarism, were within the normal range. Following successful lowering of prolactin concentrations by surgery or bromocripitine or both, serum testosterone rose and potency returned; by contrast failure to lower prolactin concentrations was associated with persistent impotence and hypogonadism. The endocrine profile of low serum testosterone concentrations with gonadotrophins which had not risen into the range usually seen in primary hypogonadism (together with the parallel increase of LH and testosterone in one patient studied sequentially during treatment which suppressed prolactin levels to normal), suggested that the impaired gonadal function was caused by a prolactin-mediated disturbance of hypothalamic-pituitary function.

Management of hyperprolactinaemic amenorrhoea

Results of treatment of 52 patients with amenorrhoea associated with hyperprolactinaemia are presented. All patients had a detailed radiological examination of the pituitary fossa, including lateral tomography in every patient and air encephalography in those in whom a pituitary tumour was suspected. There were 17 patients with untreated pituitary tumours, 5 patients with previously treated pituitary tumours and persisting hyperprolactinaemia, and 30 patients with normal pituitary radiology. Patients with pituitary tumours were treated either by transsphenoidal or transfrontal surgical extirpation of the tumour, followed, if necessary, by external irradiation and/or bromocriptine, Four patients were treated with external irradiation as primary therapy, and three patients who did not wish to conceive were treated with bromocriptine as primary therapy. Patients with normal radiological appearances were treated with bromocriptine as primary treatment. Ovulatory menstrual cycles developed in 42 patients and there were 19 pregnancies. Those ovulating but not conceiving had adequate nonendocrine factors to account for the disparity. Failure of response was seen in 10 patients and was due to inadequate fall of prolactin in response to surgery (2 patients), external irradiation (3 patients) and bromocriptine (1 patient), and gonadotrophin deficiency which developed after surgery in 3 patients but was present pre-operatively in 1. The relative merits of treatment by surgery, external irradiation and bromocriptine are discussed and a policy of treatment outlined.

The control of gonadotrophin release in women with hyperprolactinaemic amenorrhoea: effect of oestrogen and progesterone on the LH and FSH response to LHRH

The effect of the administration of oestradiol benzoate and of progesterone on the subsequent response to LHRH has been investigated in women with hyperprolactinaemia. There was an amplification in the release of LH in four out of ten patients and of FSH in one out of ten patients at 44 h after the administration of 2-5 mg oestradiol benzoate. The average amount of LH released before and after oestrogen did not change, but there was a significant decrease in the amount of FSH released. There was no correlation between the LH released and the oestradiol concentration in serum at the time of the LHRH tests but there was a negative correlation between the FSH released and the oestradiol concentration (r = 0-507;P less than 0-05). These results contrast with those obtained in normal subjects in the follicular phase of the cycle when there is a positive correlation of oestrogen concentrations and the amount of LH and FSH released. As in normal subjects, however, a significant suppression of basal FSH concentrations, persisting until 44 h, was produced by the oestrogen (P less than 0-01). Seven out of eleven patients showed an amplification of LH response and six out of eleven an FSH response 20 h after the administration of 25 mg progesterone. The mean amplifications are not significantly different from those of normal subjects tested in the early follicular phase of the cycle, but are significantly less than those tested in the mid follicular phase of the cycle (LH P less than 0-001; FSH P less than 0-01). This may be related to the serum concentrations of oestradiol which in patients with hyperprolactinaemia are significantly less than those found in the mid follicular phase of the cycle (P less than 0-05). These results indicate that in women with hyperprolactinaemia oestrogen negative feedback, necessary for cycle initiation, is normal: failure of ovulation may be related to failure of positive feedback to oestroen. Oestrogen-negative feedback is unopposed and this may explain the follicullar development and lack of oestrogen in the mid-follicular phase.