Current concepts of prolacting physiology in normal and abnormal conditions

Prolactin response to thyrotropin-releasing hormone in women with infertility and/or randomly elevated serum prolactin levels

Infertile women with normal serum prolactin (PRL) levels have been known to establish a pregnancy after the use of bromocriptine, a dopamine agonist. These data imply that there may be a group of women with a slight but significant increase in PRL secretion that may have resulted in their infertility. This study evaluates the thyrotropin-releasing hormone (TRH)-induced PRL and thyroid-stimulating hormone (TSH) response in normal women (NL, n = 6), women with anovulation and/or inphase endometrial biopsies (AN/IN, n = 12), and women with histologic evidence of luteal phase deficiency (LPD, n = 12). Most of these women were found to have elevated serum PRL values on random testing. There was a statistically significant increase in PRL response at all time intervals after TRH between the NL and AN/IN groups compared with the group with LPD on the basis of repeated measures analysis (P = 0.0013). There was no statistical difference in the TSH response between these three groups. Although the PRL response was statistically different, individual PRL response patterns were not diagnostic. It appears from these data that there is an increased PRL secretion in infertile women who have histological evidence of a LPD.

The diurnal variations of serum prolactin levels before and during pregnancy in normal and hyperprolactinemic patients

The pattern of 24-hour secretion of prolactin was evaluated in three normal pregnant subjects at the tenth, twenty-fourth, and thirty-sixth gestational week. A similar study was performed in three hyperprolactinemic subjects throughout the course of their gestations. The findings confirm the progressive rise in serum concentrations of prolactin throughout pregnancy in normal subjects, with a tendency to blunting of the ratio of the nighttime mean to the daytime mean ( meanss / meansa ) as pregnancy progresses. One hyperprolactinemic subject (nontumoral) followed this pattern but demonstrated blunting initially and throughout pregnancy. The other two hyperprolactinemic subjects (one tumoral and one nontumoral) demonstrated an unexpected response in that they remained unresponsive to the increasing concentrations of estradiol throughout pregnancy.

Maternal serum hormone changes during abortion induced with 9-deoxo-16, 16-dimethyl-9-methylene prostaglandin E2

Serum hormone levels in women undergoing successful first and second trimester abortions induced by 9-deoxo-16, 16-dimethyl-9-methylene prostaglandin E2 vagitories have been measured. Significantly decreased levels of prolactin (p less than 0.01) and TSH (p less than 0.05) were seen in both groups of women but the drop appeared sooner, within two hours, in first trimester abortions. Regardless of gestational length there was a significant decrease in serum human chorionic gonadotropin (hCG) (p less than 0.01) concentrations in maternal serum six hours into treatment. In the second trimester abortions total estriol, alpha-fetoprotein and lactoplacental hormone hPL were analysed in maternal serum but the levels did not change over the eight hour investigation period. It is speculated that the PGE2-derivative most likely affects the maternal pituitary secretion of prolactin and TSH, possibly via direct or indirect interference with TRH mechanism(s).

Practical enzyme immunoassay for prolactin in human serum

We have developed a competitive enzyme immunoassay for prolactin in human serum. Serum samples were incubated at 4 degrees C for 48 h with anti-prolactin antibodies and prolactin labeled with beta-D-galactosidase. The antibody-bound form of labeled prolactin was separated from the unbound form by a method based on the thiol-disulfide interchange reaction. By measuring the enzyme activity, serum prolactin could be determined. Sensitivity of the assay was 2.5 ng/ml, and the assay was as sensitive as radioimmunoassay. There was a good correlation between the values obtained by the enzyme immunoassay and those obtained by a radioimmunoassay (r = 0.98, slope = 1.26, y-intercept = - 12.8 ng/ml).

Serum prolactin levels of non-cycling buffaloes ()

Prolactin levels were quantified by double antibody radio-immunoassay in the blood sampled daily for 24 days, from 9 non-cyclic Murrah buffaloes during hot months (ambient temp.41 to 43 degrees C). All buffaloes were kept in open loose housing. Three buffaloes were sprinkled with water for half an hour twice daily between 1200 and 1430 h to overcome partly the effect of heat during the period of investigation. Mean prolactin levels of 6 unsprinkled buffaloes ranged on different days from 249 to 739 ng/ml serum. The range of averages in case of 3 sprinkled animals was from 152 to 342 ng/ml serum. Buffaloes subjected to sprinkling had significantly (P / 0.01) lower prolactin levels than control buffalo.

Conservative management of suspected prolactin secreting pituitary adenoma during pregnancy

Seventeen women with prolactin levels of 100 ng/ml and above suspected of harboring prolactin-secreting pituitary adenoma, from the basis of this study. Ten patients had radiological signs of an adenoma while in 7 the radiological criteria for such a diagnosis were not fulfilled. Ovulation and pregnancy were induced with bromocriptine in all 17 patients. They were carefully observed during pregnancy and following delivery. All gave birth to full-term babies after uneventful pregnancies, except for one patient who experienced intrauterine fetal death at 31 wk of gestation. It is our policy that women with suspected intrasellar prolactin-secreting pituitary adenoma be allowed to conceive and give birth without previous surgical intervention. The patient should be closely followed during pregnancy for clinical symptoms of enlargement of the tumor, including periodic visual field examinations. In cases of neurologic or ophthalmologic complications, surgery or bromocriptine administration without interruption of pregnancy is advocated, or if lung maturity is achieved, delivery should be induced.

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.

Prolactin--added dimension in male genitosexual disorders

Prolactin-producing pituitary adenomas known to cause amenorrhea and galactorrhea in the female have been implicated recently in male infertility and impotence. Knowledge of the pathophysiology of prolactin and of the choices of treatment for these tumors is an important adjunct to the urologist's armamentarium.

Male hyperprolactinemia:effects on fertility

Male hyperprolactinemia was detected in 4% (7 of 171) of infertile men. In seven patients with excessive serum prolactin concentrations, the clinical manifestations were infertility, hypogonadism, impotence, and galactorrhea and the etiologic factors were pituitary adenoma, hypothalamic dysfunction, drug use, and idiopathic. The testes and prostate were small or normal and the semen analysis revealed low semen volume, normal or low sperm count, and normal or impaired sperm motility. The testicular biopsy showed normally preserved seminiferous tubules with normal or decreased spermatogenesis and damaged or fibrotic seminiferous tubules among normal ones. Patients with hyperprolactinemia were investigated by sellar polytomography, visual field examinations, and hormone assays. Treatment with bromocriptine (Parlodel) gave satisfactory results in all patients. The use of bromocriptine with human menopausal gonadotropin and human chorionic gonadotropin was beneficial in treating hypogonadotropic hypogonadism with hyperprolactinemia.

Hypothalamic-pituitary function and radiographic evaluation of women with hyperprolactinemia and an "empty" sella turcica

A primary "empty" sella may be associated with significant hypothalamic-pituitary dysfunction. This report characterizes the endocrinologic and radiographic findings in six patients with hyperprolactinemia (range 34.3 to 1,170 ng/ml) ultimately found to have an enlarged empty sella. Lateral skull x-ray films and thin-section tomograms were suggestive of pituitary tumors in all patients. Four patients underwent transphenoidal sellar exploration after pneumoencephalography (PEG) failed to demonstrate air within the sella. The inability of PEG to demonstrate an empty sella in two patients was explainable on the basis of an intact diaphragma sellae with previous transient intrasellar pathology responsible for the sellar enlargement. Dynamic hypothalamic-pituitary testing yielded no consistent pattern of response. These studies suggest that an empty sella: (1) may be associated with hyperprolactinemia, regardless of etiology, (2) is not diagnosable by dynamic hormonal testing, and (3) may be indistinguishable from a pituitary tumor by current radiographic techniques.

Current management of the amenorrhea-galactorrhea syndrome

Management of the amenorrhea-galactorrhea syndrome has changed considerably in the last 5 years. Better understanding of the neuroendocrine physiology of the central nervous system in general, and of the hypothalamic-pituitary region in particular, have contributed significantly to our understanding of the pathophysiology of this syndrome. Greater awareness by physicians, improved neuroradiologic techniques, and the development of immunoassays for prolactin have markedly improved our diagnostic abilities. Many more patients are being diagnosed as having a pituitary tumor. The recent introduction of microneurosurgical techniques and the new medications (ergolines) are changing the treatment of this syndrome. Women in the childbearing age--who are affected most often--can expect successful treatment in the majority of cases with resumption of normal menstrual function and fertility. However, certain risks are still posed, particularly during pregnancy. In spite of improved diagnosis and treatment, the natural history of prolactin-secreting pituitary tumors and the long-range effects are still not fully appreciated. More experience in time will be needed before the indications for and the efficacy of various treatment regimens are fully known.