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Anorexia nervosa (AN) and bulimia nervosa (BN) are currently classified as eating disorders. Both disorders are the product of a complex interaction between psychological and physiological processes and both show considerable comorbidity with other psychiatric disorders. Physiological and endocrine abnormalities, including primary or secondary amenorrhea and menstrual dysfunction, are common and for the most part a function of the severity of weight loss, malnutrition and/or abnormal eating habits. Therefore, assessment needs to include several steps: (1) Clinical evaluation to ascertain the diagnosis, including weight and height measurements; (2) Determination of co-existing psychiatric illnesses; and (3) Physical examination and evaluation of the physiological and endocrine status. Eating disorders interfere with reproductive function. In view of the fact that dieting has reached epidemic proportions among the young female population, and given the high association between eating disorders and endocrine abnormalities as well as menstrual disturbances, all women participating in research studies should be screened for the presence of eating disorders, disordered eating, and excessive exercise.     

Anti-prolactin (PRL) autoantibodies cause asymptomatic hyperprolactinemia: bioassay and clearance studies of PRL-immunoglobulin G complex

The causes of hyperprolactinemia are varied, but some cases are classified as "idiopathic" because of unknown causes. We examined whether anti-prolactin (PRL) autoantibodies can cause hyperprolactinemia, especially the asymptomatic type. Serum PRL in four women with anti-PRL autoantibodies and five control patients with prolactinoma was characterized by a sensitive enzyme immunoassay, Nb2-bioassay, gel chromatography, affinity chromatography for immunoglobulin G (IgG), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under nonreducing conditions, and clearance studies using anesthetized rats. In four women with anti-PRL autoantibodies, serum immunoreactive PRL concentrations were elevated (326 +/- 216 micrograms/L, normal < 30 micrograms/L), and PRL (84 +/- 5.5%) mostly consisted of the large molecular form in which a significant amount of 23 kDa PRL (60.6 +/- 14.7%) was noncovalently bound to IgG. Although three of the four women lacked clinical symptoms of hyperprolactinemia such as amenorrhea and galactorrhea, the IgG-bound PRL was fully bioactive in vitro. It was cleared more slowly from circulation than free PRL. The data suggest that PRL forms a complex with IgG, and this probably results in delayed clearance of PRL and leads to hyperprolactinemia in women with anti-PRL autoantibodies.     

mtDNA variation in caste populations of Andhra Pradesh, India

The aim of the study was to determine the association between PRL responses to suckling and maintenance of postpartum amenorrhea among breastfeeding mothers. Three blood spot samples (5, 30, and 50 min following a timed nursing bout) were collected from 71 intensively breastfeeding Nepali women for PRL determination. Maternal age, BMI (weight/height2), menstrual status, caste, infant age, nursing bout length, and duration of supplementation were recorded at time of sample collection. Independent and paired t tests, linear regression analyses, and general linear models were used to evaluate differences between cycling (n = 36) and amenorrheic (n = 35) women and associations among variables. Logistic regression analyses were used to relate PRL measures to the odds of maintaining lactational amenorrhea. Amenorrheic breastfeeding mothers had higher (P < .001) PRL levels at all 3 collection times than cycling breastfeeding mothers, and PRL levels declined with time since birth (P < 0.05). The odds (OR) of having ceased lactational amenorrhea was significantly higher (OR = 5.0, 95% Cl = 1.3-19.9) among mothers with lower PRL levels (< or = 10 ng/mL) at 50 min post-sucking, and PRL at 50 min showed a significant dose response relationship with menstrual status. The association between 50 min PRL levels and lactational amenorrhea appears to be independent of time postpartum, maternal age, BMI, nursing bout length, and duration of supplementation. Among intensively nursing women, maintenance of elevated PRL levels across the interbout interval increases the odds of maintaining lactational amenorrhea.     

Hypergonadotropic secondary amenorrhea: clinical analysis of 126 cases

OBJECTIVE: To study the etiology and early diagnosis of hypergonadotropic amenorrhea and to explore the appropriate treatment for preserving their reproductive function. METHODS: 126 cases of secondary amenorrhea with serum follicular stimulating hormone (FSH) levels > or = 40 IU/I, were analysed. Their clinical manifestations, karyotypes, ovarian morphology and histology, reproductive hormone assays, and responses to estrogen therapy and ovulation induction were studied. RESULTS: 6 cases presented with histories of ovarian surgery, radiotherapy or chemotherapy. Among the other 120 cases, 18 manifested amenorrhea before or at 25 years of age, 102 developed amenorrhea after age 25. In the former group, 16 (88.9%) showed unilateral or bilateral gonadal dysgenesis, and the other 2(11.1%) were defined as resistant ovaries. Abnormalities of sex chromosome karyotype occurred in 44.4% (8/ 18). In the latter group, 68 underwent laparotomy or laparoscopy examination. Morphological and histological examinations of both ovaries showed atrophic ovaries in all cases accompanied by 30.9% (21/ 68) unilateral gonadal dysgenesis; sex chromosomal abnormality was found in only one with no sexual immaturation. The efficacy of estrogen treatment was significantly better among cases with amenorrhea less than 1 year as compared with those longer than 1 year. Clomiphene challenge test given to 8 cases during their irregular menstrual stages produced an elevation of FSH levels to > 20 IU/I. without any response of estradiol secretion. CONCLUSIONS: The earlier estrogen therapy is initiated, the greater possibility of pregnancy will be achieved in cases suffering from hypergonadotropic amenorrhea. The clomiphene challenge test may provide evidence of waning ovarian function for early diagnosis.     

Prolactin bioactivity and the duration of lactational amenorrhea

In our population, only half of fully nursing women remain amenorrheic 6 months postpartum. The other half recover their menstrual cycles between 90-180 days postpartum in spite of a high suckling frequency and elevated immunoreactive PRL (IR-PRL) concentrations. To further investigate the association of PRL with the recovery of ovarian function, we compared PRL bioactivity (BIO-PRL) 3-4 months postpartum in fully nursing amenorrheic women who subsequently experienced long (> 180 days; n = 5) or short (< 180 days; n = 5) lactational amenorrhea. In the present study, BIO-PRL in plasma was measured by the Nb2 lymphoma cell assay in samples taken before and 30 min after a suckling episode at 0800, 1600 and 2400 h. Women in the long amenorrhea group had higher overall mean BIO-PRL (mean +/- SE, 129.9 +/- 12.1 micrograms/L) than nursing women in the short amenorrhea group (66.6 +/- 5.2 micrograms/L; P < 0.05). Mean basal values were similar, but the women in the long amenorrhea group had more BIO-PRL in response to suckling (160.1 +/- 4.0 vs. 71.9 +/- 6.7 micrograms/L; P < 0.05). Compared with their respective basal values, nursing women in the long amenorrhea group demonstrated increased BIO-PRL in response to suckling, whereas the other group did not. The relationships between BIO-PRL and IR-PRL were similar in the two groups of nursing women before suckling. However, after suckling, the long amenorrhea group had significantly higher BIO-PRL levels than IR-PRL levels (P < 0.05, by likelihood test) than the short amenorrhea group. This suggests that suckling differentially changes in each group either the composition of PRL present or substances that may modify the bioactivity of PRL in plasma.     

Galactorrhea

Galactorrhea syndromes are mainly caused by hyperprolactinemia, which has been defined by the basal prolactin level more than 15 ng/ml. However, normoprolactinemia can not be proved only by the basal prolactin level less than 15 ng/ml, which required the assessment of prolactin secreting capacity. Occulted hyperprolactinemia has be well known as the same syndrome as hyperprolactinemia, which shows basal prolactin level less than 15 ng/ml and the exceed response of prolactin to prolactin secreting stimulation like as thyroid releasing hormone. Women with occulted hyperprolactinemiais show temporary and intermitted hyperprolactincmia responding to a lot of atimulous states like as stress, sleep or elevated E2 level, which resulted in galactrrhea, menstrual disturbances or infertility. The elevated prolactin not only suppress the pituitary ganadotropin secretion, but also disturb follicular development and luteal function in the ovary. Dopamine agonists, bromocriptine and teruguride an usually indicate in the treatment of hyperptolactinemia and have brought the good results.     

Different sensitivity to sodium valproate in healthy, non-tumoral and tumoral hyperprolactinemic subjects

GABAergic drugs affect PRL secretion in both rat and man. Sodium valproate (SV) inhibits GABA transaminase so increasing the endogenous GABAergic tone. The aim of this study was to evaluate the effects of SV at low and high doses on PRL release in healthy subjects and hyperprolactinemic patients. Fifteen patients with prolactinomas, 8 patients with non-tumoral hyperprolactinemia and 10 healthy subjects were studied: in non consecutive days, all subjects received placebo and SV at the dose of 400 and 800 mg po. Serum PRL levels were assessed 30, 15 and 5 min before and every 30 min for 4 hours after administration. SV at the dose of 400 mg induced a significant decrease of serum PRL in healthy subjects (p < 0.05), whereas no effect was noted in both tumoral and non-tumoral hyperprolactinemia. The administration of 800 mg SV induced a significant decrease of PRL levels in healthy subjects and in patients with non-tumoral hyperprolactinemia (p < 0.05). Conversely, in prolactinomas a paradoxical increase of serum PRL concentration (p < 0.05) was observed 120 min after the administration of the drug. These data confirm the inhibitory activity of SV on PRL release in healthy subjects, and suggest the existence of a partial resistance to GABA in non-tumoral hyperprolactinemia. In prolactinomas, the paradoxical PRL increase after high dose of SV suggests the existence of a complete pituitary resistance to GABA. This finding might be explained by the appearance of the stimulatory effect of GABA at hypothalamic level that could have been unmasked by the lack of pituitary GABA effects on adenomatous lactotrophs.     

Heart arrest during dipyridamole scintigraphy: report of 3 cases

Potentially life threatening rythm disturbances, such as third degree A-V block and sinus arrest without "escape rythm", represent infrequent and unexpected events during dipyridamole thallium scintigraphy. We report three cases of cardiac arrest requiring resuscitation maneuvers after dipyridamole infusion during myocardial thallium scan. On the basis of these clinical observations we suggest that a trained cardiologist and resuscitation kit should be available in nuclear lab. Moreover elderly patients may require careful screening for preexisting conduction defects and sick sinus syndrome. When dipyridamole infusion provokes severe bradyarrhythmias not related to myocardial ischemia, a transesophageal electrophysiological study should always be performed.     

Nitric oxide plays an important role in the diurnal change of tuberoinfundibular dopaminergic neuronal activity and prolactin secretion in ovariectomized, estrogen/progesterone-treated rats

A significant diurnal change of tuberoinfundibular dopaminergic (TIDA) neuronal activity coincident with the estrogen (E2)-induced afternoon PRL surge has been reported in ovariectomized, E2-primed (OVX+E2) rats. Systemic injection of a nitric oxide (NO) synthase (NOS) inhibitor, N(G)-nitro-L-arginine (L-NA, 50 mg/kg, i.p. at 1000 and 1200 h), significantly blocked the diurnal changes of TIDA neuronal activity and PRL secretion at 1500 and 1700 h in OVX+E2 rats. Coadministration of L-arginine (300 mg/kg, i.p.) with L-NA completely prevented the effects of L-NA. Total nitrite/nitrate levels in the serum of L-NA- and L-NA+L-arginine-treated rats substantiated the effects of L-NA and L-arginine on NO production. Pretreatment of antisense oligodeoxynucleotide (ODN; 1 microg/3 microl; intracerebroventricularly at 48, 24, and 7 h before sacrifice) against the messenger RNA (mRNA) of constitutive NOS, i.e. neuronal NOS or endothelial NOS, was also effective in preventing the diurnal changes of TIDA neuronal activity and PRL surge at 1500 h. The same treatment of antisense ODN against the mRNA of inducible NOS, i.e. macrophage NOS, had no effect. Progesterone (P4) has been reported to advance and augment the diurnal changes of TIDA neuronal activity and the afternoon PRL surge, by 1 h, in both proestrous and OVX+E2 rats. We further showed that L-NA dose dependently (50 but not 5 mg/kg, i.p. at 1000 and 1200 h) blocked the effect of P4 on TIDA neurons and serum PRL at 1300 h, which effect could be negated by simultaneous administration of L-arginine (300 mg/kg, i.p.). Pretreatment with antisense ODNs against the mRNA of neuronal NOS or endothelial NOS, but not macrophage NOS, was also effective in preventing the P4's effect on TIDA neuronal activity and PRL secretion at 1300 h. In summary, NO may play a physiological role in the E2- and P4-regulated diurnal changes of TIDA neuronal activity and PRL secretion.     

Treatment of women with the galactorrhea-amenorrhea syndrome with pyridoxine (vitamin B6)

Three women with the galactorrhea-amenorrhea syndrome and elevated prolactin concentrations experienced a return of regular ovulatory menses within 37-94 days after starting pyridoxine treatment (200-600 mg/day). In each the galactorrhea ceased and serum prolactin levels were maintained in the normal range while taking pyridoxine. In two other women with prolonged secondary amenorrhea but without hyperprolactinemia or galactorrhea, pyridoxine at dosages up to 600 mg/day did not restore ovulatory menses. Pyridoxine treatment was also ineffective in decreasing profuse galactorrhea in one woman with normal prolactin levels and regular ovulatory menses. In the three women effectively treated with pyridoxine, the galactorrhea returned, serum prolactin levels increased, and the menses ceased after discontinuing pyridoxine. These results imply that pyridoxine, by decreasing the excessive secretion of prolactin, may be useful in the long-term medical management of women with hyperprolactinemia and the galactorrhea-amenorrhea syndrome.     

Neurophysiological evaluation of sexual dysfunction in patients operated for colorectal cancer

Severe dieting and negative energy balance usually lead to the occurrence of amenorrhea together with several endocrine disturbances such as the "low T3 syndrome" and an abnormal GH secretion. To evaluate whether estrogen replacement therapy (ERT) affects thyroid hormones and GH secretion, two groups of patients affected by weight-loss-related amenorrhea and with low plasma T3 levels were treated with two different schedules of ERT using 50 or 100 micrograms estradiol transdermal patches twice a week (Dermestril, Rottapharm, Monza, Italy). Before and after 5 weeks of therapy in each patient thyroid hormones, spontaneous GH secretion and GH-RH-induced GH release were evaluated. After ERT, plasma GH and IGF-1 levels increased in both groups and a consistent change in GH spontaneous release was observed. Conversely the low T3 plasma levels and GH-RH-induced GH response were not modified by ERT. Our present data suggest that in amenorrhea related to weight-loss, hormonal abnormalities are only in part dependent from the hypoestrogenic condition.     

Effect of prolactin suppression on gonadotrophic secretion in the puerperium

Serum levels of prolactin (PRL), FSH, LH and oestradiol-17 beta were determined by radioimmunoassay in 57 lactating women and in 20 women in whom lactation was inhibited by ergocryptine (CS-154). Women who breast fed their infants exhibited high PRL levels which abruptly declined within 48 h post-partum, and remained low for the duration of the study. Serum FSH was undetectable during the first week post-partum in lactating as well as in CB-154 treated women. Thereafter, lactating women showed increasing FSH levels which reached a maximum by the third week post-partum. These FSH values were higher in lactating women than in the CBS-154 treated group. In contrast, LH levels were higher in those women receiving CB-154. Serum oestradiol-17 beta remained in low levels throughout the study, and no difference was observed between the two groups of subjects. From these results it seems that: 1) inhibition of PRL secretion leads to a faster recovery of gonadotrophin secretion toward the "menstrual type", and 2) PRL suppression produces no effect on the ovarian oestrogen production.     

Hypothalamic-pituitary-adrenal axis function in patients with active rheumatoid arthritis: a controlled study using insulin hypoglycemia stress test and prolactin stimulation

OBJECTIVE: To study the response of cortisol and of prolactin (PRL) to specific stimuli in rheumatoid arthritis (RA). METHODS: We measured the response of cortisol to insulin induced hypoglycemia and of PRL to thyrotropin releasing hormone (TRH) in 10 patients with active RA and in 10 paired control subjects. All were women with regular menstrual cycles. They had never received corticosteroids before the study. The PRL concentration was assessed by chemiluminescence immune assay and the cortisol concentration by radioimmunoassay. RESULTS: The basal serum levels of cortisol (14.47+/-2.5 microg/dl) and PRL (10.1+/-1.3 ng/ml) in the RA group were not significantly different from those of the control group (12.3+/-1.1 microg/dl and 13.7+/-2.4 ng/ml, respectively). The peak value of cortisol after hypoglycemia was comparable in both groups (25.5+/-2.4 microg/dl in RA vs. 26.0+/-1.5 ng/ml in controls). The integrated cortisol response to hypoglycemia expressed as area under the response curve (AUC) did not differ significantly in either group (1927+/-196 in RA vs. 1828+/-84 in controls). The interval-specific "delta" cortisol response was significantly higher for the 30 to 45 min interval in controls compared to patients with RA (9.8+/-0.9 microg/dl vs. 6.1+/-1.1 microg/dl; p = 0.02). The peak of PRL after TRH did not differ significantly in both groups (56.4+/-6.4 ng/ml in RA vs. 66.3+/-7.7 ng/ml in controls) and the AUC of PRL secretion after TRH was comparable in both groups (3245+/-321 vs. 4128+/-541). CONCLUSION: Our findings suggest that active RA is associated with subtle dysfunction of the hypothalamic-pituitary-adrenal glucocorticoid function and normal PRL secretion.     

Enhanced slow wave sleep in patients with prolactinoma

Bidirectional interactions between nocturnal hormone secretion and sleep regulation are well established. In particular, a link between PRL and rapid eye movement (REM) sleep has been hypothesized. Short-term administration of PRL and even long-term hyperprolactinemia in animals increases REM sleep. Furthermore, sleep disorders are frequent symptoms in patients with endocrine diseases. We compared the sleep electroencephalogram of seven drug-free patients with prolactinoma (mean PRL levels 1450 +/- 1810 ng/mL; range between 146 and 5106 ng/mL) with that of matched controls. The patients had secondary hypogonadism but no other endocrine abnormalities. They spent more time in slow wave sleep than the controls (79.4 +/- 54.4 min in patients vs. 36.6 +/- 23.5 min in controls, P < 0.05). REM sleep variables did not differ between the samples. Our data suggest that chronic excessive enhancement of PRL levels exerts influences on the sleep electroencephalogram in humans. Our result, which seems to be in contrast to the enhanced REM sleep under hyperprolactinemia in rats, leads to the hypothesis that both slow wave sleep and REM sleep can be stimulated by PRL. These findings are in accordance with reports of good sleep quality in patients with prolactinoma, which is in contrast to that of patients with other endocrine diseases.     

Vessel boundary extraction based on a global and local deformable physical model with variable stiffness

BACKGROUND: Oligomenorrhea, defined as a menstrual cycle lasting 36 to 90 days, can be a normal condition in the first years after the menarche. When it persists or appears after a period of normal menstrual cycles, an underlying illness must be sought. AIM: To assess ovulation and causes of anovulatory cycles in women with oligomenorrhea, compared with causes of secondary amenorrhea. PATIENTS AND METHODS: One hundred one women of less the 35 years old, presenting with oligomenorrhea persisting 5 years after menarche or lasting more than two years after a period of normal menstrual cycles, were studied. Ovulation was studied measuring serial plasma progesterone during normal or induced (with intramuscular progesterone) menstrual cycles. RESULTS: Eighty nine percent of women had anovulatory oligomenorrhea. The main causes were polycystic ovarian disease in 51% and hypothalamic dysfunction in 31%. Thirty percent of women with secondary amenorrhea had polycystic ovarian disease and 14% had hyperprolactinemia. Women older than 20 years old or with more than 10 years of gynecological age had a higher frequency of polycystic ovarian disease and a lower prevalence of hypothalamic dysfunction. CONCLUSIONS: There is a high frequency of anovulatory oligomenorrheas. Therefore, this symptom deserves a thorough endocrinological assessment to uncover underlying diseases. Special attention must be paid to polycystic ovary syndrome, due to its importance in internal medicine as a risk factor for myocardial infarction, high blood pressure, and type 2 diabetes mellitus.     

Prolactin: the initial luteotropic stimulus of pseudopregnancy in the rat

The luteotropic stimuli necessary to transform the corpus luteum of the estrous cycle into a corpus luteum of psuedopregnancy on the morning of diestrus-2 (Day 2), as reflected by a dramatic divergence in progesterone secretion, were studied (Day 1 was taken as the first day of diestrus of pseudopregnancy). The requirement of prolactin (PRL) as a luteotropic stimulus was determined by inhibiting the diurnal and nocturnal PRL surges that occur immediately before and during the divergence in progesterone. Following cervical stimulation, 1 mg of 2-Br-alpha-ergocryptine (EC) was injected at 1100 and 2300 h on Day 1 (lights on 0600-1800 h), and the animals were decapitated at 2-4 h intervals from 1100 h on Day 1 to 1700 h on Day 2. In the control animals, the PRL surges on Day 1 and Day 2 were associated with an increase in progesterone secretion on Day 2. However, the regimen of EC treatment resulted in an inhibition of PRL surges, prolactin remaining at baseline values from 1100 h on Day 1 to 1700 h on Day 2. The inhibition of PRL secretion was associated with a fall in progesterone concentration to reach baseline values by 1700h on Day 2. Furthermore, a group of animals similarly treated with EC returned to vaginal estrus 2 days later. LH concentrations did not differ in control and EC-treated animals. The effect of EC on corpus luteum function could be completely reversed by the simultaneous administration of PRL. In addition, if PRL was administered at 1100 h and 2300 h on diestrus-1 of the estrous cycle, in an attempt to mimic the surges os pseudopregnancy, regression of the corpora lutea did not occur. Progesterone levels increased to reach values comparable to those observed in pseudopregnancy on diestrus-2. The role of LH was studied by administering a dose of LH antiserum at 110 and 2300 h on Day 1 of pseudopregnancy. This treatment failed to inhibit the increase in progesterone observed on Day 2. These results demonstrate that the surges of plasma PRL initiated by cervical stimulation are responsible for transforming a corpus luteum of the estrous cycle into a corpus luteum of pseudopregnancy, as reflected by an increase in progesterone secretion of Day 2. LH seems to have a minor role in maintaining corpus luteum function beyond that observed during the estrous cycle.     

Beyond global oxygen supply-demand relations: in search of measures of dysoxia

Variations in serum molecular forms of prolactin (PRL) from an adolescent woman presenting amenorrhea-galactorrhea are reported. Persistent hyperprolactinemia and hypoestrogenism were demonstrated as well as the presence of a pituitary tumor with suprasellar extension. Bromocriptine was given at progressive doses up to 37 mg daily, decreasing the hyperprolactinemia and galactorrhea. After 2 years of treatment the patient noticed symptoms of gastric intolerance, bromocriptine was discontinued and a rebound of hyperprolactinemia was observed. Lisuride was administered instead resulting in a new decrease in PRL serum levels, disappearance of galactorrhea and beginning of regular menses. Serum gel chromatographic analysis was carried out before and during lisuride treatment. The first chromatographic analysis showed a predominance of high molecular weight (approximately 66 KD) PRL, accounting for more than 90% of the immunoreactive PRL. The second chromatography showed the major peak of immunoreactive PRL displaced to the right (molecular weight of 22 KD), which was eluted near the PRL standard. With these chromatographic patterns it is concluded that the pituitary macroprolactinoma secreted different molecular forms of PRL and treatment with lisuride appeared to exert some effect on the PRL molecular size secreted by the pituitary.     

A study on sexual dysfunction in female patients with alcoholics

Few investigations have been made concerning hormonal changes and dyspareunia in fertile aged women with alcoholics experiencing sexual dysfunction. Twenty-seven Japanese woman with alcoholics under 40 years of age excluded with liver cirrhosis were studied to describe alcohol drinking related to sexual dysfunction. Among 21 sexually active women, 20(95.2%) had both symptoms of dyspareunia and vaginal dryness, and only one had neither symptom. Most of patients have lower estradiol levels and 92.0% of patients have the moderately elevated prolactin levels. Eleven of them were having the second grade amenorrhea associated with hyperprolactinemia and hypergonadotropic hypogonadism and 14 were having the first grade amenorrhea. In this study alcoholic abuse women may have deeply related to the hyperprolactinemia, dyspareunia, amenorrhoea, vaginal dryness, ovarian dysfunction and fetal alcohol syndrome.     

The forms of vitamin B12 on the transcobalamins

Prolactin (PRL) secretion in the periparturitional period in patients undergoing labor and vaginal delivery follows a remarkable multiphasic pattern not found in patients who underwent elective cesarean section without labor. There is a highly significant decline in PRL levels during active labor which reaches a nadir about two hours prior to delivery. Immediately after delivery, a surge of PRL is noted, reaching peak levels within two hours post partum. Thereafter, PRL levels fall, reaching a second nadir about nine hours post partum, and this low level is maintained for nine to 24 hours after delivery. This multiphasic pattern of PRL secretion is not correlated with changes in serum concentrations of cortisol, progesterone, estradiol, or estrone. PRL levels in all pregnant patients at term were unaffected by the administration of synthetic narcotic analgesic agents, anesthesia, or the stress of operation. It is concluded that PRL secretion in the pregnant patient at term is unresponsive to usual stimuli and that the multiphasic pattern of PRL secretion uniquely found with labor and vaginal delivery may be associated with dopaminergic neuroendocrine processes during human parturition.