Luteinizing Hormone Values Research Articles

Inhibin and gonadotrophin secretion in physically active males after acute exercise

Serum concentrations of luteinizing hormone (LH) follicle stimulating hormone (FSH), testosterone and inhibin were measured in six physically active male volunteers after heavy exercise on a treadmill. Hormone measurements were made before exercise, immediately after exercise and at 30-min intervals for 3 h after exercise. Serum concentrations of LH fell after exercise reaching nadir values between 60 and 180 min post-exercise. The nadir value of LH for the group as a whole occurred 90 min after exercise. Serum testosterone concentrations paralleled the changes in LH concentrations. Serum FSH and inhibin concentrations did not show any appreciable change from baseline values. The data suggest that acute exercise does not significantly lower serum concentrations of FSH or inhibin. Whether repetitive and prolonged heavy exercise, as in competitive runners, produces alterations in serum inhibin concentrations remains to be determined.

Hypersecretion of Luteinising Hormone, Infertility, and Miscarriage

Abstract The relation between prepregnancy follicular-phase serum luteinising hormone (LH) concentrations and outcome of pregnancy was investigated prospectively in 193 women with regular spontaneous menstrual cycles. The group included 26 nulliparous and 167 multiparous women with various obstetric histories. Of the 147 women with LH concentrations of less than 10 IU/I (normal LH group) 130 (88%) conceived, whereas only 31 (67%) of the 46 women with LH values of 10 IU/I or more (high LH group) did so. In the high LH group, 20 (65%) of the pregnancies ended in miscarriage, whereas only 15(12%) of pregnancies in the normal LH group did so. The adverse effect of a high prepregnancy LH concentration on fertility and outcome of pregnancy was seen in primigravidae, women with previously successful pregnancies, and women with a history of recurrent miscarriage. These data indicate an important role for hypersecretion of LH before conception in miscarriage. This finding offers the possibility of a simple predictive test for women before pregnancy, and could also be used to identify patients with an endocrine abnormality that can be remedied.

High preovulatory serum luteinizing hormone level is unfavorable to conception

Serum estradiol, progesterone and luteinizing hormone (LH) levels of 16 pregnant and 58 non-pregnant stimulated in vitro fertilization-embryo transfer (IVF-ET) or gamete intrafallopian transfer (GIFT) cycles have been compared with regard to their predictive value for achievement of pregnancy. Serum estradiol and progesterone pattern of the pregnant and non-pregnant group did not show any significant difference. Around the time of ovulation induction by human chorionic gonadotropin (hCG) the serum LH values proved to be higher in the non-pregnant group than in the pregnant one. In spite of having a permissive function, preovulatory serum estradiol and progesterone seem not to have a predictive value with regard to pregnancy. Elevated preovulatory serum LH is detrimental for pregnancy, therefore the measurement of serum LH beyond hCG administration also, and the cancellation of cycles with high serum LH levels shortly before oocyte retrieval is recommended.

Hypothalamic opiatergic tone during pregnancy, parturition and lactation in the rat.

The concentrations of beta-endorphin have been shown to change in the rat brain during pregnancy and lactation. This study has been performed in order to analyze whether also brain opioid receptors might undergo significant modifications during these two physiological situations. The maximal binding capacity (Bmax) and the constant of affinity (Ka) of the mu-subpopulation of opioid receptors have been evaluated in the hypothalami of female rats at different stages of pregnancy (7, 15 and 22 days), on the day of parturition (12-18 h after delivery) and 6-8 days postpartum (both in lactating and in nonlactating animals). Female rats killed on the day of estrus served as controls. The receptor binding assay has been performed utilizing [3H]-dihydromorphine [( 3H]-DHM) as the ligand for the mu-opioid receptors. Hypothalamic concentrations of beta-endorphin as well as serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin have also been evaluated by radioimmunoassay. The results showed that the concentration of hypothalamic mu-opioid receptors increased during pregnancy, being significantly higher than in the controls at days 15 and 22 of gestation. After delivery, the concentration of these receptors returned towards control values, regardless on whether the animals were lactating or not. The Ka values of [3H]-DHM for the mu-receptors did not change significantly in the different groups of experimental animals. Hypothalamic beta-endorphin content showed a modest though not significant increase at the end of gestation (day 22) and returned to control values 12-18 h after delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Antiprogestin treatment decreases midluteal luteinizing hormone pulse amplitude and primarily exerts a pituitary inhibition

Mifepristone (RU 486), a synthetic steroid with antiprogesterone receptor activity, was given with and without naloxone hydrochloride to six women in the midluteal phase to investigate the role of progesterone in the modulation of endogenous opioid activity and the secretion of luteinizing hormone and cortisol. Subjects were evaluated during four sequential monthly admissions during which multiple blood samples were obtained every 15 minutes for 8 hours. Patients were studied during a baseline cycle, after administration of RU 486 alone (100 mg /day), naloxone with RU 486, and naloxone alone. After administration of RU 486 there was a significant decline in total luteinizing hormone secretion (p<0.01) and luteinizing hormone pulse amplitude (p<0.05), but compared with baseline there was no significant change in luteinizing hormone pulse frequency. After infusion of naloxone there was a significant increase in mean luteinizing hormone values (p<0.05) and luteinizing hormone pulse frequency (p<0.01) but no change in pulse amplitude. There was no significant difference in mean luteinizing hormone values or luteinizing hormone pulse amplitude and frequency between administration of RU 486 and naloxone plus RU 486. Administration of naloxone alone, RU 486 alone, and RU 486 plus naloxone caused a significant increase in cortisol as compared with baseline cycles (p<0.05). These data further support the notion that progesterone is important in the control of luteinizing hormone secretion and suggest that progesterone may primarily influence luteinizing hormone pulse amplitude and pituitary release of luteinizing hormone during the luteal phase.

Hypersecretion of luteinising hormone, infertility, and miscarriage

The relation between prepregnancy follicular-phase serum luteinising hormone (LH) concentrations and outcome of pregnancy was investigated prospectively in 193 women with regular spontaneous menstrual cycles. The group included 26 nulliparous and 167 multiparous women with various obstetric histories. Of the 147 women with LH concentrations of less than 10 IU/I (normal LH group) 130 (88%) conceived, whereas only 31 (67%) of the 46 women with LH values of 10 IU/I or more (high LH group) did so. In the high LH group, 20 (65%) of the pregnancies ended in miscarriage, whereas only 15(12%) of pregnancies in the normal LH group did so. The adverse effect of a high prepregnancy LH concentration on fertility and outcome of pregnancy was seen in primigravidae, women with previously successful pregnancies, and women with a history of recurrent miscarriage. These data indicate an important role for hypersecretion of LH before conception in miscarriage. This finding offers the possibility of a simple predictive test for women before pregnancy, and could also be used to identify patients with an endocrine abnormality that can be remedied.

'Acute on chronic' effect of depot leuprolide in patients with stage D2 cancer of prostate

During a phase III open study of depot leuprolide for stage D2 cancer of the prostate, we studied the effect of depot leuprolide on chronic leuprolide users. To determine whether there was a transient elevation of testosterone or luteinizing hormone (LH) 4-24 h and 3-5 days following the monthly injections, we monitored the changes of testosterone and LH before injection and 24 h post-injection in 10 patients who have been under depot leuprolide Rx for 24-36 weeks, and in 35 patients before injection and 3-5 days post-injection who have received depot leuprolide for 8-24 weeks prior to monitoring. Comparison of the data between pre-injection within 24 h and 3-5 days post-injection showed no significant changes of testosterone and LH values between these levels for either testosterone (P = 0.31) or LH (P = 0.45). We therefore conclude that there was no 'acute on chronic' effect of depot formulation in chronic users of depot leuprolide.

LUTEINIZING HORMONE AND FOLLICLE STIMULATING HORMONE SECRETION PATTERNS IN FEMALE ATHLETES WITH AND WITHOUT MENSTRUAL DISTURBANCES

Thirty-one young female athletes and 13 age-matched sedentary controls were studied throughout one menstrual cycle or over a 6 week period. Blood was sampled on 5 days per week. Episodic gonadotrophin secretion was measured in the early follicular phase and in the late luteal phase by blood sampling over a 12-h period at 15-min intervals. Eight athletes had anovulatory cycles, nine had impaired progesterone (P4) secretion during the luteal phase and 14 had normal cycles as judged from oestradiol (E2) and P4 plasma levels. Athletes with normal cycles had shorter cycles, lower E2 maxima at midcycle, and lower E2 and P4 concentrations during the luteal phase than had sedentary controls. Episodic luteinizing hormone (LH) secretion in the early follicular phase was significantly impaired in the anovulatory athletes: the average LH values over 12 h and the number of secretion episodes were significantly reduced. No significant changes were seen in follicle stimulating hormone secretion.

Naloxone antagonizes the morphine suppression of the oestradiol-induced surge of luteinising hormone in dairy cows

The study was designed to evaluate the effects of exogenous opiates on the release of luteinising hormone (LH) surge in response to oestradiol. Four intact and three ovariectomized cows released a normal LH surge after oestradiol benzoate alone. Four intact cows given morphine plus naloxone intravenously, 17 h after oestradiol benzoate, i.e. just before the expected time of onset of the LH surge, produced a normal LH surge. However, two of the four cows given morphine alone, 17 h after oestradiol, had no LH surge; one cow had a reduced response (peak value 21.6 ng/ml), the fourth had a normal LH surge. In the two latter cows, the surge of LH had either already started (LH values 7.7 and 10.3 ng/ml) before the morphine treatment, or was scheduled to occur after the effect of morphine was over, and remained unaffected or partially affected. In all other cows the LH values were basal (2.7 to 5.7 ng/ml) at this time. Similarly, an LH surge which started before or just after the morphine treatment 17 h after oestradiol in the three ovariectomized cows was not blocked but had a reduced amplitude. It is concluded that morphine can block, or suppress, the LH surge depending upon the time of treatment in relation to onset of the surge. This, and the antagonism of the effect by naloxone, supports the suggestion that in cattle the LH surge can be effected by the opioidergic interference, which might also be involved in aberrations of LH release in stressful situations that reduce fertility.

Dissociated effect of buserelin on luteinizing hormone (LH) and alpha subunit in men

Chronic treatment with LHRH analogs is known to depress testosterone (T) values to castration levels. In contrast to results from animal experiments, studies in humans indicate that a pituitary-dependent mechanism predominates in the suppression of plasma T. However, this reduction in T levels may occur when LH values are within or below the normal range. One explanation for this result has been that while absolute values of LH in serum may not change, the bioactivity of LH is reduced. The present study has been performed to determine whether this discrepancy between LH and T values is obscured by the hypersecretion of the alpha-subunit which is devoid of any biological activity but crossreacts in most RIAs with LH. Following 2 days of blood collection to establish basal serum hormone levels, six men with prostatic cancer were treated with the LHRH agonist, Buserelin (500 micrograms sc, daily injection) for 15 days. The most significant endocrine responses at the end of this treatment were as follows: 1) T levels were depressed to the castration range; 2) no change was seen in the LH values with a conventional RIA procedure which crossreacted with the alpha-subunit; 3) a significant decrease was found in the LH values evaluated with an immunoradiometric (IRMA) method, which shows no cross-reactivity with the alpha-subunit; 4) there was a significant increase in the alpha-subunit levels; and 5) serum FSH levels were significantly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

HORMONAL CHANGES IN PATIENTS WITH POLYCYSTIC OVARIAN DISEASE AFTER OVARIAN ELECTROCAUTERY OR PITUITARY DESENSITIZATION

Eleven patients with polycystic ovarian disease (PCO) were treated by laparoscopic ovarian electrocautery and nine with a long-acting luteinizing hormone releasing agonist (LHRH-A) for 8 weeks. Both groups showed equivalent significant decreases in their 6-h mean values of luteinizing hormone (LH) and testosterone (T) measured in 25 samples collected every 15 min. Patients treated with ovarian electrocautery showed significant increases in their 6-h mean values of follicle stimulating hormone (FSH) and insulin with variable oestradiol (E2) responses. The magnitude of change following treatment was significantly greater for LH than for FSH. Buserelin medication did not cause persistent significant changes in the levels of insulin or FSH but it did cause a significant reduction in the 6-h mean values of E2. We conclude that LH is the gonadotrophin primarily affected after pituitary desensitization and ovarian electrocautery. Furthermore, there is no direct correlation between the levels of circulating insulin and testosterone in patients with PCO.

Suppressive actions of a gonadotropin-releasing hormoneantagonist on luteinizing hormone, follicle-stimulating hormone, and prolactin release in estrogen-deficient postmenopausal women

We investigated time- and dose-dependent actions of a gonadotropin-releasing hormone antagonist, the "Nal-Glu" peptide [Ac-D2Nal1, 4CIDPhe2, D3Pal3, Arg5, DGlu6(AA), DAla10], in nine healthy estrogen-withdrawn postmenopausal women. Gonadotropin-releasing hormone antagonist was administered subcutaneously at doses of 10, 30, 100, and 300 micrograms/kg. Suppression of immunoactive luteinizing hormone concentrations was achieved with a 30 micrograms/kg dose of antagonist. Suppression of immunoactive follicle-stimulating hormone levels was less (40%) even at the highest antagonist dose (300 micrograms/kg). Bioactive luteinizing hormone concentrations also significantly decreased (greater than 60%) at the two antagonist doses tested (30 and 300 micrograms/kg). However, the lower antagonist dose showed an "escape" of bioactive luteinizing hormone values after 18 hours. No suppressive effects of the antagonist on prolactin secretion occurred at any dose tested. We conclude that this gonadotropin-releasing hormone antagonist can achieve effective, potent, and long-lasting suppression of pituitary secretion of biologically active luteinizing hormone at higher doses, but secretion of biologically active luteinizing hormone may "escape" at lower doses.

The effects of different cumulative doses of chemotherapy on testicular function. Results in 75 patients treated for Hodgkin's disease during childhood or adolescence

Testicular function was evaluated in 75 boys after treatment for Hodgkin's disease with involved-field or extended-field irradiation and stage-dependent chemotherapy (vincristine, prednisone, procarbazine, Adriamycin [doxorubicin], and cyclophosphamide [OPPA/COPP]). Although pubertal development and testosterone levels were normal in all patients, 18 of 75 (24.0%) had elevated basal and 65/74 (87.8%) elevated stimulated luteinizing hormone (LH) levels, demonstrating chemotherapy-induced Leydig cell damage. In addition, there was a 40.5% and 53.4% incidence of elevated basal and stimulated FSH values, respectively, indicating severe impairment of spermatogenesis as confirmed by azoospermia in four patients. Testicular dysfunction was observed in patients treated before as well as during puberty. The incidence of elevated basal follicle stimulating hormone (FSH) and LH values was significantly higher in patients who had received higher cumulative doses of chemotherapy, i.e., 28.9% and 13.2% with two OPPA, 45.5% and 36.4% with two OPPA/two COPP, and 62.5% and 43.8% with two OPPA/four to six COPP, respectively. Chemotherapy for Hodgkin's disease causes a high and apparently dose-related incidence of testicular dysfunction in prepubertal as well as in pubertal boys affecting Leydig cell function as well as spermatogenesis. Circumstantial evidence indicates that procarbazine is the major gonadotoxic agent involved.

Menstrual cycle characterization and artificial insemination in the black mangabey (Cercocebus aterrimus)

AbstractConcentrations of immunoreactive estrone conjugates, pregnanediol‐3‐glucuronide, and luteinizing hormone were measured and indexed to creatinine in daily urine samples from three female black mangabeys (Cercocebus aterrimus). Daily observations of menstruation and perineal tumescence were recorded. The mean ± SEM lengths of the menstrual cycle [apparent cycle length of 26.0 ± 0.8 days determined by observation of intermenstrual intervals (n = 26); physiologic cycle length of 31.3 ± 5 days determined by urinary endocrine analysis (n = 4)], follicular phase [16.5 ± 4 days (n = 4)], and luteal phase [14.8 ± 1 day (n = 4)] were determined. The apparent cycle length is probably more accurate.Perineal tumescence began during or shortly after menstruation, increased concomitantly with increasing follicular phase conjugated estrone values, and reached maximal size in the periovulatory period. Ovulation was closely followed by a drop in conjugated estrone levels, an increase in urinary pregnanediol‐3‐glucuronide, and perineal detumescence. Peak concentrations of conjugated estrone and luteinizing hormone values were coincident. Pregnanediol‐3‐glucuronide accurately reflected luteal function in the black mangabey.Knowledge of the menstrual cycle parameters and their correlation to perineal tumescence was used to time artificial inseminations. Semen was obtained by rectal electroejaculation. Coagulum and extended semen, or trypsin‐digested coagulum, were used for insemination. One insemination of trypsin‐digested coagulum at the external os of the cervix resulted in a probable conception, follówed by apparent abortion after 3 weeks.

Incidence of Polycystic Ovaries in Patients with Late-Onset or Persistent Acne: Hormonal Reports

Forty-six women affected by late-onset or persistent acne were studied in order to investigate the frequency of hormonal abnormalities and polycystic ovaries. Hirsutism, perioral distribution of acne lesions and irregular menses were recorded. Hormonal measurements and ovarian echographies were performed. Twenty-four patients were affected with polycystic ovaries, detected by ultrasound scanning. Among the acne patients, the women with ovarian abnormalities had higher values of androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate and luteinizing hormone (LH), and a higher LHT/follicle-stimulating hormone ratio than those with acne and without ovarian abnormalities. This study indicates the prevalence of polycystic ovaries in women with late-onset or persistent acne. Moreover, hormonal abnormalities indicate a subgroup of acne patients defined by the presence of ovarian disorders.

The Roles of Endogenous Opioids in the Inhibitory Action of the Hippocampus on Preovulatory of Luteinizing Hormone in Rats.

Whether endogenous opioid peptides were involved in the inhibitory action of the hippocampus (HPC) on luteinizing hormone (LH) release was studied examining the effect of naloxone, an opioid antagonist, on the inhibitory action of electrical stimulation of the HPC and also by examining the effect of metenkephalin administration in the HPC, on preovulatory release of LH in proestrous rats. In rats treated with saline at 13:00 h, either sham stimulation or electrical stimulation of the dorsal HPC, which was performed acutely under ether anesthesia, significantly inhibited the afternoon rise in serum LH. In animals treated with naloxone at a dose of 2.0 mg/kg body weight, the afternoon rise in LH appeared smaller than that in the control group. However, statistical analysis showed no significant difference in LH values compared to the control group. Direct administration of met-enkephalin at a dose of 10 micrograms at 13:00 h through a chronically implanted cannula in the HPC did not induce any significant change in the afternoon rise in LH, regardless of whether it induced behavioral seizures or not. The results suggest that opioid peptides in the HPC do not play a significant role in the inhibitory action of HPC on LH release. Opioids existing in areas other than the HPC may play a certain, but small role.

Opioid modulation of tonic luteinizing hormone release in ovariectomized dairy cows.

A possible role of endogenous opioid peptides (EOP) in regulating the release of luteinizing hormone (LH) in the absence of ovarian influence was investigated. Experiments were conducted on three lactating Holstein-Friesian dairy cows, 20-27 days after ovariectomy. The cows were bled before and after a single intravenous (i.v.) injection of either 250 mg of naloxone (EOP antagonist) or 300 mg of morphine (EOP agonist) or a combination of the two in Experiments 1, 2 and 3, respectively. The mean and basal LH concentrations and the LH pulse frequency and amplitude were compared before and after each treatment in each cow. Naloxone induced an immediate rise in LH concentration by 60-300% above the preceding baseline values. This rise lasted for 15-30 min in each cow, after which the normal rhythmic LH release continued. One cow (A) suffered discomfort and respiratory distress 15-25 min after naloxone administration and the mean and basal LH concentration dropped significantly. Morphine significantly reduced the mean LH concentration by decreasing the number and amplitude of LH pulses and the basal LH values in two cows, although the decrease in one was not significant. The mean LH concentration in each cow remained unaffected by the combined treatment of morphine and naloxone. In conclusion, the elevation of LH concentration by naloxone, the suppression of LH release by morphine and the reversal by morphine and naloxone of each other's effects suggest that EOP could be involved in the control of LH release in cows in the absence of ovarian influence.

Development of an endocrine challenge test to investigate subfertility in ewes

Simultaneous or sequential injection of 250 ng gonadotrophin releasing hormone (GnRH) and 25 μg oestradiol benzoate, with luteinizing hormone (LH) measurements at 0, +20 min (after GnRH) and +16 h (after oestradiol), enabled investigation of the positive feedback effects on the hypothalamus and pituitary. Control ewes had pretreatment LH values of 3·1 ± 1·2 ng/ml with an increment of 3·2 ± 2·3 ng/ml 20 min after GnRH. Subfertile ewes, in spite of elevated pretreatment LH concentrations (15·8 ± 9·5 ng/ml) in eight out of 10 ewes, had increments of 1·4–84 ng/ml after GnRH. Control ewes had LH increments of 3–75 ng/ml 16 h after oestradiol. Subfertile ewes with pretreatment LH concentrations < 15 ng/ml also responded to oestradiol whereas those with initial LH concentrations 16–40 ng/ml had no further LH increment. Subsequent administration of 1000 iu pregnant mares' serum gonadotrophin (PMSG), with measurement of LH and oestradiol at 0, +24, +30, +48, +54, and +72 h, allowed assessment of ovarian response and hypothalamus-pituitary function. Five control ewes were sampled up to 30 h post-PMSG and only 1 had oestradiol concentrations > 10 pg/ml. Sampling up to 72 h in another five control ewes resulted in oestradiol concentrations > 10 pg/ml. Increments in LH concentration > 3 ng/ml were recorded in control and subfertile ewes with oestradiol concentrations > 10 pg/ml. The use of these endocrine challenge tests enabled positive diagnosis of abnormality on 8 out of 10 occasions. Post-mortem examination of seven of the subfertile ewes revealed reproductive tract abnormalities characterized by very small inactive ovaries, and in four cases complete absence of oviducts, uterus, cervix and anterior vagina (although these latter abnormalities could not have been diagnosed from the tests described).

Homosexual and social behaviours of young bulls of different geno- and phenotypes and plasma concentrations of some hormones

Homosexual mounting and social interactions of young bulls were observed, and plasma concentrations of testosterone, oestradiol 17β, progesterone and luteinizing hormone (LH) were determined. The observations were conducted on 12 Black and White (BW), 9 Hereford (HER) and 12 hybrid bulls (HYB) with 25% European bison blood. Among the bulls, there were individuals with body conformation classified subjectively as typical of males or more typical of females. In the first period, the bulls were kept in separate genotype groups in pens and during the second period all genotype groups were kept together on a pasture. The frequency of initiated mounts and social interactions was the highest in BW bulls and the lowest in HYB bulls. The frequency of performed and received “flehmen” was the highest in HER bulls, whereas the frequency of received “flehmen” was the lowest in BW bulls. The bulls of the male-type body conformation initiated fewer and received more mounts, as well as initiated and received more butts than those of the female-type body conformation. HER group mates were preferred as partners for mounting by bulls of all genotypes. For aggressive interactions, bulls of all genotypes preferred partners of their own genotype. HER bulls and bulls of the male-type body conformation had a higher mean dominance index. The highest level of testosterone and LH, and the lowest level of progesterone, were found in HER bulls. The highest level of progesterone and the lowest level of oestradiol 17β were found in HYB bulls, whereas the highest level of oestradiol 17β was found in BW bulls. Bulls of the male-type body conformation showed a slightly higher level of all hormones except for the median value of LH. The rank-correlation coefficients between the behavioural traits and hormone concentrations were rather low to medium sized and variable in particular genotype groups.

Prospective Hormone Study of Hypothalamic-Pituitary Function in Patients with Nasopharyngeal Carcinoma after High Dose Irradiation

With the aim of evaluating the effect of high dose irradiation (6,500 cGy/36 fractions or higher) to pituitary fossa, a prospective study was carried out in patients with nasopharyngeal cancer by a serial determination of several hormones in the serum, before and after the course of radiation therapy (RT). The radiation treatment field was at least 1 cm above the skull base with bilateral parallel opposing fields. Hormone assays were performed three times on each patient: (1) prior to, (2) one month after, (3) 15-18 months after radiation therapy. The study included determination of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), cortisol, growth hormone (GH) and prolactin concentrations and LH-releasing hormone, thyrotrophin-releasing hormone stimulation and insulin tolerance tests were also carried out. Complete profiles were obtained in 24 patients (16 males and 8 females), aged 16-67 years. The results showed a significant decrease in the level of serum peak value of LH in males 18 months after therapy, and also in GH both one month and 18 months after therapy. A significant increase in the peak value of serum TSH observed after therapy. Decreased serum FSH, cortisol and prolactin levels were noted, but these did not reach statistical significance. The decrease in GH level appeared earlier and was more sensitive than that found for the other hormones, and could prove to be a useful parameter for clinical evaluation. None of the patients showed any clinically recognizable symptoms or signs of hormone deficiency in the 18-33 months following completion of the radiation therapy.