Serum Prolactin Levels in Humans from Birth to Adult Life

Abstract

ExtractSerum prolactin (HPr) and serum growth hormone (HGH) were determined by double antibody radioimmunoassay methods. Markedly elevated levels of serum prolactin with considerable variation were observed in the neonatal period. No significant difference was observed in six matched arteriovenous cord blood samples. No sex difference was noted in the full term infants, whereas the mean value for 24 premature male infants in the 1st week of life (190 ± 17 ng/ml SEM) was significantly higher (P < 0.001) than mean values for 34 premature female infants (104 ± 10 ng/ml SEM). During the first year of life, the mean prolactin value for both boys and girls was approximately 10 ng ml. Mean prolactin levels for both male and female children, aged 2-12 years, were approximately 5 ng/ml. Mean levels for the adolescent female were not increased significantly over those for adolescent males. However, the mean prolactin level of all values determined for adult females (7.9 ± 0.40 ng/ml SEM) was significantly increased (P < 0.001) over the mean level for adult males (5.2 ± 0.55 ng/ml, SEM). Daily serum prolactin throughout the menstrual cycle in six normal female subjects was compared with daily serum HLH levels. Considerable fluctuation was evident, particularly in the luteal phase, where the mean prolactin level was observed to be statistically higher (P < 0.005) than the mean follicular phase level.Insulin hypoglycemia did not produce a significant increase in serum prolactin in 10 normal subjects, whereas arginine infusion produced a twofold increase in mean serum prolactin at 30 min with a return to basal values by 60 min. Glucagon administered intravenously did not produce any significant change in the already elevated levels of prolactin observed on days 1 and 3 of life. Serum prolactin was uniformly and completely suppressed by L-dopa in six subjects for 1-4 hr following a single oral dose of 250 mg. In normal children, the maximal increases in both prolactin and thyroid-stimulating hormone (TSH) were observed at 15-30 min after the intravenous injection of thyrotropin-releasing hormone (TRH) and values were still slightly elevated at 120 min after injection.These studies document the pattern of secretion of serm prolactin from birth to adulthood. The physiologic basis for the increased levels of serum prolactin in the neonate has not been clarified by our studies. Significantly increased levels of prolactin are observed at a time when maximum increases in neonatal breast hypertrophy are observed clinically. Significant mean differences are observed in the adult female population compared with adult males. L-Dopa acts at the hypothalamic level to alter pituitary secretion via alterations in releasing and inhibiting hypothalamic 534 Serum prolactin by radioimmunoassay 535 hormones, whereas TRH acts directly on the pituitary. Our studies indicate that responses to these agents in the prepubertal child are qualitatively similar to those in adults. The response of the neonatal hypothalamic pituitary axis to these agents r...

Laboratory Assessment of Prolactin Status

“…The basal prolactin levels seen in healthy neonates, children, and adults in this study are consistent with those previously described in smaller groups of subjects (Friesen and Hwang, 1973;Guyda and Friesen, 1973). Even in healthy individuals, however, several factors may affect prolactin status, and appropriate interpretation of a given result demands adequate reference data in relation to factors such as sex, age, circadian rhythm, pulsatility of secretion, stress, and drug ingestion (Jeffcoate, 1978).…”

Studies on the changes of serum FSH, LH and prolactin concentrations in pubertal twins.

“…Serum concentrations of FSH, LH and prolactin in our subjects, aged 12 to 15 years, were comparable to the values reported in subjects at the corresponding ages or stages of puberty (Yen and Vicic, 1970;Penny et al, 1970;Guyda and Friesen, 1973). Since the bone age has been regarded as the most reliable index of somatic maturation and also there is a high objectivity in its determination, then the use of bone age is suitable for classifying the subjects into more homogeneous groups of pubertal development.…”

“…In general, serum prolactin levels have been reported to be unchanged from childhood to adolescence in both sexes (Hwang et al, 1971;Guyda et al, 1973;Lee et al, 1974). On the other hand, serum prolactin concentrations in females were reported to show a progressive increase after adolescence, until significant mean differences were observed in adult females compared with adult males (Grumbach et al, 1972;Guyda et al, 1973;Ehara et al, 1974). In the present study, the trend of progressive increase was noted in both boys and girls with the advancement of bone ages, but the significant between-sex difference was found only at adulthood.…”

Complex Biological Pattern of Fertility Hormones in Children and Adolescents: A Study of Healthy Children from the CALIPER Cohort and Establishment of Pediatric Reference Intervals

“…Prolactin concentrations were significantly higher during the neonatal period. The surge in prolactin in the first 30 days of life has been well documented by others (24 ) and is believed to play a role in fetal breast development (25 ). The source of this surge is believed to be fetal in origin and not maternal as is often suggested (25 ).…”