Vitamin D deficiency does still occur. Breastfed children of multiparous mothers, with increased skin pigmentation, living in the higher latitudes are at increased risk and would benefit from vitamin D supplementation while breastfeeding.

To assess further the relationship between gonadal sex steroids and PRL, GH, and insulin-like growth factor-I (IGF-I) secretion and to help clarify the mechanism underlying the pubertal growth spurt, we studied 11 children (10 girls) with central precocious puberty before and during gonadal suppression with the GnRH agonist (GnRH-a) leuprolide acetate. Nocturnal sampling for plasma levels of GH and PRL, GH response to GH-releasing factor-(1-44), and plasma IGF-I levels were determined before and 3-6 months after pituitary-gonadal suppression. Treatment caused a significant decrease in the LH and FSH responses to GnRH (P less than 0.01) and the plasma concentration of estradiol (P less than 0.05). The patients' mean height velocity SD score for chronological age, initially 3.8 +/- 1.9, decreased significantly to 0.9 +/- 0.9 with treatment (P less than 0.005). Nocturnal GH secretion (mean GH concentration, sum of GH pulse areas, sum of GH pulse amplitudes, and GH pulse frequency) and mean IGF-I levels (1.38 +/- 0.6 vs. 1.72 +/- 0.34 U/mL) were not significantly altered by treatment. However, the mean peak GH response to GH-releasing factor-(1-44) was 29.2 +/- 6.8 micrograms/L before treatment and declined significantly to 17.7 +/- 3.4 micrograms/L after gonadal suppression (P less than 0.05). PRL secretion was similar before and after GnRH-a-induced suppression. These results indicate that the decrease in height velocity noted during GnRH-a treatment occurred independently of changes in nocturnal GH secretion and IGF-I levels. These data are consistent with the premise that sex steroids can modulate growth by a direct action on skeletal growth.

We report higher serum free prolactin concentrations in women with RA compared with control subjects. This result indicates that the higher serum total prolactin levels in patients with RA are the consequence of increased free prolactin concentrations and are not due to macroprolactin.