Iron status, menarche, and calcium supplementation in adolescent girls.

The effects of growth, menstrual status, and calcium supplementation on iron status were studied over 4 y in 354 girls in pubertal stage 2 who were premenarcheal at baseline (x+/-SD age: 10.8+/-0.8 y).

Leptin is inversely related to age at menarche in human females.

Over the last century there has been a trend toward an earlier onset of menarche attributed to better nutrition and body fatness. With the discovery of the obesity gene and its product, leptin, we reexamined this hypothesis from a new perspective. As delayed menarche and leanness are considered risk factors for osteoporosis, we also evaluated the relation between leptin and bone mass.

Calcitriol and bone mass accumulation in females during puberty.

Adolescence is characterized by rapid skeletal development and high demands for bone minerals. Though the stimulative effect of calcitriol on intestinal calcium and phosphorus absorption is well understood, its effect on bone development is not completely clear. It may be directly involved in the facilitation of calcium economy during this critical phase of skeletal development.

Gain in body fat is inversely related to the nocturnal rise in serum leptin level in young females.

Both genetic and environmental factors contribute to adolescent obesity. Evidence of a genetic basis for obesity development is substantial, although the exact mechanism of action has yet to be identified. The purpose of this study was to document the circadian rhythmicity of the serum leptin level in young females and to assess the impact of the change in body fat stores during growth on the nocturnal rise in the serum leptin level with implications for obesity traits.