Bone

Bone development continues throughout life in order to repair fractures or to adapt to changes in lifestyle - a process referred to as bone remodeling.

As is the case for bone growth, bone remodeling is critically dependent on an adequate calcium supply, which in turn is regulated by a number of factors including calcitonin, parathyroid hormone, and Vitamin D.

As an example, a severe Vitamin D deficiency affects bone growth in children, resulting in rickets, and bone remodeling in adults, thereby causing osteomalacia.

Growth

Human Growth Hormone (HGH, somatropin) is produced by the pituitary gland and stimulates cellular growth, reproduction and regeneration, mainly through the induction of Insulin-like Growth Factor-1 (IGF-1, somatomedin C) generation in the liver.

Growth hormone deficiencies lead to growth failure in infants and children.

Laboratory tests to detect a growth hormone deficiency may include (1) HGH sampling over several hours in order to detect secretory peaks, (2) measuring HGH secretion in response to provocative stimuli, and (3) measuring IGF-1 levels at baseline and after a few days of growth hormone treatment.