What is the significance of PTH in children with vitamin D deficiency?

Parathyroid hormone (PTH) plays a crucial role in calcium homeostasis, particularly in the context of vitamin D deficiency, which is quite relevant in pediatric populations. When children experience vitamin D deficiency, their bodies are unable to effectively absorb calcium from the intestinal tract. As serum calcium levels drop due to this deficiency, the parathyroid glands respond by increasing the secretion of PTH.

The role of PTH is to raise serum calcium levels. It achieves this through several mechanisms:

1. Increased Bone Resorption: PTH stimulates osteoclast activity in the bones, which leads to the release of calcium stored in the bone matrix into the bloodstream.

2. Enhanced Renal Reabsorption of Calcium: PTH promotes the reabsorption of calcium in the kidneys, preventing its excretion in urine, thus helping to conserve calcium in the body.

3. Activation of Vitamin D: PTH also aids in the conversion of inactive vitamin D to its active form in the kidneys, which further enhances intestinal absorption of calcium. Although in the setting of vitamin D deficiency, the active vitamin D synthesis might be impaired, PTH tries to compensate for the low calcium levels by promoting this conversion.

Due to these actions,