Vitamin D

Vitamin D plays a key role in calcium and phosphate homeostasis, bone health, and muscle function. The most reliable marker of vitamin D status is serum 25-hydroxyvitamin D [25(OH)D], which reflects both dietary intake and sunlight-derived vitamin D.

Deficiency in vitamin D can lead to bone disorders such as rickets in children and osteomalacia in adults, and is also associated with increased risk of falls, muscle weakness, and fractures.