Vitamin D is essential for bone strength, calcium absorption, immune function, and muscle health.

The 25-hydroxy form (25(OH)D) is the major circulating form of vitamin D and reflects total vitamin D from diet, supplements, and sunlight exposure.

Clinical uses include:

Detecting vitamin D deficiency (linked to rickets, osteoporosis, osteomalacia).

Monitoring patients with bone disorders, kidney disease, or malabsorption syndromes.

Evaluating risk of fractures and bone weakness.

Assessing effectiveness of vitamin D supplementation.

The test is performed using a blood sample.

Analyte: 25-Hydroxy Vitamin D (25(OH)D) in blood serum.

Normal Range:

Deficient: < 20 ng/mL

Insufficient: 20–29 ng/mL

Sufficient: 30–100 ng/mL

Potentially toxic: > 100 ng/mL

Low Levels: May indicate poor diet, inadequate sunlight exposure, malabsorption, kidney/liver disease.

High Levels: Usually due to excessive supplementation, can cause hypercalcemia.

Clinical Use:

Detects vitamin D deficiency or excess.

Guides supplementation and treatment.

Supports diagnosis of bone and metabolic disorders.