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Vitamin D (25-OH)

25-Hydroxyvitamin D 25(OH)D Calcidiol Vitamin D3
Serum (SST) nmol/L

About this test

Storage form of vitamin D; the best marker of overall vitamin D status. Formed in the liver from dietary vitamin D3 and skin UV synthesis. Deficiency leads to rickets (children) and osteomalacia (adults).

Reference Ranges

Sex Age Range Notes
All All ages > 50 Sufficient ≥50 nmol/L (≥20 ng/mL); insufficient 25–49; deficient <25; toxicity concern >250

Clinical Interpretation

Low / Decreased
Deficiency — osteomalacia, rickets, myopathy, secondary hyperparathyroidism, increased fracture risk. Associations with autoimmune disease, infections, and CVD.
High / Increased
Toxicity (>250 nmol/L) — hypercalcaemia, nephrocalcinosis.

Related Tests

Adjusted Calcium Phosphate
Specimen
Serum (SST)
Reporting Unit
nmol/L
Category
💊 Vitamins

⚠ Clinical Note
Reference ranges are indicative. Always interpret results in the context of the individual patient and local laboratory reference intervals, which may vary.