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Cholecalciferol, vitamin D 1,25-dihydroxy.

Common Use:
To assess vitamin D levels toward diagnosing disorders such as vitamin toxicity, malabsorption, and vitamin deficiency.

Serum collected in a red-top tube. Plasma collected in a green-top (heparin) tube is also acceptable.

Normal Findings:
(Method: High-performance liquid chromatography)

FormConventional UnitsSI Units (Conventional Units × 2.496)
Vitamin D 25-hydroxy
DeficientLess than 20 ng/mLLess than 49.9 nmol/L
Insufficient20–30 ng/mL49.9–74.9 nmol/L
Optimal30–100 ng/mL74.9–249.6 nmol/L
Possible ToxicityGreater than 150 ng/mLGreater than 374.4 nmol/L
Conventional UnitsSI Units (Conventional Units × 2.6)
Vitamin D 1,25-dihydroxy18–72 pg/mL47–187 pmol/L

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