Davis's Lab & Diagnostic Tests

Vitamins A, B1, B6, and C

Vitamins A, B1, B6, and C is a topic covered in the Davis's Lab & Diagnostic Tests.

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Vitamin A: retinol, carotene; vitamin B1: thiamine; vitamin B6: pyroxidine, P-5′-P, pyridoxyl-5-phosphate; vitamin C: ascorbic acid.

Common Use:
To assess vitamin deficiency or toxicity to assist in diagnosing nutritional disorders such as malabsorption; disorders that affect vision, skin, and bones; and other diseases.

Serum collected in a red-top tube each for vitamins A and C; plasma collected in a lavender-top (EDTA) tube each for vitamins B1 and B6.

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

VitaminAgeConventional UnitsSI Units
Vitamin A(Conventional Units × 0.0349)
Birth–1 yr14–52 mcg/dL0.49–1.81 micromol/L
1–6 yr20–43 mcg/dL0.7–1.5 micromol/L
7–12 yr26–49 mcg/dL0.91–1.71 micromol/L
13–19 yr26–72 mcg/dL0.91–2.51 micromol/L
Adult30–120 mcg/dL1.05–4.19 micromol/L
Vitamin B1(Conventional Units × 29.6)
Serum or plasma0.21–1 mcg/dL6.2–30 nmol/L
Whole blood2.5–7.5 mcg/dL74–222 nmol/L
Vitamin B6(Conversion Factor × 4.046)
5–30 ng/mL20–121 nmol/L
Vitamin C(Conventional Units × 56.78)
0.6–1.9 mg/dL34.1–107.9 micromol/L
Vitamin B1, vitamin B6, and vitamin C levels tend to decrease in older adults.

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