Vitamin A (Retinol)
Vitamin A circulates primarily as retinol bound to retinol-binding protein. Across US males aged 30 to 39, the median serum retinol in NHANES 2017-2018 is 55.1 µg/dL.
Unit: µg/dL · 12 slices · age and sex · 1 source
Filed under panels: Vitamins · topics: Nutrition
Serum retinol is the standard population marker of vitamin A status in adults. Liver vitamin A stores buffer day-to-day intake, so serum retinol is relatively stable across moderate intake variation in well-nourished populations. Values shown here come from the NHANES 2017-2018 vitamins A, E, and carotenoids file (VITAEC_J).
Population Distribution
Browse by Demographic
| Age (years) | male (µg/dL) | female (µg/dL) |
|---|---|---|
| 20-29 | 33.0–77.7 (50.2) | 26.0–67.9 (43.6) |
| 30-39 | 35.7–82.0 (55.1) | 30.1–69.3 (44.7) |
| 40-49 | 36.4–82.8 (55.8) | 30.3–69.7 (44.8) |
| 50-59 | 38.0–82.7 (58.7) | 33.5–79.8 (50.0) |
| 60-69 | 36.0–88.7 (55.6) | 34.1–86.5 (54.0) |
| 70+ | 37.5–90.5 (58.4) | 37.0–86.4 (56.6) |
Frequently Asked Questions
Why is serum retinol relatively stable across the population?
The liver stores months to years of vitamin A and releases retinol to circulation under tight regulation. As long as liver stores are adequate, serum retinol changes only modestly with daily intake. This is different from water-soluble vitamins like vitamin C.
Does serum retinol reflect total vitamin A intake?
Not directly. Serum retinol is held within a narrow range by homeostatic regulation in well-nourished populations, so it does not track recent intake closely. The population distribution shown here describes where a given measurement sits among US adults; it is not a clinical reference interval.
Why is retinol shown separately from carotenoids?
Beta-carotene and other provitamin-A carotenoids are converted to retinol on demand. Their serum levels reflect dietary plant intake, not vitamin A status. NHANES reports carotenoids separately in the same file. LabNorms reports retinol because it is the standard vitamin A status marker.