Vitamin A (retinol): what your result means.

A fat-soluble vitamin important for vision, immunity, and skin health. Vitamin A (retinol) is measured by blood test as part of the Nutritional panel in the HodieLabs Health Blueprint.

Why Vitamin A (retinol) matters

Serum retinol is homeostatically controlled. It only drops when liver stores are severely depleted. Retinol-binding protein (RBP) is a more sensitive early marker of vitamin A status.

Associated risks when out of range: Deficiency causes night blindness, immune dysfunction, and poor wound healing. Toxicity (hypervitaminosis A) causes liver damage, bone pain, and teratogenicity.

What the clinical evidence shows

The evidence base behind how the HodieLabs Evidence-Based Clinical Library interprets Vitamin A (retinol), from randomised trials, prospective cohorts and genetic (Mendelian randomisation) studies. Full citations in the reference list below.

• ATBC trial (NEJM 1994): beta-carotene supplementation increased lung cancer incidence in smokers, the seminal demonstration that more of a 'good' nutrient can harm.
• CARET trial (Omenn et al. NEJM 1996): beta-carotene plus retinol was stopped early for a 28% increase in lung cancer among high-risk participants. Why vitamin A status is measured and corrected, never blindly supplemented.

Evidence-based reference ranges

The HodieLabs Evidence-Based Clinical Library interprets Vitamin A (retinol) against published clinical authority standards, never arbitrary "optimal" ranges. Measured in µmol/L:

Clinical interpretation

• Serum retinol is homeostatically controlled. It only drops when liver stores are severely depleted.
• Retinol-binding protein (RBP) is a more sensitive early marker of vitamin A status.
• Beta-carotene supplementation is preferred over preformed vitamin A to avoid toxicity risk.

What improves it: the evidence-based levers

• Dietary optimisation
• Avoid excess supplementation

Recommended testing frequency: Annual, as part of a comprehensive panel. Single markers are always interpreted in context.

How Vitamin A (retinol) testing works at HodieLabs

Vitamin A (retinol) is measured in every Health Blueprint at our Melbourne Preventative Health & Longevity Clinic, interpreted by a doctor against the guideline-cited ranges above and tracked over time through your HodieLabs membership.

References

1. The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group. The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers (ATBC). N Engl J Med. 1994;330:1029–1035.
2. Omenn GS, et al. Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease (CARET). N Engl J Med. 1996;334:1150–1155.

This page is general information from the HodieLabs Evidence-Based Clinical Library, not medical advice. Speak with your GP about what testing and care is appropriate for you.