Quantitative measurement of retinol from a dried blood spot. Performed by LC-MS/MS for accurate detection of deficiency or hypervitaminosis A.
Retinol (all-trans)
3–5 working days
This method quantifies retinol (vitamin A) from a single dried blood spot, supporting the detection of both deficiency and excess states. Retinol status has direct implications for vision, immune function, reproduction, and embryonic development.
Clinical indications include:
Vitamin A is a fat-soluble essential nutrient that exists in two principal dietary forms: preformed retinol (from animal sources) and provitamin A carotenoids such as β-carotene (from plant sources). In the body, retinol is the predominant circulating form and serves as the primary biomarker for vitamin A status.
Children worldwide affected by vitamin A deficiency (WHO estimate)
Earliest clinical sign of vitamin A deficiency (xerophthalmia)
Excess retinol intake during pregnancy is associated with birth defects
Retinol is essential for the visual cycle, where it is converted to 11-cis-retinal in photoreceptor cells. Beyond vision, it plays critical roles in immune cell differentiation, epithelial barrier integrity, and embryonic morphogenesis through its active metabolite, retinoic acid.
Deficiency is particularly prevalent in low- and middle-income countries and among populations with restricted dietary diversity. In high-income settings, deficiency is more commonly associated with malabsorption disorders, chronic liver disease, or restrictive diets. Conversely, excessive supplementation can lead to acute or chronic toxicity, making accurate quantification important for both deficiency screening and safety monitoring.
Retinol circulates bound to retinol-binding protein (RBP), and its serum concentration is homeostatically regulated until liver stores are significantly depleted. This means that circulating retinol may remain normal until deficiency is advanced, underscoring the value of precise analytical measurement.
| Marker | Range | Interpretation |
|---|---|---|
| Retinol (preformed vitamin A) | 1.05–2.80 μmol/L (30–80 μg/dL) | Optimal |
| Retinol (preformed vitamin A) | <0.70 μmol/L (<20 μg/dL) | Deficient — associated with night blindness, immune dysfunction |
| Retinol (preformed vitamin A) | 0.70–1.05 μmol/L (20–30 μg/dL) | Marginal — subclinical deficiency |
| Retinol (preformed vitamin A) | >3.50 μmol/L (>100 μg/dL) | Potentially toxic — risk of hypervitaminosis A |
Serum retinol is homeostatically regulated by the liver, so levels only drop below normal when liver stores are severely depleted. Conversely, elevated levels may indicate excess supplementation or liver dysfunction.
Vitamin A plays essential roles in vision, immune function, skin health, and cellular growth. Testing is important for:
Vitamin A status can be improved through dietary sources, but caution is needed as excess preformed vitamin A can be toxic:
Re-test after 8–12 weeks of dietary changes or supplementation. If levels are elevated, reduce supplementation and investigate liver function.
Retinol is extracted from a dried blood spot and quantified using isotope-dilution LC-MS/MS. The method employs a deuterium-labelled internal standard (retinol-d5) to correct for matrix effects and extraction variability, ensuring accurate and reproducible results.
LC-MS/MS provides superior specificity compared to traditional HPLC-UV methods, eliminating interference from carotenoids and other retinoid metabolites that can confound UV-based detection.
The DBS matrix offers a convenient, minimally invasive collection method suitable for remote sampling and postal transit. Retinol in DBS is stable at ambient temperature for several weeks when protected from light, making it well suited for population-level screening programmes.
From enquiry to results in a few simple steps — no clinic visit required.
This test is available to healthcare professionals, wellness brands, clinics, and research institutions worldwide. We currently serve partners in:
Whether you need testing services for your patients, white-label kits for your brand, or method transfer to your own laboratory — get in touch to discuss how we can work together.
This test measures retinol (vitamin A) from a dried blood spot by LC-MS/MS using isotope dilution. Retinol is the predominant circulating form of vitamin A in the body and serves as the primary biomarker for assessing vitamin A status. The method uses a deuterium-labelled internal standard (retinol-d5) to ensure accurate and reproducible results.
Both vitamin A deficiency and excess can be harmful. Deficiency impairs vision (night blindness is the earliest clinical sign), weakens immune function, and affects skin and epithelial barrier integrity. Excess vitamin A (hypervitaminosis A) can cause liver damage, bone abnormalities, and birth defects during pregnancy. Accurate quantification is important for both deficiency screening and safety monitoring during supplementation.
The test uses a simple finger-prick to collect a few drops of blood onto a dried blood spot (DBS) card. You can do this at home or in a clinic — no venous blood draw is needed. Retinol in DBS is stable at ambient temperature for several weeks when protected from light, making it well suited for remote collection and postal transit.
Results are typically delivered within 3 to 5 working days from the time your sample arrives at our laboratory. The analysis is performed by LC-MS/MS, which provides superior specificity compared to traditional HPLC-UV methods and eliminates interference from carotenoids and other retinoid metabolites.
People with fat malabsorption conditions such as Crohn's disease, coeliac disease, and cystic fibrosis are at increased risk because vitamin A is fat-soluble and requires adequate lipid absorption. Vegans may also be at risk as preformed retinol is found only in animal sources. Pregnant women and children in developing regions are particularly vulnerable, with the WHO estimating that approximately 250 million children worldwide are affected by vitamin A deficiency.
Masdiag's vitamin A test is available worldwide through our partner network. We currently serve healthcare professionals, wellness brands, and clinics in Europe, the United Kingdom, Asia, Australia, New Zealand, and the United States. Contact us to discuss testing services, white-label kits, or method transfer to your laboratory.
Whether you need testing services, method transfer, or white-label kit development — we'd love to hear from you.