Overview: Vitamin A TestIntroduction: The Vitamin A Test measures vitamin A to diagnose deficiency, causing vision problems. Aligned with 2023 WHO guidelines, it uses biochemical methods for high specificity, supporting metabolic screening. This test is critical for guiding diagnosis, treatment planning, and improving outcomes in biochemistry for patients with suspected vitamin A deficiency.
Other Names: Vitamin A Assay, Retinol Test.
FDA Status: Laboratory-developed test (LDT), meeting biochemistry standards for diagnostic accuracy.
Historical Milestone: Vitamin A testing began in the 1960s with nutritional research. Biochemical methods improved in the 2000s, enhancing diagnostic precision.
Purpose: Measures vitamin A to diagnose deficiency, guides treatment, and evaluates patients with vision problems.
Test Parameters: 1. Vitamin A Level
Pretest Condition: Fasting for 10-12 hours required. Collect serum or plasma. Report history of vision problems or nutritional deficiencies.
Specimen: Serum (SST, 2-5 mL), Plasma (EDTA, 2-4 mL). Transport in a biohazard container.
Sample Stability at Room Temperature: 8 hours
Sample Stability at Refrigeration: 7 days
Sample Stability at Frozen: 6 months
Medical History: Document vision problems, night blindness, or history of nutritional deficiencies. Include current medications or dietary history.
Consent: Written consent required, detailing the tests purpose, vitamin A deficiency implications, and risks of sample collection.
Procedural Considerations: Uses high-performance liquid chromatography (HPLC) to measure vitamin A levels. Results are available in 1-2 days, supporting clinical decisions. Performed in laboratories, often for nutritional deficiency diagnosis.
Factors Affecting Result Accuracy: Improper fasting or sample hemolysis can affect results. Dietary intake may alter vitamin A levels.
Clinical Significance: Low vitamin A confirms deficiency, guiding supplementation therapy. Normal levels may require other nutritional tests.
Specialist Consultation: Consult a nutritionist or ophthalmologist for result interpretation and treatment planning.
Additional Supporting Tests: Retinol-binding protein, liver function tests, or dietary assessment to confirm vitamin A deficiency diagnosis.
Test Limitations: Non-specific for deficiency cause; clinical correlation is needed. Sample quality affects sensitivity.
References: WHO Nutrition Guidelines, 2023; Journal of Nutrition, West KP, 2022.
