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Vitamin A

Category Biochemistry
Test background

Retinol, the dietary form of vitamin A, is a fat-soluble, antioxidant vitamin important in vision and bone growth. Vitamin A synthesis is achieved through hydrolysis of animal-derived retinyl esters to retinol and, similarly, from pro-vitamin A plant carotenoids. Vitamin A is essential for skin growth, bone formation, immune function and vision. One of the earliest signs of vitamin A deficiency is night-blindness, followed by decreased visual acuity. Excess vitamin A can be hepatotoxic and moderately-elevated chronic levels correspond to increased incidence of osteoporotic events.

Clinical Indications

Suspected toxicity/overdose Suspected deficiency

Reference range
Male 0.92-2.76 umol/L
Female 0.88-2.64 umol/L



Sample & container required SST (gold top), serum (red top) or heparin (green top) Referring laboratories see Notes for sample processing requirements
Sample volume 0.5 mL
Turnaround time 2 weeks

Usually only indicated in case of overdoses or chronic ingestion.

Freeze samples immediately after separation and protect from light.

Samples can be shipped frozen or sent by First class post