Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Vitamin A (Retinol) is a fat soluble vitamin present in meat and fish (especially liver). In addition many plant carotenoids such as beta-carotene can be converted to vitmain A by an oxygenase in the gutAfter absorption in the small intestine vitamin A is transported via chylomicrons to the liver where it is either stored as retinyl estres or exported from the liver bound to retinol binding protein (RBP)As retinal, vitamin A forms an important part of the visual pigment system. It exists combined with opsin to form rhodopsin . Light causes a change in retinal from the cis to the trans conformation which results in the generation of an electrical signal. As retinoic acid vitamin A interacts with nuclear receptors to modulate gene expression. Vitmain A plays a role in embryogenesis and in modulating the immune response.Deficiency is usually due to dietary lack, malabsorption or liver disease and may lead to xerophthalmia and permanent eye damage. Blood measurements for vitamin A deficiency are limited as decreases are seen only with severe deficiency when hepatic reserves have fallen; additionally, infection depresses blood retinol, a negative acute phase response (check CRP), however, if Vitamin A <0.5umol/L, check for clinical deficiency.Vitamin A tends to bioaccumulate so care is required in the dermatological use of retinoids due tot he possibility of teratogenicity, liver disease, musculoskeletal problems, reaised intracranial pressure, hypercalcaemia and renal insufficiency.
Specimen container paediatric:
Serum (Gold/SST) orPlasma (Purple/EDTA or Green/Lithium Heparin)
Specimen container adult:
Serum (Gold/SST) orPlasma (Purple/EDTA or Green/Lithium Heparin)
Minimum volume paediatric:
1.0 mL
Minimum volume adult:
1.0 mL
Special requirements:
Protect samples from light.
Sample stability:
Stable for 6 hours unseparated.
Once separated freeze within 1 hour.
Transport requirements:
Ambient temperature.
Quality assurance:
NEQAS
Reference ranges:
Serum/plasma
| <1 year | 0 | – | 2.0 umol/L |
| 1-11 years | 1.0 | – | 2.0 umol/L |
| 11-16 years | 1.0 | – | 2.0 umol/L |
| 16-19 years | 1.0 | – | 3.0 umol/L |
| Adult | 1.05 | – | 2.8 umol/L |
Other info:
Assay performed by HPLC with UV detection