Specimen

Serum or Plasma

Collection Medium:

Alternate
Collection Media:

Green top tube (Na Heparin), Light Green top tube (Lithium Heparin)

Minimum:

Adult preferred minimum:  1 ml serum or plasma
Adult absolute minimum: 0.3 mL serum or plasma
Pediatric Minimum: 0.2 mL serum or plasma

Delivery Instructions:

Wrap specimen in aluminum foil to protect from light.  
Deliver to laboratory immediately after collection.

Analytic Time:

4 days

Reference Range:

 0-1 month         0.18 - 0.50 mg/L
 2 months-12 years 0.20 - 0.50 mg/L
 13-17 years       0.26 - 0.70 mg/L
 18+ years         0.30 - 1.2 mg/L
Retinyl Palmitate     0 - 0.10 mg/L

Comments:

Draw sample following an overnight (12 hour fast).  Patient should not 
consume alcohol for one day prior to blood draw.

Analysis includes Retinol and Retinyl Palmitate.  This assay does not 
measure other Vitamin A metabolites such as retinaldehyde and retinoic 
acid.

Serum retinol is typically maintained until hepatic stores are almost 
depleted.  Values > 0.30 mg/L probably represent adequate liver stores, 
whereas values < 0.10 mg/L indicate deficiency.  Vitamin A toxicity 
occurs when retinol exceeds the capacity of retinol binding protein 
(RBP).  Individuals with compromised renal function can retain RBP and 
may, therefore, have moderate retinol elevations.

Drugs which interfere with Vitamin A analysis include probucol 
(Lorelco).

Test
Limitations:

Samples which come in contact with plastic tubing or have been exposed 
to excessive light may show low results.

Methodology:

High Performance Liquid Chromatography

CPT Code:

84590

See Additional Information:
Fasting Specimen Requirements
Specimens Requiring Immediate Delivery