South Bend Medical Foundation - Your Community Laboratory

test directorySearch Results

Click here to search again.

Test Name:
Vitamin A (Retinol)

• SBMF No:
  23302
• Performance Lab Name:
  Manual Lab
• Test Mnemonic:
  VIT A
• ABN:
  Required – Not FDA-Approved
• CPT Code:
  84590
• LOINC Code:
  2923-1
• Also Known As:
  Retinol
• Spec Type:
  Serum
• Spec Container:
  Gold top (SST) or red top (serum) tube
• Alt Spec Type:
  Plasma
• Alt Spec Container:
  Lavender top (EDTA) tube
• Pref Vol:
  1.0 mL
• Min Vol:
  0.5 mL
• Fasting:
  Yes
• Patient Prep:
  Fasting for at least 8 hours
  Recommend abstaining from alcohol for 24 hours before specimen collection
• Spec Collect:
  Routine venipuncture
• Spec Process:
  Protect from light
  Serum sample tubes, clot 30 minutes
  All tubes, promptly centrifuge 15 minutes
  Immediately transfer serum or plasma to amber transfer tube and freeze
• Spec Store Transport:
  Frozen
  Protected from light
• Spec Stability:
  12 hours refrigerated (2-8°C) and protected from light
  1 month frozen (-20°) and protected from light – Do not use frost-free units that undergo repeated freeze/thaw cycles
• Methodology:
  High Performance Liquid Chromatography (HPLC)
• Use:
  Quantitation of circulating Vitamin A (retinol) concentration
• Clinical Significance:
  

  Vitamin A (retinol) is a fat-soluble vitamin that is required for proper vision, growth and normal tissue development. The earliest clinical manifestation of Vitamin A deficiency is vision loss in dim light (night blindness). Two sources of Vitamin A in the diet include preformed vitamin A that is most often present in the form of retinyl ester and the carotenoids (including beta-carotene). They are subject to emulsification and mixed micelle formation by the action of bile salts before being transported into the intestinal cell. The efficiency of absorption of preformed vitamin A is high at between 70–90%. Carotenoids are absorbed into the duodenal mucosal cells by passive diffusion and their absorption efficiency is much lower at between 9 to 22%. Preformed vitamin A is obtained from animal-derived foods, such as organ meats and fish oils. Other sources are full cream milk, butter and fortified margarines. The carotenoids are obtained from yellow to orange pigment fruits and vegetables and green leafy vegetables, such as pumpkin, carrots, tomatoes, apricots, grapefruit, lettuce and most green vegetables. The U.S. National Health and Nutrition Examination Survey (NHANES-II) indicated that approximately 25% of the vitamin A requirement was provided by carotenoids and about 75% by preformed retinol. Vitamin A deficiency can be seen secondary to lack of dietary preformed Vitamin D and carotenoids in malnutrition or lack of adequate intestinal absorption (malabsorption ).

  Excess of Vitamin A can lead to toxicity with nausea and vomiting, anorexia, weakness and dermatitis. Skeletal abnormalities can occur in children with Vitamin A toxicity. Ingestion of large amounts of liver (where considerable Vitamin A is stored) can lead to toxicity. Polar bear liver has toxic amounts of Vitamin A.

  Measuring the plasma concentration of vitamin A is the most convenient and widely used method to assess vitamin A status. However, it is not an ideal indicator because it does not decline until liver stores become critically depleted.

• Reference Range:
  

  Age	Reference Range
  0 - 1 month 2 months - 12 years 13 - 17 years 18 years and older	0.18 - 0.50 mg/L 0.20 - 0.50 mg/L 0.26 - 0.70 mg/L 0.30 - 1.20 mg/L

• Additional Test Info:
  This test was developed and its performance characteristics determined by South Bend Medical Foundation laboratory. It has not been cleared or approved by the U.S. Food and Drug Administration. The test is used for clinical purposes and should not be regarded as investigational or for research. SBMF is certified under CLIA as qualified to perform high complexity clinical laboratory testing.
• Day Run:
  Tue, Fri
• Test Type:
  CHEMISTRY