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De:
Luiz Meira <luizmeira@a...>
Data: Dom Nov 7, 1999 4:41
am
Assunto: [luizmeira] Vitamina A - dosagem
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12.01.01 Vitamin A Relative Dose Response
Overview:
Results of the relative dose response, in the absence of malabsorption
or with intravenous dosing, correlate with vitamin A stores and with
dark adaption.
Dose given: retinyl palmitate, either 1 mg as water miscible solution
IV over 30 minutes or 0.45 mg in corn oil given po.
relative dose response, as percentage =
= 100% ( 1 - ((plasma vitamin A prior to dose) / (plasma vitamin A 5
hrs after dose)))
where:
• vitamin A is expressed in µg/dL in conventional units (µmol/L for
SIU)
Interpretation:
• normal is < 10%
• values > 15% indicate depleted liver vitamin A stores
• decreased levels seen with: malabsorption, cirrhosis, chronic
cholestasis, hepatocellular disease, protein-caloric malnutrition,
zinc deficiency
References:
Mobarhan S, Russell RM, et al. Evaluation of the relative dose
response test for vitamin A nutriture in cirrhotics. Am J Clin Nutri.
1981; 34:2264-2270.
Russell RM, et al. Protein-Energy Malnutrition and Liver Dysfunction
Limit the Usefulness of the Relative Dose Response (RDR) Test for
Predicting Vitamin A Deficiency. Human Nutrition: Clinical Nutrition.
1983; 37C:361-371.
Tietz NW (editor). Clinical Guide to Laboratory Tests, Third Edition.
W.B. Saunders Co. 1995. page 634-637.
<>< Luiz Roberto Salvatori Meira
><> Equilíbrio Alimentar
http://www.geocities.com/luizmeira
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