Blood pantothenic acid measurement

Plasma and urinary levels of pantothenic acid have been measured in dietary surveys as well as in controlled studies of the vitamin deficiency. One fairly recent study with human subjects involved the feeding of a pantothenic acid-free diet for 9 weeks. The urinary pantothenic acid levels (4-6 mg/day) in vitamin-sufficient subjects were roughly half that of the intake (10 mg/day). With consumption of the vitamin-free diet, urinary pantothenic acid levels gradually declined to about 0.8 mg/day over the 9-week period (Fry et ai., 1976). Both urinary and blood serum levels of pantothenate have been used to assess dietary status. Values from urinary measurements seem to be somewhat better correlated with intake of this vitamin, than blood measurements data (Berg, 1997). 

There are no convenient or reliable functional tests of pantothenic acid status, thus assessment is made by direct measurement of whole blood or urine pantothenic acid concentrations. Urine measurements are perhaps the easiest to conduct and interpret, and concentrations are closely related to dietary intake, Whole blood measurements are preferred to plasma, which contains only free pantothenic acid and is insensitive to changes in pantothenic acid intake. Concentrations of pantothenic acid in aU of the above fluids can be measured by microbiological assay, most commonly using Lactobacillus plantarum. Whole blood must first be treated with an enzyme preparation to release pantothenic acid fi om CoA. Other techniques that have been used to measure pantothenic acid in human samples include radioimmunoassay and gas chromatography, Other techniques that have been developed include gas chromatography-mass spectrometry and a stable isotope dilution assay. CoA and AGP can be measured by enzymatic methods. ... 

Pantothenic acid is measured in the blood, urine and food. Determination of blood and urinary pantothenic acid contents can be a biomarker for the evaluation of pantothenic acid status. Measurement of pantothenic acid in as many foodstuffs as possible gives important information for determining pantothenic acid status. For example, the Standard Tables of Food Composition in Japan 2010 records pantothenic acid contents for 1878 foodstuffs (Ministry of Education, Culture, Sports, Science and Technology 2010). The pantothenic acid content of a number of foodstuffs is shown in Table 20.1. 

Because pantothenic acid must be measured in food, regardless of deficiency, analytical methods have been developed through measurement in foodstuffs. These techniques have then been applied to measurement of pantothenic acid in blood and urine. In this chapter, the development of analytical methods is first reviewed before the characteristics and issues are explained for each method. 

No analytical method has been developed that will simultaneously measure the bound forms in foodstuffs, so conversion of the bound forms to the free form is required to determine pantothenic acid (Figure 20.1). Several enzyme treatments have been proposed for liberation of the bound form from foodstuffs and a mixture of alkaline phosphatase and pantetheinase extraeted from pigeon liver has been recommended (Gonthier et al. 1998a). However, endogenous enzymes contain pantothenic acid and this must be removed from the enzyme solution before use. In contrast, pantothenic acid can be determined directly in plasma and urine samples without enzyme treatment. Red blood cells contain abundant amounts of CoA and enzyme treatment is required to measure pantothenic acid levels in blood. 

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