Hemolysis and Reagent Purity as Factors Causing Erratic Results in the Estimation of Vitamin A and Carotene in Serum by the Bessey-Lowry Method
Margaret H. Utley, Eileen R. Brodovsky, William N. Pearson · Journal of Nutrition · 1958
Hemolysis causes a false increase in serum vitamin A values when the micro-method of Bessey and Lowry is used. An especially purified and freshly prepared kerosene-xylene mixture minimizes the false increase in vitamin A caused by hemolysis and avoids errors in the carotene measurements. An unpurified kerosene-xylene mixture permitted to stand at room temperature unprotected from light may cause as much as a 10-fold increase in the apparent vitamin A content of a hemolyzed blood sample and a definite diminution in the apparent content of carotene. In the absence of hemolysis, an aged, unpurified kerosene-xylene mixture resulted in a 4-fold increase in apparent vitamin A content but no change in the carotene level. Only freshly purified and mixed kerosenexylene should be used in the Bessey-Lowry procedure for determining serum carotene and vitamin A. Serum samples showing evidence of more than a trace of hemolysis should be discarded. The Carr-Price reaction is relatively unaffected by hemolysis and is therefore the method of choice in circumstances where sufficient blood can be obtained.