DIE ENSIMATIESE BEPALING VAN DIE T OTALE PURIENE IN URINE BY P ERSONE MET AANGEBORE METABOLIESE DEFEKT E

Abstract

In this study an attempt was made to establish a screening method for the enzymatic determination of total purines in the urine of control persons and persons with relevant deficiencies in order to determine whether a person has a defect in his or her purine metabolism or not. From the literature a method was obtained where the total amount of purines could be determined in one single analysis. This method was further investigated in the research and standardised for use in urine. Urine samples of control persons and persons with adenosine deaminase deficiency, adenylosuccinase deficiency, Lesch-Nyhan syndrome, molybdenum co-factor deficiency, purine nucleoside phosphorylase deficiency, OCT deficiency and xanthinuria were used. By determining the purine content of this urine, purine nucleoside phosphorylase deficiency and molybdenum co-factor deficiency could be identified as abnormal. On the other hand, by determining the uric acid content of this urine, xanthinuria and molybdenum co-factor deficiency could be identified as abnormal. Alternatively, the relationship between the purine content and the uric acid content of urine samples was determined and compared with the control values. In this way molybdenum co-factor deficiency, purine nucleoside phosphorylase deficiency and xanthinuria, as well as a single urine sample for each of the adenylosuccinase deficiency, LeschNyhan syndrome and OCT deficiency, were identified as abnormal. The difference between the values and control values of these defects was more obvious than when using purine content or uric acid content alone. The method used in the research can therefore be used as a screening method, but only for the first three defects mentioned and individuals of the defects mentioned last. This method is relatively inexpensive, because the combined cost of determining purine content and uric acid content of one urine sample amounts to Rl 70. Except in cases where high consentrations of guanosine occur which is broken down slowly because of the relative high cost of guanase and the fact that the increase of the enzyme concentration would not be cost-effective, the analyses also take relatively little time. To determine the purine content of an urine sample takes a maximum of forty-five minutes and to determine the uric acid content takes a maximum of twenty minutes. A disadvantage of this method is the long preparation time - approximately seventy-five minutes - before the purine content can be determined. During the study it was further found that the determination of the purine content was sensitive to small variations in the purine concentration, while the determination of the uric acid content was not sensitive to small variations in the uric acid consentration. The possibility to automatise investigated, but because the varied too much, the method fully. By using the Bechman the method was semi-automatised 2 the time could DU-7500 in its method was also that analyses took not be automatised spectrophotometer, current form.