Assessment of the effects of urine matrix constituents and preservatives on the measurement of iodine

Aim: The aim of this study was to determine the effects of different chemical preservatives such as hydrochloric acid, acetic acid, boric acid, Na2CO3, sodium fluoride, formalin, thymol, ethanol+polyethylene glycol on urinary iodine measurement in vitro. Material and Method: Taking into consideration the amounts obtained from the reference studies, urine samples were transferred to each tube prepared for different preservative chemicals, with a final volume of 10 mL from the urine pool. Iodine analyzes were repeated at least five times in each tube and basal urine samples appropriate to these tubes. Results: The interferences of the urine iodine analysis results in the chemical preservatives used were 1% (v/v) 100 g/L thymol, 0.5% (w/v) Na2CO3, 1% (w/v) Na2CO3, 1% (v/v) 6N HCl, 0.25% (v/v) 100 g/L thymol, 1% (v/v) 50% acetic acide, 1% (w/v) boric acid, 1.8% (w/v) boric acid and 10 mL/L formalin with 0.15 mol/L NaCl, respectively. In addition, while the parameters which have the effects of basal pathological urine levels on iodine analysis at acceptable levels were protein and leukocyte counts, the parameters which have the effects of 1:2 of diluted samples at acceptable levels were glucose, bilirubin, urobilinogen, ketone (acetoacetic acid), erythrocyte counts and epithelial counts. However, the effects of both basal and 1:2 dilution levels of the urine sample, which had significant levels of nitrite, leukocyte and bacteria, on iodine analysis were not acceptable. Conclusion: Considering the lack of scientific data in the literature for the types and levels of preservative chemicals that can be used in urinary iodine analyzes and the protective chemical knowledge suggested in the test guides of different manufacturers, the results of this study will contribute to the determination of suitable preservatives for iodine analysis in routine laboratory applications.