A simple micro-photometric method for urinary iodine determination

作者：Grimm Gabriele^*; Lindorfer Heidelinde; Kieweg Heidi; Marculescu Rodrig; Hoffmann Martha; Gessl Alois; Sager Manfred; Bieglmayer Christian

来源：Clinical Chemistry and Laboratory Medicine, 2011, 49(10): 1749-1751.

DOI：10.1515/CCLM.2011.653

• ammonium persulfate
• photometry
• thermal cycler
• urine iodine

Background: Urinary iodide concentration (UIC) is useful to evaluate nutritional iodine status. In clinical settings UIC helps to exclude blocking of the thyroid gland by excessive endogenous iodine, if diagnostic or therapeutic administration of radio-iodine is indicated. Therefore, this study established a simple test for the measurement of UIC.
Methods: UIC was analyzed in urine samples of 200 patients. Samples were pre-treated at 95 degrees C for 45 min with ammonium persulfate in a thermal cycler, followed by a photometric Sandell-Kolthoff reaction (SK) carried out in microtiter plates. For method comparison, UIC was analyzed in 30 samples by inductivity coupled plasma mass spectrometry (ICP-MS) as a reference method.
Results: Incubation conditions were optimized concerning recovery. The photometric test correlated well to the reference method (SK=0.91*ICP-MS+1, r=0.962) and presented with a functional sensitivity of 20 mu g/L. UIC of patient samples ranged from <20 to 750 mu g/L (median 110 mu g/L); 90% of the urine samples had iodide concentrations below 210 mu g/L.
Conclusion: The modified SK-test takes approximately 90 min for analyses of 20 urine samples compared with 27 h for ICP-MS. The photometric test provides satisfactory results and can be performed with the basic equipment of a clinical laboratory.

• 出版日期2011-10