Methods for measuring iodine in urine and serum

The most important information in the determination of the status of iodine nutrition of a population comes from the measurement of the urinary excret ion of iodine. Several methods are available for measuring urinary iodine. The choice among methods depends on the intended application, the number of samples, the cost and the technical capability. Epidemiological field stud ies demand simple, rapid and cost-effective methods. Suitable for these app lications are the rapid urinary iodide test and the ammonium persulfate oxi dation method which gives comparable results to the chloric acid method wit hout having the drawbacks of being hazardous and explosive. In research stu dies however, sophisticated automated technology like the Technicon Autoana lyzer or Paired-Ion Reversed Phase HPLC are used in which the high cost of instrumentation are outweighed by the benefits of processing a large number of samples with high accuracy and minimal technician time. For determining serum inorganic iodide (SII) the HPLC assay is the method o f choice, because contaminations from the protein bound iodine fraction do not interfere with the detection process. The clinical relevance of the mea surement of SII is limited, but allows the calculation of the absolute iodi ne uptake which has great value in pathophysiologic studies.