Validation of a simple, manual urinary iodine method for estimating the prevalence of iodine-deficiency disorders, and interlaboratory comparison with other methods.

The measurement of urinary iodine in population-based surveys provides a biological indicator of the severity of iodine-deficiency disorders. We describe the steps performed to validate a simple, inexpensive, manual urinary iodine acid digestion method, and compare the results using this method with those of other urinary iodine methods. Initially, basic performance characteristics were evaluated: the average recovery of added iodine was 100.4 +/- 8.7% (mean +/- SD), within-assay precision (CV) over the assay range 0-0.95 mumol/L (0-12 micrograms/dL) was < 6%, between-assay precision over the same range was < 12%, and assay sensitivity was 0.05 mumol/L (0.6 microgram/dL). There were no apparent effects on the method by thiocyanate, a known interfering substance. In a comparison with five other methods performed in four different laboratories, samples were collected to test the method performance over a wide range of urinary iodine values (0.04-3.7 mumol/L, or 0.5-47 micrograms/dL). There was a high correlation between all methods and the interpretation of the results was consistent. We conclude that the simple, manual acid digestion method is suitable for urinary iodine analysis.

Iron deficiency anemia in children.

Even when simple iron deficiency is strongly suspected, the child with severe anemia deserves a careful and thorough work-up before treatment is begun. Many other possible causes of anemia need to be excluded. No one test specifically identifies iron deficiency, but the combined use of several tests of iron status can establish iron deficiency with certainty. Hemoglobin level, mean corpuscular volume, serum iron, total iron binding capacity, free erythrocyte porphyrin and serum ferritin are the important studies.