Iodine, 24 Hour, Urine
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Iodine is an essential element for thyroid hormone production. The measurement of urinary iodine serves as an index of adequate dietary iodine intake.
Monitoring iodine excretion rate as an index of daily iodine replacement therapy
Correlating total body iodine load with (131)I-uptake studies in assessing thyroid function
Daily urinary output <90 mcg/specimen suggests dietary deficiency.
Values >1,000 mcg/specimen may indicate dietary excess, but more frequently suggest recent drug or contrast media exposure.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Administration of iodine-based contrast media and drugs containing iodine, such as amiodarone, will yield elevated results.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
0-15 years: not established
> or =16 years: 93-1,125 mcg/specimen
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Knudsen N, Christiansen E, Brandt-Christensen M, et al: Age- and sex-adjusted iodine/creatinine ratio. A new standard in epidemiological surveys? Evaluation of three different estimates of iodine excretion based on casual urine samples and comparison to 24 h values. Eur J Clin Nutr 2000;54:361-363
2. Liberman CS, Pino SC, Fang SL, et al: Circulating iodine concentrations during and after pregnancy. J Clin Endocrinol Metab 1998;83:3545-3549