Protocol - Iodine

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Protocol Name from Source:

2011-12 National Health Examination Survey (NHANES) Lab Procedures Manual


Publicly available


A urine sample is collected from the study participant in a sterile specimen container. The specimen is transported to a laboratory on ice and frozen at -20°C or colder until analysis. Urinary iodine concentrations are determined by inductively coupled plasma dynamic reaction cell mass spectroscopy (ICP-DRC-MS). The 2011-12 National Health Examination Survey (NHANES) Lab Procedures Manual for Measuring Iodine and Mercury in Urine is the source, and the full protocol is found at [link[www.cdc.gov/nchs/data/nhanes/nhanes_11_12/UIOUHG_G_met_iodine_mercury.pdf|http://www.cdc.gov/nchs/data/nhanes/nhanes_11_12/UIOUHG_G_met_iodine_mercury.pdf]]


1. Specimen Collection, Storage, and Handling Procedures; Criteria for Specimen Rejection

A. Urine specimen should be collected in a urine specimen container that is sterile and prescreened for trace iodine contamination. The optimal amount of specimen required is more than 1.8 mL, minimum volume required for analysis is about 0.8 mL.

B. Specimens should be frozen at ≤20°C until analysis. Specimen stability has been demonstrated for 1 year at -20°C.

C. The criteria for unacceptable specimens are either a low volume (<0.8 mL) or suspected contamination due to improper collection procedures or collection devices. In all cases, a second specimen should be requested.

D. Specimen characteristics that may compromise test results include contamination of urine by contact with dust, dirt, etc. from improper handling.

E. In general, urine specimens should be transported and stored at -20°C. Once received, they can be frozen at -20°C for up to 1 year until analysis. Portions of the sample that remain after analytical aliquots are withdrawn and should be refrozen at -20°C. Samples thawed and refrozen several times are not compromised.

2. Reference Ranges (Normal Values)

Element/Isotope Monitored

Reference Ranges (10th-95th Percentile, mg/L) (weighted, non-creatinine corrected NHANES 2001 & 2002 results)



Personnel and Training Required

Must complete safety training seminars prior to performing any work in laboratory.

Equipment Needs

Highly specialized equipment is necessary to perform accurate iodine measurements.


Requirement CategoryRequired
Average time of greater than 15 minutes in an unaffected individualNo
Major equipmentNo
Specialized requirements for biospecimen collectionNo
Specialized trainingYes

Mode of Administration


Life Stage:

Infant, Toddler, Child, Adolescent, Adult, Senior, All Ages, Pregnancy

Specific Instructions:

There are no special fasting or dietary restrictions for the study participants. The National Health Examination Survey (NHANES) protocol requires a preservative for the mercury assay but not the iodine assay.

Research Domain Information

Release Date:

October 1, 2015


A bioassay to assess concentration (nanograms per milliliter) of urinary Iodine.


Iodine, an essential element for thyroid function, is necessary for normal growth, development, and functioning of the brain and body. Iodine-deficiency disorders (IDDs) are well-documented global health problems affecting more than 1 billion people worldwide. Consequences of IDDs include goiter, cretinism, intellectual impairment, brain damage, mental retardation, stillbirth, spontaneous abortions, miscarriages, congenital deformities, and increased perinatal mortality.

Selection Rationale

Urine samples are easy to collect and noninvasive. This assay is used to achieve rapid and accurate identification of iodine in a urine sample. The protocol is taken from the standard procedure used by staff at the Centers for Disease Control and Prevention (CDC) National Center for Environmental Health (NCEH) for the National Health Examination Survey (NHANES).




Common Data Elements (CDE)Person Urinary Iodine Concentration Bioassay in Nanograms per Milliliter5021334CDE Browser

Process and Review

The [link[phenx.org/node/62|Expert Review Panel #1]] reviewed the measures in the Anthropometrics, Diabetes, Physical Activity and Physical Fitness, and Nutrition and Dietary Supplements domains.

Guidance from the ERP includes:

• Added a new measure

  • New Data Dictionary


Centers for Disease Control and Prevention (CDC), Division of Laboratory Sciences, National Center for Environmental Health (NCEH). National Health Examination Survey (NHANES) 2011-12 Laboratory Procedure Manual for Iodine and Mercury in Urine. Atlanta, GA: Author.

Lockitch, G., Fassett, J. D., Gerson, B., Nixon, D. E., Parsons, P. J., & Savory, J. (1997). Control of pre-analytical variation in trace element determinations; Approved guideline (NCCLS document C38-A). Wayne, PA: National Committee for Clinical Laboratory Standards.

General References

Caldwell, K., Jones, R., & Hollowell, J. (2005). Urinary iodine concentration: United States NHANES 2001-2002. Thyroid, 15(7), 687-693.

Hollowell, J. G., Staehling, N. W., Hannon, W. H., Flanders, D. W., Gunter, E. W., Maberly, G. F., . . . Jackson, R. J. (1998). Iodine nutrition in the United States. Trends and public health implications: Iodine excretion data from National Health and Nutrition Examination Surveys I and III (1971-1974 and 1988-1994). Journal of Clinical Endocrinology and Metabolism, 83(10), 3401-3408.

National Institutes of Health (NIH), Office of Dietary Supplements (ODS). Dietary supplement fact sheet: Iodine. Bethesda, MD: Author.

Protocol ID:



Export Variables
Variable NameVariable IDVariable DescriptionVersiondbGaP Mapping
PX051301_Iodine_UrineSpecimen_AgePX051301030000Is the urine specimen less than one year old?4N/A
PX051301_Iodine_Urinary_Iodine_ConcentrationPX051301040000Urinary Iodine Concentration from bioassay4N/A
PX051301_Iodine_UrineSpecimen_QualityControlPX051301010000Is there at least 0.8mL of urine specimen and were standard collection procedures followed and the proper collection devices used to acquire this specimen?4N/A
PX051301_Iodine_UrineSpecimen_StoragePX051301020000Was the urine specimen frozen at -20 degrees Celsius?4N/A