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)
Iodine deficiency in a population causes increased prevalence of goiter and, more importantly, may increase the risk for intellectual deficiency in that population. The National Health and Nutrition Examination Surveys [NHANES I (1971-1974) and (NHANES III (1988-1994)] measured urinary iodine (UI) concentrations. UI concentrations are an indicator of the adequacy of iodine intake for a population. The median UI concentrations in iodine-sufficient populations should be greater than 10 microg/dL, and no more than 20% of the population should have UI concentrations less than 5 microg/dL. Median UI concentrations from both NHANES I and NHANES III indicate adequate iodine intake for the overall U.S. population, but the median concentration decreased more than 50% between 1971-1974 (32.0+/-0.6 microg/dL) and 1988-1994 (14.5+/-0.3 microg/dL). Low UI concentrations (<5 microg/dL) were found in 11.7% of the 1988-1994 population, a 4.5-fold increase over the proportion in the 1971-1974 population. The percentage of people excreting low concentrations of iodine (UI, <5 microg/dL) increased in all age groups. In pregnant women, 6.7%, and in women of child-bearing age, 14.9% had UI concentrations below 5 microg/dL. The findings in 1988-1994, although not indicative of iodine deficiency in the overall U.S. population, define a trend that must be monitored.
Hollowell
J G
JG
Centers for Disease Control, National Center for Environmental Health, Division of Environmental Hazards and Health Effects, Atlanta, Georgia 30341, USA. jgh1@cdc.gov
Staehling
N W
NW
Hannon
W H
WH
Flanders
D W
DW
Gunter
E W
EW
Maberly
G F
GF
Braverman
L E
LE
Pino
S
S
Miller
D T
DT
Garbe
P L
PL
DeLozier
D M
DM
Jackson
R J
RJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D007455:Iodine / Q000378:metabolism* / Q000652:urine; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009747:Nutritional Physiological Phenomena; D009994:Osmolar Concentration; D011247:Pregnancy; D011634:Public Health / Q000639:trends; D014481:United States
D007455:Iodine