Serum TSH and total T4 in the United States population and their association with participant characteristics: National Health and Nutrition Examination Survey (NHANES 1999-2002).
OBJECTIVE
Describe thyrotropin (TSH) and thyroxine (T4) levels in the U.S. population and their association with selected participant characteristics.


METHODS
Secondary analysis of data from the National Health and Nutrition Examination Survey (NHANES) collected from 4392 participants, reflecting 222 million individuals, during 1999-2002.


RESULTS
Hypothyroidism prevalence (TSH > 4.5 mIU/L) in the general population was 3.7%, and hyperthyroidism prevalence (TSH < 0.1 mIU/L) was 0.5%. Among women of reproductive age (12-49 years), hypothyroidism prevalence was 3.1%. Individuals aged 80 years and older had five times greater odds for hypothyroidism compared to 12- to 49-year-olds (adjusted odds ratio [OR] = 5.0, p = 0.0002). ORs were adjusted for sex, race, annual income, pregnancy status, and usage of thyroid-related medications (levothyroxine/thyroid, estrogen, androgen, lithium, and amiodarone). Compared to non-Hispanic whites, non-Hispanic blacks had a lower risk for hypothyroidism (OR = 0.46, p = 0.04) and a higher risk for hyperthyroidism (OR = 3.18, p = 0.0005), while Mexican Americans had the same risk as non-Hispanic whites for hypothyroidism, but a higher risk for hyperthyroidism (OR = 1.98, p = 0.04). Among those taking levothyroxine or desiccated thyroid, the adjusted risk for either hypothyroidism (OR = 4.0, p = 0.0001) or hyperthyroidism (OR = 11.4, p = 4 x 10(-9)) was elevated.


CONCLUSIONS
Associations with known factors such as age, race, and sex were confirmed using this data set. Understanding the prevalence of abnormal thyroid tests among reproductive-aged women informs decisions about screening in this population. The finding that individuals on thyroid hormone replacement medication often remain hypothyroid or become hyperthyroid underscores the importance of monitoring.
Aoki
Yutaka
Y
Association of Schools of Public Health, Washington, DC, USA.
Belin
Ruth M
RM
Clickner
Robert
R
Jeffries
Rebecca
R
Phillips
Linda
L
Mahaffey
Kathryn R
KR
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology; D007037:Hypothyroidism / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D011247:Pregnancy; D015995:Prevalence; D044469:Racial Groups; D012307:Risk Factors; D012494:Sampling Studies; D012727:Sex Characteristics; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014481:United States / Q000453:epidemiology
D013972:Thyrotropin; D013974:Thyroxine