Cited by 2,824Thyroid Disorders and TreatmentsThyroid and Parathyroid SurgeryThyroid Cancer Diagnosis and Treatment

The Colorado Thyroid Disease Prevalence Study

Canaris, Gay J., Manowitz, Neil R., Mayor, Gilbert, Ridgway, E. Chester·2000·Archives of Internal Medicine

Abstract

CONTEXT: The prevalence of abnormal thyroid function in the United States and the significance of thyroid dysfunction remain controversial. Systemic effects of abnormal thyroid function have not been fully delineated, particularly in cases of mild thyroid failure. Also, the relationship between traditional hypothyroid symptoms and biochemical thyroid function is unclear. OBJECTIVE: To determine the prevalence of abnormal thyroid function and the relationship between (1) abnormal thyroid function and lipid levels and (2) abnormal thyroid function and symptoms using modern and sensitive thyroid tests. DESIGN: Cross-sectional study. PARTICIPANTS: Participants in a statewide health fair in Colorado, 1995 (N = 25 862). MAIN OUTCOME MEASURES: Serum thyrotropin (thyroid-stimulating hormone [TSH]) and total thyroxine (T4) concentrations, serum lipid levels, and responses to a hypothyroid symptoms questionnaire. RESULTS: The prevalence of elevated TSH levels (normal range, 0.3-5.1 mIU/L) in this population was 9.5%, and the prevalence of decreased TSH levels was 2.2%. Forty percent of patients taking thyroid medications had abnormal TSH levels. Lipid levels increased in a graded fashion as thyroid function declined. Also, the mean total cholesterol and low-density lipoprotein cholesterol levels of subjects with TSH values between 5.1 and 10 mIU/L were significantly greater than the corresponding mean lipid levels in euthyroid subjects. Symptoms were reported more often in hypothyroid vs euthyroid individuals, but individual symptom sensitivities were low. CONCLUSIONS: The prevalence of abnormal biochemical thyroid function reported here is substantial and confirms previous reports in smaller populations. Among patients taking thyroid medication, only 60% were within the normal range of TSH. Modest elevations of TSH corresponded to changes in lipid levels that may affect cardiovascular health. Individual symptoms were not very sensitive, but patients who report multiple thyroid symptoms warrant serum thyroid testing. These results confirm that thyroid dysfunction is common, may often go undetected, and may be associated with adverse health outcomes that can be avoided by serum TSH measurement.

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Crossref · 10.1001/archinte.160.4.526

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  • 25-40% of patients on long-term levothyroxine treatment have a TSH concentration below or above the reference range.

    “However, 25-40% of patients on long-term levothyroxine treatment have a TSH concentration below or above the reference range.7,9,10”

    From Hypothyroidism (2024) · cites this paper as [10]

  • The prevalence of hypothyroidism (subclinical and overt) ranges from 0.2% to 5.3% in Europe and 0.3% to 3.7% in the USA, depending on the definition used and the population.

    “The prevalence of hypothyroidism (subclinical and overt) ranges from 0•2% to 5•3% in Europe 3, 35- 37 and 0•3% to 3•7% in the USA, 10 depending on the definition used and the population.”

    From Hypothyroidism (2024) · cites this paper as [10]

  • Approximately 10-15% of patients express dissatisfaction on levothyroxine despite TSH normalisation, due to persistent, residual symptoms that might reflect ongoing hypothyroidism.

    “Approximately 10-15% of patients express dissatisfaction on levothyroxine despite TSH normalisation, due to persistent, residual symptoms that might reflect ongoing hypothyroidism.10,11”

    From Hypothyroidism (2024) · cites this paper as [10]

  • 60% of unselected euthyroid individuals have one or more symptom that may be attributable to hypothyroidism.

    “60% of unselected euthyroid individuals have one or more symptom that may be attributable to hypothyroidism. 39”
  • Patients aged 70 years or older may have fewer symptoms or signs and are less likely to exhibit some classic signs such as cold intolerance and weight gain compared with younger individuals (aged ≤55 years).

    “Patientsaged 70 years or older may have fewer symptoms or signs and are less likely to exhibit someclassicsignssuchascoldintoleranceandweight gain compared with younger individuals (aged ≤ 55 years). 41”

    From Hypothyroidism: A Review (2025) · cites this paper as [41]

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Authors
Canaris, G. J., Manowitz, N. R., Mayor, G., & Ridgway, E. C.
Affiliations
  • University of Nebraska Medical Center (US)
  • Abbott (United States) (US)
  • University of Colorado Denver (US)
Venue
Archives of Internal Medicine
Published
2000-02-28
Volume
160
Issue
4
Pages
526
ISSN
0003-9926 (ISSN-L)
OpenAlex
W2140936682
Cited by
2,824
References
50
Citations by year
2026: 49 · 2025: 64 · 2024: 86 · 2023: 138 · 2022: 158 · 2021: 151 · 2020: 191 · 2019: 147 · 2018: 148 · 2017: 166 · 2016: 161 · 2015: 140 · 2014: 144 · 2013: 147 · 2012: 132
FWCI
31.07
Type
journal article
Language
en
Open access
closed
Locations
  • Archives of Internal Medicine (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Health Sciences › Medicine › Surgery › Thyroid and Parathyroid Surgery
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Cancer Diagnosis and Treatment
Keywords
thyroid dysfunction, hypothyroidism, thyroid-stimulating hormone, thyroxine, serum lipids, cholesterol, LDL cholesterol, thyroid medication, cardiovascular risk
MeSH terms
Adult, Age Factors, Aged, Colorado, Cross-Sectional Studies, Diagnosis, Differential, Female, Humans, Lipids, Male, Middle Aged, Surveys and Questionnaires, Sex Factors, Thyroid Diseases, Thyroid Hormones, Prevalence

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