NHANES III measured serum TSH, total serum T(4), antithyroperoxidase (TPOAb), and antithyroglobulin (TgAb) antibodies from a sample of 17,353 people aged > or =12 yr representing the geographic and ethnic distribution of the U.S. population. These data provide a reference for other studies of these analytes in the U.S. For the 16,533 people who did not report thyroid disease, goiter, or taking thyroid medications (disease-free population), we determined mean concentrations of TSH, T(4), TgAb, and TPOAb. A reference population of 13,344 people was selected from the disease-free population by excluding, in addition, those who were pregnant, taking androgens or estrogens, who had thyroid antibodies, or biochemical hypothyroidism or hyperthyroidism. The influence of demographics on TSH, T(4), and antibodies was examined. Hypothyroidism was found in 4.6% of the U.S. population (0.3% clinical and 4.3% subclinical) and hyperthyroidism in 1.3% (0.5% clinical and 0.7% subclinical). (Subclinical hypothyroidism is used in this paper to mean mild hypothyroidism, the term now preferred by the American Thyroid Association for the laboratory findings described.) For the disease-free population, mean serum TSH was 1.50 (95% confidence interval, 1.46-1.54) mIU/liter, was higher in females than males, and higher in white non-Hispanics (whites) [1.57 (1.52-1.62) mIU/liter] than black non-Hispanics (blacks) [1.18 (1.14-1.21) mIU/liter] (P < 0.001) or Mexican Americans [1.43 (1.40-1.46) mIU/liter] (P < 0.001). TgAb were positive in 10.4 +/- 0.5% and TPOAb, in 11.3 +/- 0.4%; positive antibodies were more prevalent in women than men, increased with age, and TPOAb were less prevalent in blacks (4.5 +/- 0.3%) than in whites (12.3 +/- 0.5%) (P < 0.001). TPOAb were significantly associated with hypo or hyperthyroidism, but TgAb were not. Using the reference population, geometric mean TSH was 1.40 +/- 0.02 mIU/liter and increased with age, and was significantly lower in blacks (1.18 +/- 0.02 mIU/liter) than whites (1.45 +/- 0.02 mIU/liter) (P < 0.001) and Mexican Americans (1.37 +/- 0.02 mIU/liter) (P < 0.001). Arithmetic mean total T(4) was 112.3 +/- 0.7 nmol/liter in the disease-free population and was consistently higher among Mexican Americans in all populations. In the reference population, mean total T(4) in Mexican Americans was (116.3 +/- 0.7 nmol/liter), significantly higher than whites (110.0 +/- 0.8 nmol/liter) or blacks (109.4 +/- 0.8 nmol/liter) (P < 0.0001). The difference persisted in all age groups. In summary, TSH and the prevalence of antithyroid antibodies are greater in females, increase with age, and are greater in whites and Mexican Americans than in blacks. TgAb alone in the absence of TPOAb is not significantly associated with thyroid disease. The lower prevalence of thyroid antibodies and lower TSH concentrations in blacks need more research to relate these findings to clinical status. A large proportion of the U.S. population unknowingly have laboratory evidence of thyroid disease, which supports the usefulness of screening for early detection.

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Serum TSH, T4, and Thyroid Antibodies in the United States Population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III)

Summary
BACKGROUND AND OBJECTIVE The original Whlckham Survey documented the prevalence of thyroid disorders in a randomly selected sample of 2779 adults which matched the population of Great Britain in age, sex and social class. The aim of the twenty-year follow-up survey was to determine the Incidence and natural history of thyroid disease in this cohort.

DESIGN, PATIENTS AND MEASUREMENTS Subjects were traced at follow-up via the Electoral Register, General Practice registers, Gateshead Family Health Services Authority register and Office of Population Censuses and Surveys. Eight hundred and twenty-five subjects (30% of the sample) had died and, In addition to death certificates, two-thirds had Information from either hospital/General Practitioner notes or post-mortem reports to document morbidity prior to death. Of the 1877 known survivors, 96% participated in the follow-up study and 91 % were tested for clinical, biochemical and Immunological evidence of thyroid dysfunction.

RESULTS Outcomes in terms of morbidity and mortality were determined for over 97% of the original sample. The mean Incidence (with 95% confidence Intervals) of spontaneous hypothyroidism in women was 3.5/1000 survivors/year (2.8-4.5) rising to 4.1/1000 survivors/year (3.3-5.0) for all causes of hypothyroidism and in men was 0.6/1000 survivors/year (0.3-1.2). The mean incidence of hyperthyroidism In women was 0.8/1000 survivors/year (0.5.1.4) and was negligible in men. Similar incidence rates were calculated for the deceased subjects. An estimate of the probability of the development of hypothyroidism and hyperthyroidism at a particular time, i.e. the hazard rate, showed an Increase with age In hypothyroidism but no age relation in hyperthyroidism.

The frequency of goitre decreased with age with 10% of women and 2% of men having a goitre at follow-up, as compared to 23% and 5% in the same subjects respectively at the first survey. The presence of a goitre at either survey was not associated with any clinical or biochemical evidence of thyroid dysfunction. In women, an association was found between the development of a goitre and thyroid-antibody status at follow-up, but not initially.

The risk of having developed hypothyroidism at follow-up was examined with respect to risk factors Identified at first survey. The odds ratios (with 95% confidence Intervals) of developing hypothyroidism with (a) raised serum TSH alone were 8 (3-20) for women and 44 (19-104) for men; (b) positive anti-thyroid antibodies alone were 8 (5-15) for women and 25 (10-63) for men; (c) both raised serum TSH and positive anti-thyroid antibodies were 38 (22-65) for women and 173 (81-370) for men. A loglt model Indicated that Increasing values of serum TSH above 2mU/l at first survey Increased the probability of developing hypothyroidism which was further Increased in the presence of anti-thyroid antibodies. Neither a positive family history of any form of thyroid disease nor parity of women at first survey was associated with Increased risk of developing hypothyroidism. Fasting cholesterol and triglyceride levels at first survey when corrected for age showed no association with the development of hypothyroidism In women.

CONCLUSIONS This historical cohort study has provided Incidence data for thyroid disease over a twenty-year period for a representative cross-sectional sample of the population, and has allowed the determination of the importance of prognostic risk factors for thyroid disease Identified twenty years earlier.

/pdf/the-incidence-of-thyroid-disorders-in-the-community-a-twenty-26md1r21cb.pdf

The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham Survey

In 1912, Hashimoto described four women in whom the thyroid gland was enlarged and appeared to have been transformed into lymphoid tissue (“struma lymphomatosa”).1 Although the patients were not initially hypothyroid, they became so after thyroid surgery. Over 40 years later, the presence of antithyroid antibodies was reported in patients with this disorder.2 Hashimoto's disease, or Hashimoto's thyroiditis, is now recognized as a form of chronic autoimmune thyroiditis. There is no internationally accepted classification of autoimmune thyroid diseases.3 Some investigators consider autoimmune thyroiditis a histologic diagnosis that can be subdivided into lymphocytic thyroiditis, if only lymphocytic infiltration is present, and . . .

Chronic Autoimmune Thyroiditis

This work consists of two volumes, and extends over eighteen hundred closely printed pages. In the preface we are informed that the greater part was in manuscript when the pen dropped from the author's hand. The section on Diseases of the Heart was not completed, and that on Diseases of the Skin was not commenced. Dr Wilks has completed the former; while the editor, Dr Pye-Smith, has supplied the latter. The range of the work is the same as that of other treatises on the Principles and Practice of Medicine, while owing to its size greater freedom has necessarily been obtained for a more elaborate treatment of the varied subjects with which such a work deals, than could be possible in one of more restricted dimensions. But this is one of the few large works which one would gladly have had even fuller; its whole contents are of such a quality that curtailment in any section would have been a loss. It is quite impossible in the space at our disposal to critically review the special teaching of the various chapters, and yet without this there is difficulty in conveying anything like an accurate impression of what the book is. Even to class it as the best work

The Principles and Practice of Medicine

Increasing use of assays for TSH with improved sensitivity as a first-line test of thyroid function has raised questions regarding prevalence and clinical significance of abnormal results, especially values below normal. We have assessed the thyroid status of 1210 patients aged over 60 registered with a single general practice by measurement of serum TSH using a sensitive assay. High TSH values were more common in females (11.6%) than males (2.9%). TSH values below normal were present in 6.3% of females and 5.5% of males, with values below the limit of detection of the assay present in 1.5% of females and 1.4% of males. Anti-thyroid antibodies were found in 60% of those with high TSH but only 5.6% of those with subnormal TSH. Eighteen patients were hypothyroid (high TSH, low free thyroxine) and one thyrotoxic (low TSH, raised free thyroxine) at initial testing. Seventy-three patients with elevated TSH but normal free T4 were followed for 12 months; 13 (17.8%) developed low free T4 levels and commenced thyroxine, TSH returned to normal in four (5.5%) and 56 (76.7%) continued to have high TSH values. Sixty-six patients with TSH results below normal were followed. Of the 50 subjects with low but detectable TSH at initial testing, 38 (76%) returned to normal at 12 months; of those 16 with undetectable TSH followed, 14 (87.5%) remained low at 12 months. Only one subject (who had an undetectable TSH) developed thyrotoxicosis. In view of the marked prevalence of thyroid dysfunction in the elderly, we suggest that screening of all patients over 60 should be considered.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and follow-up of abnormal thyrotrophin (TSH) concentrations in the elderly in the United Kingdom

One hundred and sixty-three asymptomatic people with thyroid antibodies or raised serum thyrotrophin (TSH) concentrations, or both, and 209 age-matched and sex-matched controls without either marker of thyroid disorder were followed up for four years to determine the natural history of autoimmune thyroiditis. Mildly raised TSH concentrations alone and the presence of thyroid antibodies alone did not significantly increase the risk of developing overt hypothyroidism during the four years compared with the controls. Overt hypothyroidism developed at the rate of 5% a year in women who initially had both raised TSH concentrations and thyroid antibodies. Prophylactic treatment with thyroxine may be justified in women found to have both markers of impending thyroid failure. The cost effectiveness of screening the adult population remains to be evaluated.

https://www.bmj.com/content/bmj/282/6260/258.full.pdf

Natural history of autoimmune thyroiditis.

Twenty-two subjects with hypothyroidism have been studied in detail before and during replacement therapy with L-thyroxine (T-4). All subjects were stabilized on the minimum dose of T-4 which was necessary to suppress their serum thyroid-stimulating hormone (TSH) concentration to normal, and on this dose most subjects had a normal or impaired TSH response to thyrotrophin-releasing hormone (TRH). The daily dose of T-4 required to suppress TSH was 0·1 mg (13 subjects), 0·15 mg (six subjects), and 0·2 mg (three subjects). It was shown that all subjects were euthyroid on these doses and, using a range of thyroid function tests, that they were normal in all respects when compared with a group of euthyroid controls, with the exception of a small group who had a marginally raised serum triiodo-L-thyronine (T-3) concentration. It has been shown that those subjects who required the larger doses of T-4 had a more advanced degree of thyroid failure than those who were stabilized on 0·1 mg T-4 daily. It is concluded that conventional doses of T-4 (0·2-0·4 mg daily) are often associated with subclinical hyperthyroidism.

https://www.bmj.com/content/bmj/3/5872/131.full.pdf

P. A. Smith

Papers

Natural history of autoimmune thyroiditis.

Treatment of hypothyroidism: a reappraisal of thyroxine therapy.

A study of the parents of patients with congenital adrenal hyperplasia: detection of the heterozygote.