Low serum thyrotropin concentrations as a risk factor for atrial fibrillation in older persons.

BACKGROUND Low serum thyrotropin concentrations are a sensitive indicator of hyperthyroidism but can also occur in persons who have no clinical manifestations of the disorder. We studied whether low serum thyrotropin concentrations in clinically euthyroid older persons are a risk factor for subsequent atrial fibrillation. METHODS We studied 2007 persons (814 men and 1193 women) 60 years of age or older who did not have atrial fibrillation in order to determine the frequency of this arrhythmia during a 10-year follow-up period. The subjects were classified according to their serum thyrotropin concentrations: those with low values (< or = 0.1 mU per liter; 61 subjects); those with slightly low values (> 0.1 to 0.4 mU per liter; 187 subjects); those with normal values (> 0.4 to 5.0 mU per liter; 1576 subjects); and those with high values (> 5.0 mU per liter; 183 subjects). RESULTS During the 10-year follow-up period, atrial fibrillation occurred in 13 persons with low initial values for serum thyrotropin, 23 with slightly low values, 133 with normal values, and 23 with high values. The cumulative incidence of atrial fibrillation at 10 years was 28 percent among the subjects with low serum thyrotropin values (< or = 0.1 mU per liter), as compared with 11 percent among those with normal values; the age-adjusted incidence of atrial fibrillation was 28 per 1000 person-years among those with low values and 10 per 1000 person-years among those with normal values (P = 0.005). After adjustment for other known risk factors, the relative risk of atrial fibrillation in elderly subjects with low serum thyrotropin concentrations, as compared with those with normal concentrations, was 3.1 (95 percent confidence interval, 1.7 to 5.5; P < 0.001). The 10-year incidence of atrial fibrillation in the groups with slightly low and high serum thyrotropin values was not significantly different from that in the group with normal values. CONCLUSIONS Among people 60 years of age or older, a low serum thyrotropin concentration is associated with a threefold higher risk that atrial fibrillation will develop in the subsequent decade.

[1]  N. Waugh,et al.  Morbidity in patients on l‐thyroxine: a comparison of those with a normal TSH to those with a suppressed TSH , 1992, Clinical endocrinology.

[2]  D. Singer.  Randomized trials of warfarin for atrial fibrillation. , 1992, The New England journal of medicine.

[3]  J. Franklyn,et al.  Prevalence and follow‐up of abnormal thyrotrophin (TSH) concentrations in the elderly in the United Kingdom , 1991, Clinical endocrinology.

[4]  G. Daniels,et al.  The use and limitations of a chemiluminescent thyrotropin assay as a single thyroid function test in an out-patient endocrine clinic. , 1990, The Journal of clinical endocrinology and metabolism.

[5]  R. Jansson,et al.  Is a more active attitude warranted in patients with subclinical thyrotoxicosis? , 1990, Journal of internal medicine.

[6]  E. Lundgren,et al.  DECREASING INCIDENCE OF THYROTOXICOSIS IN AN ENDEMIC GOITRE INLAND AREA OF SWEDEN , 1990, Clinical endocrinology.

[7]  B. Fagerberg,et al.  Thyrotoxic atrial fibrillation: an underdiagnosed or overdiagnosed condition? , 1990, Clinical chemistry.

[8]  R. Hart,et al.  Thyrotoxicosis, atrial fibrillation, and embolism, revisited. , 1989, American heart journal.

[9]  R. Eggertsen,et al.  Screening for thyroid disease in a primary care unit with a thyroid stimulating hormone assay with a low detection limit. , 1988, BMJ.

[10]  P. Petersen,et al.  Stroke in thyrotoxicosis with atrial fibrillation. , 1988, Stroke.

[11]  M. Surks,et al.  Thyrotoxicosis in the very old. , 1986, The American journal of medicine.

[12]  D. Barker,et al.  THE GEOGRAPHICAL DISTRIBUTION OF THYROTOXICOSIS IN ENGLAND ACCORDING TO THE PRESENCE OR ABSENCE OF TSH‐RECEPTOR ANTIBODIES , 1985, Clinical endocrinology.

[13]  P. Petersen,et al.  Atrial fibrillation--a review of course and prognosis. , 2009, Acta medica Scandinavica.

[14]  K. Siddle,et al.  A HIGH SENSITIVITY IMMUNOCHEMILUMINOMETRIC ASSAY FOR HUMAN THYROTROPHIN , 1984, Clinical endocrinology.

[15]  D L McGee,et al.  Duration of atrial fibrillation and imminence of stroke: the Framingham study. , 1983, Stroke.

[16]  A. Camm,et al.  Thyrotoxic atrial fibrillation , 1982 .

[17]  J. Carr.  The child who is slow to talk , 1982 .

[18]  W. Kannel,et al.  Epidemiologic features of chronic atrial fibrillation: the Framingham study. , 1982, The New England journal of medicine.

[19]  J. Kalbfleisch,et al.  The Statistical Analysis of Failure Time Data , 1980 .

[20]  J. Staffurth,et al.  Arterial embolism in thyrotoxicosis with atrial fibrillation. , 1977, British medical journal.

[21]  J. Hershman,et al.  A sensitive and precise radioimmunoassay for human thyroid-stimulating hormone. , 1975, The Journal of clinical endocrinology and metabolism.

[22]  L. Elveback,et al.  Graves' disease in Olmsted County, Minnesota, 1935 through 1967. , 1970, Mayo Clinic proceedings.

[23]  P. White,et al.  THE ELECTROCARDIOGRAM IN THYROID DISEASE , 1918 .