Prevalence of Various Degrees of Hypothyroidism Among Patients of a General Medical Department

Abstract

We have measured basal thyrotropin (TSH) in 945 consecutive patients of a general medical department. Additional thyroid tests were carried out in patients with elevated TSH. Thirty patients (3.1%) had subclinical hypothyroidism, i.e. an elevated TSH with no clinical signs and with a normal free thyroxine index. A cause was found in only fifteen of these thirty patients. Thirteen additional patients (1.37%) had mild or overt primary hypothyroidism, three of which were already diagnosed. This prevalence is three times higher than that found in a retrospective survey at the same hospital. Of the ten newly-detected cases five were discharged on thyroid hormone replacement. In two patients the antithyroid drugs which were the cause of hypothyroidism were discontinued. The remaining three patients had severe non-thyroidal illnesses and thyroid hormone was not prescribed. A cause for the hypothyroidism (autoimmune thyroid disease, post-radioiodine, post-thyroidectomy or antithyroid drugs) was established in all but two cases. The data suggest that thyroid function tests (preferably a TSH) should be performed on any patient with prior treatment to the thyroid and, in addition with very broad indications, perhaps even routinely, in all women over 50 years of age.

Clinical Presentation of Spontaneous Primary Hypothyroidism in Adults

“…[11][12][13][14] In this study, the majority of Saudis and non-Saudis were found to be relatively young at the time of diagnosis. Although this observation is not surprising in non-Saudis, the majority of whom, being expatriate employees, are expected to be young, it is intriguing in Saudis.…”

Subclinical hypothyroidism: a historical view and shifting prevalence

“…Across studies, the prevalence of SCH (like overt hypothyroidism) is consistently higher in women than in men (Table 2) (17)(18)(19)(20)(21)23,25,27,(29)(30)(31)(32)(33)(34)(35)(36)(37)(38). In the Whickham study, the prevalence of SCH in women was 7.5%, nearly three times the prevalence in men (2.8%) (19).…”

“…In the early Whickham study in the United Kingdom (N = 2779), 5.0% of individuals older than 18 years were classified as having SCH, defined as TSH > 6 mIU/l in the absence of symptoms of hypothyroidism (19). In 1981, Riniker et al (20) reported a prevalence of SCH of 3.1% among 945 patients in a general medical department in Switzerland. In this study, SCH was defined for asymptomatic individuals as TSH > 6 mIU/l in combination with FT4 > 51 nmol/l (20).…”

“…In 1981, Riniker et al (20) reported a prevalence of SCH of 3.1% among 945 patients in a general medical department in Switzerland. In this study, SCH was defined for asymptomatic individuals as TSH > 6 mIU/l in combination with FT4 > 51 nmol/l (20). Among participants ≥ 18 years of age in a state-wide health fair in Colorado in 1995 (N = 25,862), the prevalence of SCH, defined as TSH > 5.1 mIU/l and thyroxine ≥ 57.9 nmol/l, was 9.0% (21).…”

“…The 20-year follow-up of the Whickham survey demonstrated that the risk of developing overt hypothyroidism in women was approximately 2.6% per year when an elevated TSH (TSH > 6 mIU/l) was present (55). Furthermore, the odds ratio [OR; 95% confidence interval (CI)] of developing overt hypothyroidism was 8 (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) when considering TSH > 6 mIU/l alone and 8 (5-15) when considering a positive test for antithyroid antibodies alone. When elevations in TSH and antithyroid antibodies were both present, the OR (95% CI) of developing overt hypothyroidism was 38 during the 20-year follow-up interval.…”