Clinical Endocrinology (2009) 70, 961–967 doi: 10.1111/j.1365-2265.2008.03421.x © 2009 The Authors Journal compilation © 2009 Blackwell Publishing Ltd 961 ORIGINAL ARTICLE Blackwell Publishing Ltd Alterations in thyroid function tests in aged hospitalized patients: prevalence, aetiology and clinical outcome P. Iglesias*, A. Muñoz†, F. Prado†, M. T. Guerrero†, M. C. Macías†, E. Ridruejo†, P. Tajada‡ and J. J. Díez§ Departments of *Endocrinology, †Geriatrics, and ‡Biochemistry, Hospital General, Segovia, Spain, §Department of Endocrinology, Hospital Ramón y Cajal, Madrid, Spain Summary Background Thyroid dysfunction is common in aged people and has recently been associated to mortality. Aims Our aims have been (1) to assess the prevalence of alterations in thyroid function tests in hospitalized patients over age 60 years and (2) to study the relationship between thyroid functional status and mortality during hospitalization. Methods We studied a group of 447 patients (62% women), aged 61–101 year, hospitalized during 2005. Thyroid dysfunction was assessed by measuring serum concentrations of thyrotrophin (TSH), free thyroxine (FT4), and free thriiodothyronine (FT3). Thyroid autoimmune status was evaluated through thyroid peroxidase (TPO) and thyroglobulin (TG) antibodies quantification. Results Twenty-one patients (4·7%, 19 women) showed previously known thyroid dysfunction. 332 patients (74·3%) showed alterations in thyroid function tests. Euthyroid sick syndrome (ESS) was the derangement more frequently found (n = 278, 62·2%). After excluding ESS patients, 60 patients (13·4%) showed thyroid dysfunction: overt hypothyroidism, 14 (3·1%); subclinical hypothyroidism, 25 (5·6%); overt hyperthyroidism, 11 (2·5%), and subclinical hyperthyroidism, 10 patients (2·2%). Thyroid autoimmunity was positive in only 4·0% and 2·3% of patients, for TPOAb and TgAb, respectively. The presence of alterations in thyroid function tests was positively associated with the age of the patients and mortality during hospital stay (P < 0·001). Serum levels of FT3 were negatively related to death during hospitalization (OR 0·56; CI 95%, 0·38–0·81; P < 0·01). Conclusions About three quarters of patients admitted in our geriatric unit exhibited alterations in thyroid function tests. This finding was associated with elevated age and poor prognosis. The reduction of FT3 values was a powerful predictor for mortality during hospitalization in elderly patients. (Received 4 June 2008; returned for revision 15 July 2008; finally revised 2 September 2008; accepted 2 September 2008) Introduction Thyroid dysfunction affects a significant portion of the general population. 1,2 Epidemiological studies performed in the last years have shown that the prevalence of hypothyroidism ranges between 1 and 7%. 1–5 Most studies have also found a higher prevalence of hypothyroidism in women, increasing with age. Prevalence of hyper- thyroidism has been found to range 0·5–3·0%. 2,5 This prevalence is higher than 5% when considering the subclinical hyperthyroidism. 5 Also in this case the prevalence is more elevated in women and increases in elderly population. 6,7 Thyroid disorders in the elderly are associated with significant morbidity if they are not treated. 8 Several studies have related thyroid status with morbidity and mortality in old age. 9–12 An abnormally low levels of thyrotrophin (TSH) or elevated levels of free thyro- xine (FT4) were associated with increased mortality rate; and, on the contrary, a higher TSH level was associated with a lower mortality. 11,12 We performed a cross-sectional study in a large cohort of elderly patients admitted to our hospital for an acute disease. Our aim has been to assess the prevalence (previously known and unknown) and the aetiology of thyroid dysfunction, and the prevalence of the euthyroid sick syndrome (ESS) in this population, as well as to study the relationship between these alterations and mortality during hospitalization in these patients. Patients and methods Patients A cross-sectional study including all patients older than 60 years that were hospitalized during 2005 was carried out. All admitted patients in our geriatric unit were included in the study regardless of the cause of hospitalization. A detailed clinical history, review of the previous case record, and complete physical examination were performed in every patient. Functional status at entry was evaluated by using the modified version of Barthel index. 13 This index evaluates 10 basic activities of everyday life with a score that ranges from 0 (maximal dependence) to 100 (maximal independence). All deaths during hospitalization were registered. This study was approved by our local ethical committee and informed consent was given by subjects prior to participation in the study. Correspondence: Dr Pedro Iglesias, Department of Endocrinology, Hospital General, Ctra. de Avila s/n, 40002 Segovia, Spain, Tel.: +34 921 41 9450; Fax: +34 921 44 0532; E-mail: piglesias@hgse.sacyl.es