This work was aimed at determining and comparing the frequency of abnormal levels of thyroid stimulating hormone (TSH) in geriatric outpatients with and without dementia. This cross-sectional study enrolled patients, aged 60 years and older with or Without dementia (established on the basis of DSM-IV-R), from geriatric outpatient unit with third level of medical care. Comparisons were between 33 (34%) patients without dementia versus 26 (58%) with dementia; both among 142 (24%) randomly selected sample (RSS) from unit's register; and the 101 (89%) in the memory-clinic case series (MCCS) of dementia were contrasted with the former. Measurements: TSH, total/free thyroxine, mini-mental-state examination (MMSE), geriatric depression scale (GDS), Hachinski ischemic-score (HIS), and clinical data from the patients' charts. In the above order, high TSH was found in 9 (27.3%, confidence interval (CI) = 12.1-42.5%), 6 (23.1 %, CI = 6.9-46.5%), and 30 (29.7%, CI = 20.8-38.6%), respectively. Low-normal free thyroxine levels accompanied 76% of individuals with elevated TSH; in contrast of Gaussian distribution of free thyroxine in those with TSH in normal ran-c. In conclusion, the high frequency found of hypothyroidism in patients with and without dementia warrants further Studies. Treatment is only being recommended for patients with below range thyroxin levels; while treatment of subclinical hypothyroidism in the presence of cognitive decline will be addressed in the forthcoming studies. (C) 2007 Elsevier Ireland Ltd. All rights reserved.