Effect of Age, Sex and Goiter on Thyroid Function Tests in Euthyroid Individuals Establishment of Norms for Lahore and Surrounding Areas

The aim of this study was to investigate the effect of age, sex and goiter on thyroid hormone levels in the serum of euthyroid individuals and to define normal levels of thyroid related hormones of the population of Lahore and its surrounding areas. Subjects were recruited from the patients referred to Center for Nuclear Medicine (CENUM) Lahore for thyroid function tests The study was conducted on 500 individuals, who were euthyroid according to the laboratory results as well as clinical assessment and free from any disease or medication known to alter thyroid function test. Thyroid function tests included the measurement of serum total triiodothyronine (T3), total thyroxine (T4) and thyroid stimulating hormones (TSH). Appropriate t-test was applied for statistically significant difference for each variable against age. sex and goiter and where significant difference existed, regression analyses were made. It was found that the difference in thyroid hormone levels was non-significant regarding sex. presence or absence of goiter and goiter shape. There was no age related change in serum TSHlevels, whereas serum Tj levels showed significant (p 0.0025) decline with age in both the sexes.Serum T4 levels decreased significantly (p 0.025) with age in males and females; however in males its levels were stable after the age of 60 years. The results of this study revealed that normal concentration ranges (95 %) of T4, T3 and TSH in serum of untreated normal Pakistani individuals were 64-146 nmol/l, 0.9-2.9 nmol/l and 0.26-4.03 mlU/l respectively.