Normal Reference Range for Serum TSH, Free T4, Total T4, and Total T3 on Roche® Platforms in Basrah, Iraq

Background: Thyroid function tests are mandatory in clinical practice because symptoms and signs are not reliable to discriminate between various types of thyroid disease. Aim: The aim of this study was to determine assay-specific reference range for serum free T4, total T4, total T3 and TSH among healthy non-pregnant adult cohort for Roche® platforms in Basrah (Southern Iraq) from single laboratory in a tertiary center using indirect approach of the available data. Methods: A Cross sectional study for non-pregnant adults 19 years and above. Sera were analyzed by using cobs e411 for thyroid functions tests. Results: Total enrolled persons were 10,078. The 95% reference intervals for TSH were 0.20-6.50 μIU/mL, which increased with age though not linear, for free T4 were 0.8-1.70 ng/dL, for total T4 were 3.78-15.33 μg/dL, and for total T3 were 0.80-2.50 ng/mL. Colcusion: Cobs e411(Roche® analytical platform) analyzer reference range for thyroid function  cannot be applied for Iraqi population .