The Importance of Laboratory Investigation of Thyroid Hormones in Various Thyroid Dysfunctions in Enugu South Eastern Nigeria

Background: Thyroid disorder remains the disease of major public health importance in Nigeria. Clinical diagnosis in thyroid dysfunction is limited; hence diagnosis and management are dependent on accurate laboratory measurements and interpretation of results.

Objective: The present study was designed to evaluate the importance of serum total triiodothyronine (tT3), total thyroxine (tT4), Free triiodothyronine (fT3) and Free thyroxine (fT4) as reliable indicators to assess thyroid dysfunctions in Enugu Southeastern Nigeria.

Materials and Methods: The study was conducted at Department of Chemical Pathology (Endocrine unit) University of Nigeria Teaching Hospital (UNTH) Enugu, from 2015 - 2017. It comprised of a total of 1182 participants. 336 patients (110 males, 226 females; age range 20-75 years) with hypothyroidism, 336 patients (100 males, 236 females; age range 20-75 years) with hyperthyroidism and 510 healthy subjects (200 males, 310 females; age range 20-75 years) with detailed medical history. After due consent, chest x-ray was done. Blood samples for serum analysis of tT3, tT4, fT4, fT3 and thyrotropin (TSH) were collected between 8 to 10 am using Enzyme Linked Immunosorbent Assay (ELISA) method. The Pearson correlation between tT3, tT4, fT3, fT4 and TSH was determined to identify the valuable indicator for thyroid function besides TSH.

Result: The correlations of tT3 and fT3 with TSH were statistically significant in healthy population P = .003, .015 and r-values were .130 and -.108) respectively. The correlations of fT3 and fT4 with TSH were statistically significant in patients with hypothyroidism and (P <.0001) and r-values were -.480 and -.307 respectively. The correlation of tT3, fT3 and tT4 with TSH were statistically significant in patients with hyperthyroidism and (P<0001) and r-values were -.459, - .337 and -.313 respectively.

Conclusion: TSH, tT3 and fT3 are the indicators of thyroid function in healthy population, TSH fT3,fT4 in hypothyroidism. TSH, tT3 and tT4 in hyperthyroidism.