Free Thyroxine and Free Triidothyronine as an Index for the Assessment of Thyroid Function in Port Harcourt, Rivers State, Nigeria

Abstract

A critical part of diagnosing thyroid disorders is the laboratory evaluation performed through blood testing. A reliable and accurate diagnosis is necessary in order to select the proper treatment options for thyroid disorder patients and help to increase workflow and efficiency. This research was carried out because of increased late diagnosis of thyroid disease in patients suffering from various thyroid disorders. The estimation of free thyroxine, fT₄, and free triodothyronine, fT₃ was done and used as an index for the differential assessment of thyroid function. A total number of nine hundred and seven (907) patients were diagnosed of various thyroid dysfunctions from the subjects that attended the various hospitals/clinics in the city of Port Harcourt, Rivers State, Nigeria, between the months of February, 2010 to April, 2013. The method of enzyme linked immuno sorbent assay (ELISA) was used in carrying out the study. Out of the 907 patients, 532 of them, representing 58.65% were females while 375 of the patients representing 41.35% were males. From the result analysis, 55.46% of the patients diagnosed of primary hyperthroidism had elevated serum levels of both total and free T₃, T₄ with low TSH values, while 3.09% of the hyperthyroid cases had normal total T₄ and T₃ but elevated values of fT₄ and fT₃.  0.88% of the patients with hypothyroidism had normal total T₄ and T₃, but with low serum levels of fT₄ and fT₃ and was diagnosed so clinically. Triiodothyronine (T₃) toxicosis with elevated fT₃ and normal fT₄ serum levels were found in 9.81% of the patients. Non thyroidal illness cases had low serum fT₄ in 9.26% of the patients. Two (about 0.22%) of the patients that were diagnosed of TSH Secreting tumours had an elevated serum fT₄ level in addition to high serum TSH levels. This study showed that fT₃ and fT₄ is actually an index in the differential diagnosis of thyroid diseases.

Keywords: Hyperthyroidism, Hypothyroidism, Toxicosis, Non –Thyroidal, Hormone, Thyroxine, Triidothyronine.