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

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. Therefore the purpose of this chapter is to present concepts to practical diagnosis of thyroid diseases.

Objective: The objective of this study was to establish the usefulness of fT3 and fT4 in the diagnosis of different thyroid diseases. The medical personnel treating thyroid disorders need the appropriate ammunition to approach their patient’s problems. 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.