Журнал заболеваний щитовидной железы и терапии
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Use of Paired Test in Management of Thyroid Disorders

Tofail Ahmed, Hajera Mahtab, Tania Tofail, AHG Morshed, Shahidul A Khan

Aim and methods: This study is to explore utility of paired FT4 and TSH test as a tool to classify functional status of Thyroid. We classified 58166 paired test results into the all 9 possible classes and determined frequency of class; reference ranges of FT4 and TSH for class, their mean differences (MD) between classes and pattern of association in class and in their cohorts.

Results: FT4 and TSH of Euthyroid class (43242) are (14.65 to 14.70 pmol/ml) and (2.44 to 2.46 µIU/ml as 95% Confidence Interval respectively and there is no association between them (r-.049; sig.000). Major bulk of abnormal thyroid function (98.26%) is constituted by 4 classes of primary category–namely Primary Hypothyroid, Primary Hyperthyroid, Compensated Hypothyroid and Compensated Hyperthyroid. These 5 classes have significant correlation between their FT4 and TSH (sig. of r .000) and their hormones levels are different among all classes (sig. of MDs .000). The rest 4 classes of secondary category – namely Secondary Hypothyroid, Secondary Hyperthyroid, Isolated Hypothyroximia and Isolated Hyperthyroximia are rare, correlations between their hormones are not significant in any class (sig. of r ≥.063) and all hormones are not different among all classes of this category. Cohort analysis supported the findings on correlations. So, during classification the tool exploits Thyro-pituitary axis status and its euthyroid and all 4 classes of primary category have homogenous thyro-pituiary feedback control.

Conclusion: Paired Test defines 9 classes with class specific correlation pattern between FT4 and TSH and their ranges. We opine to use this tool; because in diagnostic setting it will reduce the burden of etiological investigations to a few for a class and in follow-up setting use of the reference range of FT4 of the Euthyroid class as the biochemical target of treatment will ensure a cost effective strategy in Thyroid medicine.