BACKGROUND: Thyroid function test is an essential tool in the
diagnosis of
thyroid dysfunction. To date, it is still controversial which diagnostic
algorithm is best applicable to clinically
hyperthyroidism patients .
OBJECTIVE: To compare various
algorithms of
thyroid function tests in the
diagnosis of
hyperthyroidism .
METHOD: Patients from the endocrine clinic, King Chulalongkorn Memorial
Hospital were investigated for
thyroid function tests (T3, T4, FT3, FT4 and TSH).
Hyperthyroidism was defined as an elevated either FT3 or FT4 with suppressed TSH. The authors compared the
effectiveness in
hyperthyroidism diagnosis among
algorithms by using
sensitivity ,
specificity ,
positive predictive value and
negative predictive value .
RESULTS: Of all 452
patients in the present study, 94.24 percent were
women . There were 206
hyperthyroidism , 30 subclinical
hyperthyroidism , 1 subclinical
hypothyroidism , 8
primary hypothyroidism and 207 normal subjects. The
incidence of T3 toxicosis was 16.02% while that of T4 toxicosis was 2.16%. After the
effectiveness analysis of these
algorithms , FT3 and TSH is the most optimal test with 97.57%
sensitivity and 100%
specificity . Compared to FT4 and TSH, it gave 83.98%
sensitivity and 100%
specificity .
CONCLUSION: According to the high
incidence of T3 toxicosis in the present study, FT3 and TSH should be the initial test for
diagnosis of
hyperthyroid patients in an
outpatient setting and FT4 should be measured subsequently in case of suspected T4 toxicosis.