Vince
Super Moderator
Henry H. Lindner1 Current professional guidelines for the diagnosis and treatment of hypothyroidism abandon clinical medicine for a laboratory exercise: TSH and free T4 normalization. This approach is both illogical and ineffective. The TSH level is not a measure of thyroid hormone sufficiency in any given patient, either untreated or treated; reliance on the TSH produces both under- and over-diagnosis and undertreatment. Dysfunctional central hypothyroidism with a normal TSH may be more common than primary hypothyroidism, and TSHnormalizing T4 therapy neither normalizes T3 levels nor restores euthyroidism. The TSH test is useful only for investigating the cause of clinically-diagnosed hypothyroidism. The free T4 and free T3 levels are more direct indicators of thyroid suffficiency, but their reference ranges have inappropriately low lower limits due to laboratories’ inclusion of unscreened persons and hypothyroid patients in their samples. A normal free T4 does not imply thyroid sufficiency. The diagnosis and treatment of hypothyroidism must clinical, guided by signs and symptoms first and by the free T4 and free T3 levels second. Every symptomatic patient with relatively low free T4 and/or free T3 levels deserves a trial of T4/T3 combination therapy titrated to obtain the best clinical response. The ultimate test of whether a patient is experiencing the effects of too much or too little thyroid hormone is not the measurement of hormone concentration in the blood but the effect of thyroid hormones on the peripheral tissues.1
