Table 1.

Definitions of TSH test classifications

CLASSIFICATION OF TSH TESTS	DEFINITION
Conforming to test-ordering guidelines^*	Test ordered for a patient who presents with ≥ 1 symptoms or signs of primary hypothyroidism or with a previously unresolved investigation with results that might be directly associated with primary hypothyroidism (ie, anemia, hyperlipidemia, prolonged QT interval)
Possibly conforming to test-ordering guidelines^*	Test ordered for a patient who does not present with any symptoms or signs of primary hypothyroidism but who is at increased risk of primary hypothyroidism: female patient aged > 50 y patient with a first-degree relative who has a history of autoimmune thyroid disease patient with a past medical history of an autoimmune disease patient with a history of radiation to the thyroid patient who is taking or who has taken lithium, amiodarone, or an iodine-containing product
Not conforming to test-ordering guidelines^*	Test ordered for the purpose of screening a patient who does not present with any symptoms or signs of primary hypothyroidism and who does not have previously unresolved investigation results that might be directly associated with primary hypothyroidism, and who is not at increased risk of primary hypothyroidism

TSH—thyroid-stimulating hormone.
↵* Based on a predetermined list of 37 symptoms and signs of primary hypothyroidism and on the data abstractors’ clinical judgment of the patient’s presentation and of the clinician’s ordering of the TSH test.