Thyroid Cascade Profile

Aid clinicians in obtaining an appropriate diagnosis for common adult thyroid disorders. The cascade begins with a third-generation thyroid-stimulating hormone (TSH) test. If the TSH result is normal, a euthyroid status is assumed and testing stops. Additional testing is performed only if the initial TSH result is abnormally high or low. The cascade algorithm will select specific tests, based on the results of previously performed tests, which are necessary to arrive at the most appropriate laboratory diagnosis. The assayed value of a test, relative to the reference interval of that specific test, determines which, if any, additional tests are performed. The cascade proceeds, selecting specific tests, until the most probable diagnosis can be made.

Note: Special reflexing. If TSH is <0.450, it will reflex to thyroxine (T₄), free, direct and depending on the thyroxine (T₄), free, direct result, may reflex to a triiodothyronine (T₃), free, both at an additional charge. If the TSH is >4.500, it will reflex to thyroxine (T₄), free, direct and depending on the thyroxine (T₄), free, direct result, may reflex to a thyroid peroxidase (TPO) antibody, both at an additional charge.

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.

This profile is not intended for use in pediatric patients or in monitoring patients receiving treatment for thyroid disease with either ablative or suppressive therapy. It would also not be appropriate to use this procedure to diagnose primary thyroid neoplasm.

Electrochemiluminescence immunoassay (ECLIA)