Second-order testing for autoimmune thyroid disease, including:
Differential diagnosis of etiology of thyrotoxicosis in patients with ambiguous clinical signs or contraindicated (eg, pregnant or breast-feeding) or indeterminate thyroid radioisotope scans
Diagnosis of clinically suspected Graves disease (eg, extrathyroidal manifestations of Graves disease: endocrine exophthalmos, pretibial myxedema, thyroid acropachy) but normal thyroid function tests
Determining the risk of neonatal thyrotoxicosis in a fetus of a pregnant female with active or past Graves disease
Differential diagnosis of gestational thyrotoxicosis versus first-trimester manifestation or recurrence of Graves disease
Assessing the risk of Graves disease relapse after antithyroid drug treatment
A combination of TSI (Thyroid-Stimulating Immunoglobulin, Serum) and THYRO (Thyrotropin Receptor Antibody, Serum) is useful as an adjunct in the diagnosis of unusual cases of hypothyroidism (eg, Hashitoxicosis)
Specimen Type
Serum
Specimen Requirements
Preferred: Red Top
Acceptable: Serum Gel
Minimum Sample Volume
0.1 mL
Stability
Frozen (preferred): 60 days
Refrigerated: 7 days
Ambient: 24 hours
Unacceptable Specimen Conditions
Gross hemolysis
Limitations
Positive results are strongly indicative of Graves disease, but do not always correlate with the presence and severity of hyperthyroidism
Patients with Hashimoto disease may have an elevated thyroid-stimulating immunoglobulins (TSI) index, which can be above 1.8. A TSI index of above 1.3 and less than or equal to 1.8 also is occasionally observed in various other thyroid disorders, including nodular goiter, and subacute thyroiditis
