TSI (Thyroid Stimulating Immunoglobulin)

CPT: 86800
Thyroid

What This Test Measures

Detects antibodies that stimulate TSH receptors; diagnostic for Graves' disease (hyperthyroidism).

Preparation

No fasting required
If taking T3 medication (liothyronine/Cytomel), draw at least 12–24 hours after your last dose for an accurate TSH. If splitting T3 doses, draw at your natural trough. Biotin supplements — even in multivitamins — can falsely skew thyroid results: discontinue at least 2 days before testing. No fasting required unless combined with other tests.

General guidelines only. Requirements vary by lab and individual. Confirm with your provider before adjusting any medications.

Turnaround Time

Varies by lab

Clinical Notes

Confirmatory test for Graves' disease; also called TRAb or TSHR Ab

ICD-10 Codes

Common diagnosis codes associated with this test. Codes are assigned by your provider.

E03.9Hypothyroidism, unspecified
E05.90Hyperthyroidism, unspecified
E06.3Autoimmune thyroiditis
R53.83Other fatigue
Z79.899Other long term drug therapy

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Lab Codes

Proprietary codes used by each lab for this test.

LabCorp
086698(order)
Quest Diagnostics
30551(order)

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Related Tests

Free T4 (Thyroxine, Free)

CPT: 84439

Free T3 (Triiodothyronine, Free)

CPT: 84481

Free T4 Index (T7)

CPT: 84479, 84436

Anti-TPO (Thyroid Peroxidase Antibody)

CPT: 86376

Anti-Thyroglobulin Antibody (TgAb)

CPT: 86800

Comprehensive Thyroid Panel

CPT: 84443, 84439, 84481, 84482, 86376, 86800

For informational purposes only

This page is for educational and research purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. ICD-10 and CPT codes are assigned by your healthcare provider. Always consult a qualified healthcare provider before ordering any lab test or making decisions about your health.