MLT GlobeThyroglobulin (Tg)
Thyroid · also called Tg, Serum thyroglobulin
What it measures
Thyroglobulin is the protein in which thyroid hormones are stored and is made only by thyroid tissue. After total thyroidectomy for differentiated thyroid cancer, it serves as a tumour marker for residual or recurrent disease.
Specimen and preparation
- Specimen: Serum or lithium-heparin plasma
- Tube: Gold top
- Preparation: Always test with anti-Tg antibodies; use the same laboratory and method for serial monitoring.
Reference range
| Group | Range |
|---|---|
| Intact thyroid | 3–40 ng/mL |
| After thyroidectomy + ablation | <0.2 (undetectable) ng/mL |
Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.
Causes of high values
- Recurrent or metastatic thyroid cancer
- Goitre and thyroid nodules
- Graves disease and thyroiditis
- Recent fine-needle aspiration or surgery
Causes of low values
- Factitious thyrotoxicosis (exogenous hormone)
- Anti-Tg antibody interference
- After total thyroidectomy
Method
Immunometric chemiluminescent assay; LC-MS/MS when antibodies are present
Good to know
Not used to diagnose thyroid cancer in someone with an intact thyroid.
Related tests
📱 Practise with a timer, track your score and earn certificates in the free MLT Globe app – Google Play or practise online.