From the Guidelines
For thyroid nodules, the recommended initial blood work includes thyroid-stimulating hormone (TSH) as the primary test, which should be ordered first to detect thyroid dysfunction, as supported by the most recent study 1. If TSH is abnormal, then free thyroxine (Free T4) and sometimes free triiodothyronine (Free T3) should be added to further characterize the thyroid function. Thyroid antibodies such as thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) may be useful if autoimmune thyroid disease is suspected. Calcitonin testing can be considered in patients with a family history of medullary thyroid cancer or multiple endocrine neoplasia, as recommended by 1 and 1. Thyroglobulin levels are not typically useful in the initial evaluation of thyroid nodules but may be used for monitoring after thyroid cancer treatment. These tests help determine if the nodule is functioning abnormally and provide information about the underlying thyroid status, which guides further management decisions, including whether fine needle aspiration biopsy is needed, as outlined in 1 and 1. Most thyroid nodules are benign, but blood work helps identify those that require additional evaluation.
Key Points:
- TSH is the initial test for detecting thyroid dysfunction
- Free T4 and Free T3 may be added if TSH is abnormal
- Thyroid antibodies may be useful if autoimmune thyroid disease is suspected
- Calcitonin testing may be considered in patients with a family history of medullary thyroid cancer or multiple endocrine neoplasia
- Thyroglobulin levels are not typically useful in the initial evaluation but may be used for monitoring after thyroid cancer treatment
Recommendations:
- Order TSH as the initial test for thyroid nodules
- Consider additional tests based on TSH results and clinical suspicion
- Use the results to guide further management decisions, including fine needle aspiration biopsy if necessary, as recommended by the most recent and highest quality study 1.
From the Research
Thyroid Blood Work for Thyroid Nodules
To assess thyroid nodules, the following thyroid blood work is recommended:
- Serum thyroid-stimulating hormone (TSH) measurement 2, 3, 4
- Measurement of peripheral thyroid hormones, if necessary 3
- Thyroid radionuclide scan, if serum TSH levels are low 2, 4
Indications for Additional Testing
Additional testing, such as fine-needle aspiration biopsy, may be indicated based on:
- Ultrasound characteristics of the nodule 2, 5, 4
- Size of the nodule 5, 4
- Clinical and sonographic risk factors for thyroid cancer 2, 5
- Suspicious sonographic patterns, including solid composition, hypoechogenicity, irregular margins, and microcalcifications 5
Molecular Testing
Molecular testing may be used to guide treatment when fine-needle aspiration biopsy yields an indeterminate result 4, 6
- Molecular testing detects mutations associated with thyroid cancer and can help inform decisions about surgical excision vs. continued ultrasound monitoring 4
Special Considerations
- Pregnant women with nonfunctioning thyroid nodules and children with thyroid nodules should be treated similarly to nonpregnant adults, with the exception of molecular testing, which has not been validated in these populations 4
- Routine thyroid cancer screening is not recommended, except in high-risk individuals, as the detection of early thyroid cancer has not been shown to improve survival 2