Thyroid nodule laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Laboratory findings in a patient with a thyroid nodule may reveal abnormalities in serum thyrotrophin, serum antithyroperoxidase, free T4, T3, serum thyroglobulin and plasma metanephrines. These findings may vary depending upon whether the nodule is hot or cold.

Laboratory Findings

Test	Indication	Finding
Serum thyrotropin	In all thyroid nodules	Increased in hot nodules that secrete TSH Normal/Decreased in most of the cold/malignant nodules
Serum antithyroperoxidase level	If suspected to Hashimoto’s thyroiditis	Increased
Free T4	If suspected to hot, thyroid hormone producing nodule	Increased
T3	If suspected to thyrotoxicosis	Increased
Thyroglobulin	Routine measurement is not recommended by ATA	Increased May be elevated in most thyroid diseases and are an insensitive and nonspecific test for thyroid cancer
Basal serum calcitonin	In patients with positive family history of medullary thyroid carcinoma In any patients with family history of MEN In any patients with concomitant hormonal abnormalities	Increased Greater than 100 pg=mL, medullary cancer is likely present 39 Routine measurement: Not recommended due to unresolved issues of sensitivity, specificity, and costeffectiveness
Plasma metanephrine testing	In patients suspected to MEN to evaluate pheochromocytoma	Increased
24-hour urinary collection for catecholamines and metanephrines	In patients suspected to MEN to evaluate pheochromocytoma	Increased

Molecular markers

Thyroid specific molecular markers may be helpful in patients with intermediate cytology on FNA to decide on disease management:

BRAF
RAS
RET
- Mostly seen in papillary thyroid cancer (PTC)
Pax8-PPARg
Galectin-3

References

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