Thryroid Nodule

Thyroid nodules are very common clinical finding with an estimated prevalence of 3 - 7 %.

Investigation:

Laboratory Evaluation

• Measurement of TSH concentration is the single most useful laboratory test in the initial evaluation of thyroid nodules.

• Thyroid peroxidase antibody should be measured in patient with high TSH level. Patients with raised TPO Ab and a firm, diffusely enlarged thyroid are very suggestive of autoimmune or Hashimoto's thyroiditis.

• Calcitonin level should be measured as it is a useful marker of medullary thyroid carcinoma, especially in patient with family history of MTC or MEN 2.

Diagnostic Imaging Studies

• High resolution USS is the most sensitive test available to detect thyroid lesions. Nodules with malignant potential should be identified and FNA biopsy should be suggested to the patients.

• Thyroid Scintigraphy is useful in hyperthyroid patient to differentiate cold and hot nodule.

Cytological Studies

• Fine needle aspiration cytology/ biopsy has been established as a safe and reliable. FNAC/B results can be

Diagonostic ( satisfactory specimen )

• Benign
• Malignant
• Suspicious

Non-diagnostic ( unsatisfactory speciment )

• Foam cells
• Cyst fluid
• Blood

Interpretation

Hyperthyroidism ( Low TSH ) - need scintigraphy

• Hot nodule - can be MNG or solitary thyroid nodule. MNG need further USS study to exclude for suspicious lesion and if required FNAC/B.

• Cold nodule - need further work up with FNAC/B.

Euthyroid - need further work up depending on the size and risk factors for malignant lesions.

• Risk factors includes:

History of head and neck irradiation
Family history of MTC or MEN 2
Age less than 20 or more than 70
Male sex
Growing nodule
Firm or hard consistency
Fixed nodule
Cervical adenopathy
Persistent hoarseness, dysphonia, dysphagia or dyspnoea

• More than 10 mm or risk factors - need FNAC/B.

• Less than 10 mm and no risk factors - USS first to look for suspicious lesion and if suggestive, FNAC/B.

Hypothroidism ( high TSH ) - need USS scan.

• If suspicious for malignancy on USS - then FNAC/B is warranted.

• If not suscpicious - then TPO Ab is suggested to confirm for Hashimoto's thyroiditis and autoimmune thyroiditis.