<prompt> Initial preferred investigation for thyroid nodule is:FNACRadionucleide testThyroid function testUSG  <response>: Initial investigation done in STN is thyroid function testTFT Investigation of choice in STN for diagnosis is FNAC Solitary Thyroid Nodule: Initial investigation done in STN is thyroid function test TFT If TFT is raised, next investigation is thyroid scan , For hot nodules, RAI ablation or surgery is done; For warm or cold nodules follow-up or surgery If TFT is normal, USG is done Aspiration in cystic lesion, FNAC for solid or heterogenous lesions Investigationn of choice in STN for diagnosis is FNAC. Ref: Sabiston 20th edition Pgno: 890 