<prompt> Screening method for medullary carcinoma thyroid is :Serum calcitoninS. calciumS. alkaline phosphateS. acid phosphatase  <response>: Answer is A Serum Calcitonin: Medullary Carcinoma Thyroid are tumors of para-follicular C cells derived from the neural crest, are not derived from the cells of thyroid follicles. Since these pars follicular C cells secrete CalcitoninQ, high level of serum Calcitonin 0.08 zsgm1 are found. These levels fall after resection, will rise again if the tumor recurs, making it the ideal candidate for screening tests. Also note :These cancers are associated with HypocalcemiaQ because calcitonin counteracts parathormnone. 