MEA IIb does not have the parathyroid component and also has a Marfanoid habitus and mucosal neuromas. All patients with medullary carcinoma should get a urinary metanephrine screen. If this is positive, the pheochromocytoma should be found and excised first. All first degree relatives of patients with medullary carcinoma should have a calcitonin level. If this is normal, they should have a pentagastrin infusion study to see if they secrete too much calcitonin.
Total thyroidectomy is indicated if they have abnormal studies.
Interestingly, the calcitonin does not always go down after total thyroidectomy. If it does, the patient can be followed with pentagastrin infusion studies. It may also characteristically produce amyloid, which stains green with congo red. Most authors recommend sub-total or total thyroidectomy. In patients with neck mass, a neck dissection is indicated.