*Procalcitonin is usually produced in* [A] Thyroid [B] Liver [C] Bone Marrow [D] Plasma cells ANSWER [A] Thyroid • Procalcitonin is produced by parafollicular cells (C cells) of the thyroid and by the neuroendocrine cells of the lung and the intestine. • Procalcitonin is usually produced in the thyroid, during bacterial infections it is released by the neuroendocrine cells of the lung and intestine and as an acute-phase reactant. Thyroid C cells - pre-procalcitonin – procalcitonin - calcitonin