Renal hyperparathyroidism (rHPT) as a consequence of an abnormal calcium balance is a frequent complication in patients with chronic kidney disease (CKD). However, calcium homeostasis is also regulated by calcitonin. The relevance of elevated calcitonin levels in patients with rHPT is unclear. This report presents a case of a patient with CKD and mild rHPT scheduled for thyroidectomy for a suspected medullary thyroid carcinoma (MTC) within a mononodular goiter. A hemithyroidectomy with resection of both adjacent parathyroid glands and unilateral central lymph node dissection was performed. Histopathology revealed no evidence of MTC. The rHPT, calcitonin and pentagastrin test subsequently normalized and follow-up revealed no evidence for MTC within the remaining right thyroid lobe. Elevated calcitonin levels in patients with CKD may reflect a physiological response to rHPT than rather represent MTC. The thresholds for calcitonin levels need to be better defined in affected patients to determine the optimal extent of surgical resection.