Tertiary hyperparathyroidism with ectopic mediastinal parathyroid adenoma in a patient with chronic kidney disease and cardiovascular complications: a case report

Abstract Background Hyperparathyroidism includes conditions marked by excessive secretion of parathyroid hormone (PTH), resulting in disruptions in calcium-phosphate metabolism. In individuals with chronic kidney disease (CKD), differentiating secondary hyperparathyroidism from tertiary hyperparathyroidism is frequently challenging due to the overlapping biochemical and clinical characteristics. Ectopic mediastinal parathyroid adenomas are uncommon and complicate localisation and therapy further. Case presentation We present a 66-year-old female with chronic kidney disease, hypertension, and ischaemic heart disease, who had increasing dyspnoea initially attributed to heart failure. Laboratory assessment indicated PTH 238.8 pmol/L, corrected calcium 2.545 mmol/L, phosphorus 1.389 mmol/L, and vitamin D 39.8 nmol/L, suggesting advanced hyperparathyroidism. The primary diagnostic issue was distinguishing tertiary hyperparathyroidism from secondary hyperparathyroidism in the context of chronic kidney disease (CKD). Localisation was accomplished with Tc-99m sestamibi SPECT/CT, revealing a 3 × 2 cm anterior mediastinal lesion consistent with an ectopic parathyroid adenoma. Echocardiography demonstrated significant concentric left ventricular hypertrophy and a large pericardial effusion. Definitive surgical treatment consisting of bilateral neck exploration with thoracoscopic excision of the anterior mediastinal parathyroid gland was recommended following stabilization. However, after counseling, the patient declined surgical intervention and was managed conservatively with ongoing nephrology and endocrinology follow-up. Discussion This case highlights the diagnostic complexity of tertiary hyperparathyroidism in CKD and the crucial role of multimodal imaging in localising ectopic adenomas. Integrating biochemical, radiological, and clinical findings is essential for accurate diagnosis and timely surgical planning. Conclusion This case highlights how modest biochemical irregularities and unusual cardiopulmonary symptoms can obscure ectopic parathyroid disease, emphasising the importance of maintaining a high index of suspicion to guide optimal clinical decision-making. Clinical trial number Not applicable.