[Diagnosis and treatment of persistent or recurrent hyperthyroidism]

Reasons for postoperative persistence of primary hyperparathyroidism (pHPT) are missed parathyroid adenoma, incomplete removal of multiple altered pararthyroid glands, and rare variants of localisation. A reoperation is indicated in symptomatic patients if calcium serum levels are elevated above 2.9 mmol/l. Preoperatively, cervical sonography and 99mTc sestamibi scintigraphy should be carried out. Additionally, selective venous blood sampling and nuclear magnetic resonance tomography can be of use. After successful localization, a unilateral approach is advisable. If position remains unclear, bilateral exploration is required. In secondary hyperparathyroidism (sHPT), renal function is crucial for development of recurrence. For postoperative persistence, identification of less than four pararthyroid glands or leaving of the thymus are the main reasons. Before reoperation it has to be clarified if parathyroid hyperfunction is caused by persisting cervical or mediastinal tissue, or if hyperfunction of autotransplanted tissue in the forearm is evident. Diagnostic and operative procedures are similar to those used in pHPT.