Endocrine Abstracts

Background: Renal hyperparathyroidism (rHPT) may affect up to 30% of dialysispatients with end-stage renal disease (ESRD). rHPT is associated with an increased risk of cardiovascular events (CE) and bone diseases such as pain or renal osteodystrophy. Total or subtotal parathyroidectomy may be a chance to reduce the severity of the symptoms and decrease the risk of CE and death. Pre-operative scintigraphy and ultrasound diagnostics in rHPT may be insufficient at even up to 60% of the patients. PET/CT examinationusing the new tracers may be helpfulto localize parathyroid glands in such cases.

Clinical Case: We present the case of a 46-year-old woman with ESRD who underwent a kidney transplant in 2002, in whom ESRD relapsed in the mechanism of chronic antibody mediated graft rejection. Patient was on dialysis since 2014. Time of dialysis was 12 hours per week and the dialysis was adequate. Due to persistent high level of PTH, the occurrence of pathological fracture of the tibia, and presence of the brown tumors of the pelvic bones, the patient received cinacalcet (90 mg/d). During cinacalcet treatment minimal concentration of PTH was 1223 pg/ml and patient reported bone and joints pain, fatigue and pruritus. US of the neck and parathyroid scintigraphy with ^99mTc-MIBI revealed no pathological features. In February 2019 PET/CT with ¹¹C-methionine (¹¹C-MET) was performed, showing high tracer accumulation in the left lower parathyroid gland and in the numerous brown tumors of the ribs. In June 2019 patient underwent subtotal parathyroidectomy and parathyroid adenoma in histopathology examination was reported. On the first day after the surgery PTH serum level drop to 236 pg/ml, but then started to rise again till 823 pg/ml and hypocalcemia occurred. Hungry bone syndrome (HBS) was suspected. Patient received calcium oral supplementation and 6-week post-operative follow-up ¹¹C-MET PET/CT examination revealed no foci of pathological marker accumulation in the parathyroid glands what allowed to exclude rHPT recurrence, giving confirmation of the HBS. Significant reduction in the size and number of brown tumors in the bones was observed additionally. Eight weeks after surgery, the PTH concentration was 281 pg/ml with normocalcemia and slightly elevated phosphate concentration, and the patient reported a significant improvement in well-being.

Conclusion: 1. ¹¹C-MET PET/CT examination was a useful tool for setting best surgical treatment and postoperative follow up of a patient with rHPT

2. The HBS after successful surgical treatment of rHPT can be a potent parathyroid stimulating factor and mimic rHPT recurrence.