Parathyromatosis Recurrent Hyperparathyroidism and Refractory Hypercalcemia Successfully Managed With Addition of Denosumab: A Case Report

Introduction: Parathyromatosis is a rare cause of recurrent hyperparathyroidism in which multiple nodules of hyperplastic parathyroid tissue are scattered throughout the neck and superior mediastinum. It is proposed to be a result of spillage and seeding of parathyroid tissue during parathyroid surgery. It presents as recurrent or persistent PTH mediated hypercalcemia. Management of Parathyromatosis is challenging and frequently refractory to surgical intervention; hence there is a need for an effective medical treatment. Case: 34 year old female was diagnosed with hyperparathyroidism in 2003 at the age of 16 years. She presented with fatigue, muscle weakness, bone pain and markedly elevated calcium and PTH levels. Sestamibi scan showed parathyroid adenoma with a cystic lesion. She underwent surgical removal, which was complicated by parathyroid cyst rupture. However, the patient remained asymptomatic for 4 years of follow-up. Then in 2007, she had a recurrence of the same initial presentation with laboratory values confirming relapse of hyperparathyroidism. A nuclear parathyroid scan showed remnant parathyroid tissue inferior and posterior to the right thyroid lobe along with multiple subcutaneous nodules. Neck exploration was performed, and histopathological examination showed multiple nodules of hyperplastic parathyroid tissue and cystic changes consistent with the diagnosis of Parathyromatosis. Attempts at satisfactory surgical resection failed, and the patient had recurrent replaces with multiple hospitalizations for nephrolithiasis and had undergone 4 more surgical interventions for remnant parathyroid tissue in a span of 10 years (2008–2018). We started the patient on cinacalcet in August 2018 with an initial dose of 60 mg/day that was gradually increased to 180 mg/day, besides vitamin D analog. This helped in achieving a partial but not full control of calcium levels, so we decided to add Denosumab in April 2019 at the dose of 60 mg SC every 6 months. Dexa scan was done before starting treatment and showed a normal Z score. This regimen has successfully maintained a stable calcium level with normal corrected calcium, and our patient has been in remission with no recurrence of renal stones or other symptoms for the past 18 months, with the last follow-up showing a calcium level of 2.64 mmol/l (2.2–2.65), PTH of 23 pmol/l (1.1–8.43), vitamin D of 24 ng/ml (20–32), albumin of 38 g/L (35–52) and creatinine of 58 umol/l (49 - 90), compared to calcium level of 2.93 mmol/l, PTH of 50 pmol/l and Vitamin D 13 ng/ml before starting treatment. Conclusion: Although it is a rare condition, Parathyromatosis should be kept as a differential diagnosis in the event of recurrent hyperparathyroidism. The Addition of Denosumab to Cinacalcet can make a big difference in achieving a successful medical treatment of the condition, therefore avoiding the detrimental effects of long-standing hypercalcemia.

O62: INTRA-OPERATIVE ADJUNCTS IN MINIMALLY INVASIVE RADIO-GUIDED PARATHYROIDECTOMY AT A SPECIALIST ENDOCRINE SURGERY CENTRE

Introduction Primary Hyperparathyroidism (PH) is common cause of hypercalcaemia (0.3% of the population). Minimally invasive radio-guided parathyroidectomy (MIRP) has been made possible due to advancements in pre-operative imaging i.e. sestamibi scans allowing localisation of areas of parathyroid hyperactivity. Method Due to the disagreement in the literature regarding which intra operative adjunct is best used in MIRP surgery to decrease recurrence, the rationale for this study is to examine and compare the performance of these adjuncts in consecutive patients i.e. 1. Intra operative PTH assay (IOPTHA) 2. Tc-99m radio-guidance using a gamma probe and the 20% rule 3. Frozen section analysis. Result 45 MIRP procedures were carried out between 01/07/2018 and 30/10/2019. 77.8% were females; mean age was 62 years (range 30 - 79). Final pathology showed that in 43 of the cases parathyroid tissue was correctly removed; thyroid tissue was identified for the other 2 cases. 20% rule was positive in 43 out of the 45 cases and negative in 2 (sensitivity 100%, specificity 100%). A drop in IOPTHA greater than 50% was found in 41 out of the 45 cases but not in 4 (sensitivity 93.9%, specificity 100%). Frozen section was 100% concordant with final pathology (45/45). AUC analysis showed no significant difference in the performance of these tests (p = 0.15) but was around 1 for 20% rule and Frozen section. Conclusion When radio-guidance and frozen sections are added to IOPTHA, the success rate of parathyroidectomy is markedly improved. Using them together will greatly reduce recurrent hyperparathyroidism. Take-home message When radio-guidance and frozen sections are added to Intra-operative PTH assays in Minimally Invasive Radio-Guided Parathyroidectomy, the success rate of parathyroidectomy is markedly improved. Using them together as in our study will greatly reduce the incidence of recurrent hyperparathyroidism and thus recurrent surgery.

Surgical Outcomes of Subtotal Parathyroidectomy for Renal Hyperparathyroidism

Objectives. The aim of this study was to evaluate the effectiveness of subtotal parathyroidectomy for patients with renal hyperparathyroidism.Methods. We studied 25 patients with renal hyperparathyroidism who underwent subtotal parathyroidectomy from October 2002 to October 2017. We analyzed serum intact parathyroid hormone (iPTH), calcium, and inorganic phosphorus levels before and at multiple time points following surgery, and evaluated the surgical outcomes and complications.Results. Of the 25 patients, 13 (52%) were male and 12 (48%) were female, and the mean age was 53.4±9.3 years. The mean duration of dialysis before parathyroidectomy was 156.8±79.5 months. Mean preoperative serum iPTH and calcium levels were 1,199.0±571.3 pg/mL and 10.5±1.0 mg/dL, respectively. At 6 months postoperatively, the mean iPTH and calcium levels decreased to 49.2±47.6 pg/mL (<i>P</i><0.01) and 8.0±1.0 mg/dL (<i>P</i><0.01), respectively. Recurrent hyperparathyroidism occurred in two patients: one subsequently underwent kidney transplantation and the other continued hemodialysis and maintained normal calcium levels. One patient developed postoperative permanent hypoparathyroidism.Conclusion. Subtotal parathyroidectomy is a safe and effective surgical treatment for renal hyperparathyroidism.

SAT-386 Inconsistent Bilateral Arm Serum PTH Testing in Recurrent Hyperparathyroidism in a Patient Status-Post Parathyroid Auto-Transplantation

Background: More than 95% of patients with primary hyperparathyroidism will be cured with the initial operation by an experienced surgeon. However, localization of hyperparathyroid recurrences, especially after extensive surgery becomes challenging. For patients with transplanted parathyroid glands into the forearm, there may be utility in bilateral arm serum PTH testing to help with localization. Clinical Case: A 65-year-old woman presented to the clinic with primary hyperparathyroidism in 2008. After a localization study, she had a partial parathyroidectomy but continued to have persistent biochemical hyperparathyroidism despite negative localization studies. She was then referred to another institution for further studies. Follow up Sestamibi scans were negative but 4D-CT scans assisted in localizing the presence of a superior parathyroid gland adenoma which was later removed in 2011. During this time, the left inferior parathyroid gland was auto-transplanted into the left forearm. Again, her calcium and PTH levels rose despite negative Sestamibi scans showing no abnormalities in post-operative beds or in the forearm. Review of previous labs revealed elevated PTH levels in the ranges of 80-110 pg/mL since 2012-2019. The patient’s most recent PTH was 2408 pg/mL. At that point, the decision was made to repeat the labs on the left and right forearms simultaneously and labs showed PTH levels of 1283 pg/mL and 118 pg/mL, respectively. Repeat Sestamibi scan following these labs demonstrated evidence of increased radiotracer uptake in the region of the prior transplanted parathyroid tissue with no neck uptake concerning for hyperparathyroidism due to auto-transplanted hyperplastic tissue. Conclusion: This case demonstrates the utility of bilateral arm serum PTH testing in the evaluation of recurrent hyperparathyroidism in patient’s status-post parathyroid auto-transplantation.