Eucalcemic PTH Elevation After Parathyroidectomy for Primary Hyperparathyroidism (PHPT)

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 199-237-Disorders of Parathyroid Hormone & Calcium Homeostasis
Translational
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-222
Audrey Elisabeth Arzamendi*, Miya Elizabeth Allen and Alison Marie Semrad
UC Davis Medical Center, Sacramento, CA
Background:  Approximately 40% of patients undergoing parathyroidectomy for PHPT will demonstrate eucalcemic PTH elevation (ePTH) 6 months after surgery. While this is associated with a 4.5-fold increased risk of PHPT recurrence, the majority of patients with ePTH will remain disease-free. Certain risk factors may predict such non-pathologic ePTH.

Clinical Case:  A 65-year-old male presented to the ED for nephrolithiasis, and was found on CT to have multiple spinal lytic lesions. Labs showed hypercalcemia (13.1 mg/dL, n8.6-10.5 mg/dL) and elevated PTH (1444 pg/mL, n12-88 pg/mL), consistent with PHPT. 25-OH vitamin D was also low (16.2 ng/mL, n30.0-100.0 ng/mL), with elevated 1,25-OH vitamin D (95 pg/mL, n15-75 pg/mL) and bone-specific alkaline phosphatase (118 u/L, n0-55 u/L). An ultrasound demonstrated a 3.5cm left inferior thyroid bed mass, with positive Tc-99m sestamibi uptake. MRI confirmed lytic vertebral brown tumors, as well as a T11 compression fracture.

The patient received IV bisphosphonate and was discharged after normalization of calcium, but was re-admitted one month later for recurrent hypercalcemia. He again received IV bisphosphonate while awaiting surgery, then underwent left parathyroidectomy with removal of a 17g adenoma. Intraoperatively, no stigmata of malignancy were identified and PTH fell 2499→124 pg/mL (down to 11pg/mL on POD #1). He was treated with IV calcium drip, oral calcium, cholecalciferol, and calcitriol for hungry bone syndrome; then titrated off the drip on POD #9 and discharged home on POD #12.

On follow-up, POD #13 PTH was increased to 104 pg/mL, rising to 131 pg/mL on POD #26 (with normal calcium and vitamin D levels). The patient declined spinal surgery for improving back pain, and otherwise remains asymptomatic. His PTH and calcium are being closely followed.

Conclusion:  Eucalcemic ePTH is common in patients after surgery for PHPT, and is associated with a 5.4% risk of PHPT recurrence. Advanced age, larger parathyroid mass, lytic bone disease (including brown tumors), higher pre-op PTH and alkaline phosphatase, recent bisphosphonates, and vitamin D deficiency can predispose patients to post-op ePTH. In patients with these risk factors, ePTH may represent an expected response to bone remineralization, changes in calcium-sensing and PTH receptors, and/or inadequate vitamin D supplementation. Such ePTH tends to peak 2-6 months post-op, and might slowly resolve or persist for years without PHPT recurrence.

(1) Lang, B.H., et al. (2012). “Eucalcemic parathyroid hormone elevation after parathyroidectomy for primary sporadic hyperparathyroidism: Risk factors, trend, and outcome.” Ann Surg Oncol 19(2): 584–590. (2) Ning, L., R. Sippel, et al. (2009). "What is the clinical significance of an elevated parathyroid hormone level after curative surgery for primary hyperparathyroidism?" Ann Surg 249(3): 469-472.(5) (3) Oltmann, S. C., N. M. Maalouf, et al. (2011). "Significance of elevated parathyroid hormone after parathyroidectomy for primary hyperparathyroidism." Endocr Pract 17 Suppl 1: 57-62.(4) Carsello, C. B., T. W. Yen, et al. (2012). "Persistent elevation in serum parathyroid hormone levels in normocalcemic patients after parathyroidectomy: does it matter?" Surgery 152(4): 575-581; discussion 581-573.(5) Khalil, P. N., S. M. Heining, et al. (2007). "Natural history and surgical treatment of brown tumor lesions at various sites in refractory primary hyperparathyroidism." Eur J Med Res 12(5): 222-230.(6) Agarwal, G., S. K. Mishra, et al. (2002). "Recovery pattern of patients with osteitis fibrosa cystica in primary hyperparathyroidism after successful parathyroidectomy." Surgery 132(6): 1075-1083; discussion 1083-1075.

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