Session: MON 199-237-Disorders of Parathyroid Hormone & Calcium Homeostasis
Poster Board MON-222
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.
Nothing to Disclose: AEA, MEA, AMS
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