Session: MON 199-237-Disorders of Parathyroid Hormone & Calcium Homeostasis
Poster Board MON-215
Clinical case: A 55 year old woman had a total thyroidectomy and a single dose of 104 mCi of RAI 16 years ago for a 3.5 cm follicular carcinoma of the thyroid. She had no evidence of residual thyroid cancer. Surgery was complicated by permanent hypoparathyroidism treated with calcium carbonate 600 mg BID, calcitriol 0.25 mcg qd, and cholecalciferol 800 units qd. For many years she had serum calcium levels in the low-normal range. In July, 2012 her calcium was 10.0 mg/dL (normal: 8.5-10.1) with an albumin of 4.1 g/dL (3.4-5.0). Doses of calcium and cholecalciferol were reduced by 50%, while calcitriol was continued at 0.25 mcg qd. At that visit she had a single 1 cm posterior cervical lymph node. 2 weeks later she presented with nausea, abdominal pain, and multiple, rapidly enlarging cervical and axillary lymph nodes which were matted and nontender. Testing disclosed a serum calcium of 13.3 mg/dL, albumin 3.1 g/dL (corrected calcium 14), phosphorus 2.6 mg/dL (2.5-4.9), PTH <1 pg/mL (12-88), 25(OH) vitamin D 24.9 ng/mL (30-100), and 1,25(OH)2 vitamin D 121.8 pg/mL (10-75). Chest CT revealed cervical, axillary, mediastinal adenopathy and splenomegaly. An axillary lymph node biopsy was diagnostic for a diffuse B cell lymphoma. Calcium and calcitriol were stopped and hypercalcemia was corrected with i.v. fluids.
PET/CT scan demonstrated widespread metastases to spleen, multiple lymph nodes, and bones, consistent with a stage IV, high grade, aggressive lymphoma. 7 weeks following treatment with intrathecal methotrexate and R-CHOP she had an excellent clinical response and developed recurrent hypocalcemia. PET/CT documented near complete resolution of the lesions. 12 weeks post therapy her calcium was 7.7 mg/dL, albumin 3.2 g/dL, 25(OH) vitamin D 29.2 ng/mL, and the 1,25(OH)2 vitamin D decreased to 39.2 pg/mL.
Conclusion: This is an unusual presentation of hypercalcemia due to a lymphoma producing 1,25(OH)2 vitamin D in a patient who had permanent postsurgical hypoparathyroidism. Clinicians should have a high index of suspicion for malignancy when patients presents with rapid and high elevations of serum calcium.
Nothing to Disclose: VS, SNL
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