Endocrine Abstracts

Introduction: Hypercalcemia of malignancy usually appears in patients with osteolytic metastasis and in those patients with humoral hypercalcemia due to secretion of PTHrp by the tumor. Hypercalcemia due to calcitriol production by the tumor is uncommon (<1% of cases of hypercalcemia of malignancy). It is the cause of virtually all cases of hypercalcemia in patients with Hodgkin’s lymphoma and approximately one third of cases in non-Hodgkin’s lymphoma. It has also been described in some cases of ovarian dysgerminoma.

Methods: We describe the case of a patient with MALT Non-Hodgkin lymphoma admitted to our hospital with severe hypercalcemia.

Results: Our patient was admitted to the hospital with calcium levels above 15 mg/dl. After hydration, loop diuretics and zoledronic acid he reached calcium level of 10.5–11 mg/dl but after withdrawal of intravenous hydration he presented recurrence of hypercalcemia up to the initial values. Analytics showed very low levels of PTHi and 25-OH-Vitamin D (5.76 pg/ml, 3 ng/ml respectively). Imaging tests (body CT) did not show osteolytic lesions suggestive of metastases. Given the suspicion of humoral hypercalcemia we initiated treatment with Cinacalcet 60 mg daily and steroids (Prednisone 1 mg/kg per day) without a satisfactory response in reducing calcium levels. Analytical result showed undetectable levels of PTH-related protein (<1.1 pmol/l) and very high calcitriol levels (148 pg/ml, N: 16–56 pg/ml). Our suspicion of calcitriol tumoral production associated with lymphoma is therefore confirmed. In view of the poor response to medical treatment and the need for intense hydration to maintain acceptable calcium levels a splenectomy with cytoreductive objective (19 cm splenomegaly) was performed. After this, calcium levels reached the normal level (9.5–10.2 mg/dl) and remained stable.

Conclusion: Although tumor production of calcitriol is an uncommon cause of hypercalcemia, it is usually related to lymphomas. We must think in this disorder in patiens with lymphoma and hypercalcemia.