Hypocalcemia in Malignancy - Unexpected but Common

One of the most common metabolic abnormalities found in patients with malignancy is hypercalcemia. Hypocalcemia is a rare occurrence and is often found to be associated with renal failure and patients taking bisphosphonate therapy for bone metastasis in this patient population. Here, we present two different case reports with hypocalcemia. A 66-year-old female with a recent diagnosis of tonsillar diffuse B-cell lymphoma admitted with complaints of generalized weakness after one cycle of R-CHOP, found to have neutropenia, a low calcium level, high PTH, and low 25-hydroxy Vitamin D levels. She was given calcium gluconate and supplemental 25-hydroxy Vitamin D. On day 2, the patient's symptoms and counts improved. The second patient was a 64-year-old male with recurrent metastatic laryngeal carcinoma, along with a second locally advanced primary rectal adenocarcinoma, presented with severe hypocalcemia and a low PTH level. The patient was on adjuvant chemotherapy and exhibited Chvostek's sign, along with perioral numbness, tingling, and twitching sensations, which eventually led to dysphagia. He was treated with calcium gluconate, calcitriol, and calcium carbonate. Signs and symptoms, along with lab values, improved on day 4. These cases suggest that calcium kinetics and 25-hydroxy Vitamin D levels need to be monitored in these patient populations in a routine manner.