Author: Rachel Brady, MD Educational Pearls: Hypercalcemia of malignancy: Hypercalcemia of malignancy can present with lethargy, muscle weakness, hyperreflexia, altered mental status, cardiac dysrhythmias, and even cardiac arrest. Treatment is based both on calcium level and symptoms Intravenous rehydration is first line treatment Other options include steroids, bisphosphonates and calcitonin.  Tumor Lysis Syndrome Occurs due to the breakdown of tumor cells after chemotherapy/radiation Presents as hyperkalemia, hyperuricemia, hyperphosphatemia, and hypocalcemia Treatment is very similar to severe hypercalcemia - hydration with crystalloids Hyperuricemia can be treated using rasburicase or allopurinol   References: Ñamendys-Silva SA, Arredondo-Armenta JM, Plata-Menchaca EP, Guevara-García H, García-Guillén FJ, Rivero-Sigarroa E, Herrera-Gómez A. Tumor lysis syndrome in the emergency department: challenges and solutions. Open Access Emerg Med. 2015 Aug 20;7:39-44. doi: 10.2147/OAEM.S73684. eCollection 2015. Review. PubMed PMID: 27147889; PubMed Central PMCID: PMC4806807. Zagzag J, Hu MI, Fisher SB, Perrier ND. Hypercalcemia and cancer: Differential diagnosis and treatment. CA Cancer J Clin. 2018 Sep;68(5):377-386. doi: 10.3322/caac.21489. Epub 2018 Sep 21. Review. PubMed PMID: 30240520.   Summary by Travis Barlock, MS4  | Edited by Erik Verzemnieks, MD