Hypocalcemia is a common clinical occurrence and has many potential causes, one of which can be congenital or acquired hypoparathyroidism. Acquired hypoparathyroidism is most commonly the result of damage to the glands, usually to their blood supply, during thyroidectomy, parathyroidectomy, or radical neck dissection. We present the case of a 40-year-old female known with Waldenström macroglobulinemia, cronic hepatitis C, who has been diagnosed with Graves disease and associated ophtalmopathy in 2004 and treated with antithyroid drugs for 1.5 years; a decision of total thyroidectomy was made considering the complexity of comorbidities and the fact that the patient already had a relapse under methymazol treatment. The postsurgical evolution was impeared by a sever hypocalcemia, necessitating repeted parenteral calcium administration associated with p.o. calcium and vitamin D, with rapid recovery, seric calcium beeing kept in normal limits and without symptoms.