Calcium of 19mg/dL and Yet Asymptomatic

Lithium is a commonly used medication for Bipolar disorder. Lithium induced hyperparathyroidism is a rare disorder but leading cause of hypercalcemia in patients receiving Lithium treatment. Lithium may lead to exacerbation of pre-existing hyperparathyroidism or it may increase set point for calcium for PTH suppression. We present a case of 65 year old female presented with hypercalcemia of 19mg/dl. She was sent by PCP office for hypercalcemia. She did not have any complains and was completely asymptomatic. Her history includes hypertension, Bipolar disorder and Diabetes mellitus type 2. She has not been able to get her labs drawn because of COVID-19. She was only having Tele visits with Psychiatrist. Her mood and bipolar symptoms were under controlled. She denies any abdominal pain, headache, visual problems, polyuria, polydipsia, numbness or tingling. She was given IV fluids and calcium was monitored. Her PTH was 65mg/dl, CBC and metabolic panel normal otherwise. Her Sestamibi scan was negative for parathyroid adenoma. Her lithium level was 4mg/dl. Lithium was discontinued after Psychiatry consultation. Her calcium came down to 9mg/dl after aggressive fluid resuscitation. Her calcium, parathyroid and lithium levels were monitored for next 6 months. Given her asymptomatic course she was not started on any calcium lowering medication. Her lithium level normalizes after one year of abstinence. A patient who is started on Lithium therapy should be monitored for hypercalcemia, hyperparathyroidism and nephrogenic diabetes.