New safety information for lithium drugs and the risk of high blood calcium and hyperparathyroidism

Issue

Health Canada is informing health professionals and patients of new safety information and treatment recommendations regarding the drug lithium and the risks of high blood calcium (hypercalcemia) sometimes associated with a hormone disorder known as hyperparathyroidism. Lithium is used widely to treat mania, a psychiatric condition that is part of bipolar disorder (manic-depressive illness). It has been available in Canada for over 60 years. It is used to treat acute manic episodes, and as a long-term therapy to reduce their frequency and severity. There is evidence that lithium affects the metabolism of calcium, which is already noted in the product labelling for lithium drugs. Lithium therapy may cause high levels of calcium in the bloodstream which may or may not be accompanied by an increased level of parathormone (also known as hyperparathyroidism).Blood calcium levels can be monitored by your doctor through regular blood tests before starting and during lithium therapy to ensure that any increases are identified. While in many cases the effects of high blood calcium and/or parathormone are unnoticeable or mild, in severe cases they can be life threatening. Severe hypercalcemia can be a medical emergency as coma and cardiac arrest can occur. Health Canada is currently working with the companies to update the product labels for lithium drugs to include new warnings with respect to the risk of hypercalcemia and hyperparathyroidism, and the need to consider calcium monitoring before and during lithium therapy. There are currently seven lithium-containing medications available in Canada: Apo-Lithium Carbonate, Carbolith, Lithane, Lithmax, Phl-Lithium Carbonate, Pms-Lithium Carbonate, Pms-Lithium Citrate. The benefits of this drug in the treatment of bipolar disorder, a serious mental illness, continue to outweigh the known risks of this drug.

What you should do

• Talk to a healthcare professional regarding any questions or concerns you may have about your lithium treatment.
• Tell your doctor if you experience symptoms of hypercalcemia, which include: fatigue, depression, mental confusion, nausea, vomiting, excessive thirst, appetite loss, abdominal pain, frequent urination, muscle and joint aches, and muscle weakness.
• Do not stop lithium treatment unless you have discussed the benefits and the risks of your treatment with your doctor.
• A number of blood tests are required as part of lithium treatment. Your doctor may include calcium and / or parathormone blood tests among these before and during treatment.