Lithium is a long-term treatment used clinically for bipolar disorder. Lithium has a narrow therapeutic/toxic ratio and maintaining patients within the appropriate therapeutic margin requires scheduled monitoring. A NPSA alert in Dec 2009 (NPSA/2009/PSA005) states that all prescribers check that blood tests are monitored regularly and it is safe to issue a repeat prescription. The monitoring should be in line with NICE guidance i.e. Lithium blood level measured every three months as standard, renal function tests and thyroid function tests every six months. In addition, yearly health checks and monitoring of weight are recommended.