Nolen WA, et al. - For lithium for maintenance treatment of bipolar disorder, researchers systematically reviewed existing trials on optimal serum levels and sought to develop clinical recommendations on this topic. A consensus was defined as statements endorsed by at least 80% of the members. They could not select any study with strict inclusion criteria. After loosening the inclusion criteria, they selected 7 trials addressing these aims at least to some extent. Outcomes support the standard lithium serum level of 0.60-0.80 mmol/L for adults with bipolar disorder; in case of good response but poor tolerance, the level could be reduced to 0.40-0.60 mmol/L, and in case of insufficient response and good tolerance, the level could be increased to 0.80-1.00 mmol/L. They identified no consensus for children and adolescents, however, most members endorsed the same recommendation. Also, they identified no consensus for the elderly, however, most members endorsed a more conservative approach, which was usually 0.40-0.60 mmol/L, with the option to go to maximally 0.70 or 0.80 mmol/L at ages 65-79 years, and to maximally 0.70 mmol/L over age 80 years.