I know that some people have to stop Lithium because of age, but 50 seems awfully young for that. I was once inpatient with a woman who was going mad after having to stop her Lithium. It had kept her stable for decades and then at age 70 she had to stop it. I do not recall whether she actually experienced kidney issues or her doctor took her off Lithium at 70 preventatively, but she sure was unhappy and in and out of inpatient stays.