This practical handbook provides clinicians with a detailed explanation of lithium's renal journey, how this informs our understanding of polyuria pathogenesis and how medications or hyponatremia can alter lithium clearance. Covering efficacy, pharmacokinetics, toxicity, discontinuation, and use in special patient groups including pregnant and breastfeeding women, older or younger patients, each section also provides a detailed background for its suggested logical approach to managing lithium's renal and other adverse effects.