Which mood stabilizer is completely renally eliminated?

Lithium is the mood stabilizer that is completely renally eliminated. It is primarily excreted through the kidneys, with most of the drug being eliminated in the urine. This property is crucial for clinicians to consider, especially since lithium has a narrow therapeutic index. Regular monitoring of kidney function is essential for patients on lithium therapy to avoid toxicity.

In contrast, valproic acid and carbamazepine are primarily metabolized by the liver, where they undergo hepatic metabolism before being excreted, indicating that they are not entirely eliminated through the kidneys. Risperidone, an atypical antipsychotic, also undergoes significant hepatic metabolism, with renal elimination accounting for only a portion of the drug clearance. Thus, the renal elimination of lithium makes it unique among the listed options and highlights the importance of renal function monitoring in patients receiving lithium treatment.