[Lithium and its impact on renal function. Recommendations for practice, especially for older patients]

Despite its substantial therapeutic efficacy-particularly in the acute treatment and relapse prevention of bipolar affective disorders-lithium is associated with a broad spectrum of side effects, among which potential nephrotoxicity represents one of the most significant long-term risks. In clinical practice, particularly in the treatment of older adults, physicians are often faced with the question of whether lithium therapy can or should be continued, or whether initiation is feasible, given comorbid somatic illnesses, polypharmacy, or reduced glomerular filtration rate (GFR). The aim of this review is to provide practical, evidence-based recommendations for clinical decision-making.

A comprehensive literature search was conducted using PubMed, Web of Science, and Google Scholar, focusing on the treatment of patients with bipolar and unipolar affective disorders with lithium and its potential effects on renal function, particularly in the context of long-term therapy and aging. A case report is included to illustrate clinical application.

Lithium remains a cornerstone in the pharmacological treatment of bipolar and unipolar affective disorders, despite its known nephrotoxic potential. Optimizing the balance between therapeutic benefit and potential renal risks necessitates close monitoring and individualized treatment adjustments. The risk of lithium-induced nephropathy increases with the duration of therapy, patient age, and the frequency of episodes of lithium toxicity or overdose. Current guidelines recommend maintaining serum lithium levels within a range of 0,6-0,8 mmol/L. In older patients with good treatment response, target levels at the lower end of the therapeutic window (0,4-0,6 mmol/L) are advised. Lithium therapy should be monitored at regular intervals, including laboratory testing and 12-hour serum level checks every three months, or every 8-10 weeks in elderly patients. If GFR falls below 30 ml/min/1,73 m², nephrology consultation is warranted, and the continuation of lithium treatment should be critically re-evaluated. In patients with a GFR below 45 ml/min/1,73 m², initiation of lithium therapy in old age is not recommended. Decisions regarding the discontinuation or initiation of lithium therapy should always be made on an individual and interdisciplinary basis, carefully weighing the therapeutic benefit against the risk of affective relapse and the potential for progressive renal impairment.