Renal tubular function in patients on long-term lithium therapy

Area of Science:

• Nephrology
• Psychiatry
• Pharmacology

Background:

• Long-term lithium therapy is a cornerstone treatment for recurrent affective disorders.
• Potential renal side effects, including impaired concentrating ability, are a concern with lithium use.

Purpose of the Study:

• To evaluate renal tubular concentrating and acidification function in patients on long-term lithium therapy.
• To investigate the relationship between erythrocyte lithium concentration and renal function.

Main Methods:

• Study included 10 unselected patients with recurrent affective disorders on long-term lithium therapy.
• Renal tubular concentrating ability was assessed by maximum urinary osmolality.
• Renal tubular acidification ability was evaluated.

Main Results:

• All patients demonstrated normal renal tubular concentrating ability, despite symptoms like polyuria and nocturia.
• All patients exhibited normal renal tubular acidification.
• A significant positive correlation was observed between erythrocyte lithium concentration and maximum urinary osmolality.

Conclusions:

• Long-term lithium therapy, even with symptoms of polydipsia and polyuria, does not appear to compromise renal tubular concentrating or acidification functions in this cohort.
• Higher erythrocyte lithium levels may be associated with preserved or enhanced urinary concentrating capacity.