Expert consensus on when to worry about renal decline and when to stay the course
STUDY: Strandhave C et al, International Journal of Bipolar Disorders 2026
STUDY TYPE: Expert consensus review and management algorithm
FUNDING: Independent
Background
In the 1970’s, dramatic reports of renal damage raised concerns about lithium’s safety. But those early reports could not prove causation, and bipolar itself is a risk factor for renal disease. Newer studies with better designs have provided more reassuring results, and here experts sort through the whole picture to arrive at consensus.
Renal Impairment, Not Failure
Lithium raises the rate of mild to moderate kidney disease (CKD stage 3), but not kidney failure. Few patients need dialysis, and that rate is similar to other mood stabilizers in direct comparisons.
Risk factors for renal impairment on lithium include female gender, chronic use, and:
- Medical disorders that impair renal function: Hypertension, diabetes, baseline albuminuria, prior renal injury
- Nephrotoxic medications: Chronic NSAIDs, ACE-inhibitors, angiotensin II receptor blockers, loop/thiazide diuretics
How to Minimize Risk
Higher levels mean higher risk. Mean lithium levels of 0.60–0.79 mmol/L are linked to approximately triple the risk of CKD stage 3-5, and levels of 0.80–0.99 mmol/L to roughly quadruple. Each episode above 1.0 mmol/L adds risk on top of that.
Dosing once daily (all at night) lowers the risk, and is feasible as lithium has close to a 24 hours half life.
N-Acetylcysteine
The paper does not mention n-acetylcysteine (NAC), likely because it lacks human studies in this specific issue. This antioxidant reduced renal injury after lithium toxicity in two animal studies, and has over a hundred human trials in renal disease. In humans, NAC slowed the progression of renal impairment and prevented damage from nephrotoxins, primarily contrast dye. However, not all trials were positive.
N-acetylcysteine is well-tolerated and has evidence to treat chronic, low-grade depression in bipolar disorder at a dose similar to those used in renal studies (2,000 mg daily). I often recommend it on lithium; here’s how to use it.
A New Term
Nephrogenic diabetes insipidus is now called arginine vasopressin resistance (AVP-R). It presents with massive amounts of very dilute urine (polyuria) and intense, constant thirst (polydipsia). It is an early warning sign of renal trouble on lithium, and treating it may reduce progression to renal disease.
They recommend treating AVP-R with amiloride (start 5 mg amiloride once to twice daily for 2 weeks then 10 mg once to twice daily). The recommend against spironolactone, which did not work in a studies of AVP-R and can raise lithium levels. Here is the full AVP-R algorithm:
Below are mechanisms of lithium toxicity. Tip: Valproate injures the kidneys through other mechanisms, and switching to valproate produced worse outcomes in a large, non-randomized study.
Lab Recommendations
Check creatinine and eGFR before starting lithium, then once or twice a year after that. See image at the top of this post for full monitoring algorithm.
If eGFR drops below 60, refer to nephrology, but don’t reflexively stop lithium as the risk of suicide and new mood episodes risks with rapid discontinuation (if tapering off, do so over at least a month, preferably a few months).
Once eGFR drops to around 30-40 mL/min, decline often keeps going even after stopping lithium, a point the authors call the renal “point of no return.” Stopping lithium at that point may not help the patient, but is a consideration if the eGFR is above that threshold.
—Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
