Avoiding and treating lithium neurotoxicity
Gurpreet Singh, M.D., Pramod Kayathi, M.D., Vivek C. Shah, M.D., Steven Lippmann, M.D.
LITHIUM
Patient education and physician awareness during lithium pharmacotherapy can usually avoid lithium neurotoxicities. Careful prescribing with clinical monitoring facilitates safe practice. Serum lithium levels within therapeutic ranges provide evidence of appropriate treatment, and deviations from this regimen require explanatory documentation. Always consider renal, cardiac, general health status, and hydration factors while prescribing. Lithium clearance progressively declines with age and/or kidney dysfunction. Serum concentrations are standardized for assessment interpretation 12 hours after last dosing.
SAFETY
Inform patients and their family about drug-drug interactions, particularly about lithium retention with sodium-wasting diuretics like hydrochlorothiazide. Retention is also induced by angiotensin-converting enzyme inhibitor drugs and non-steroidal anti-inflammatory agents. On rare occasions when co-prescribed with antipsychotic medications or dopamine antagonists, neuroleptic malignant syndrome can present. Stress maintaining stable hydration and avoiding dehydration. Neurotoxic signs and symptoms sometimes occur at sub-therapeutic serum levels, but with steady concentrations near 1.5 mEq/L, they are more clinically significant. At levels consistently over 2.5mEq/L, dangerous toxicity might present with neurological damage, especially at inducing profound cerebellar dysfunction. Compromised coordination can become a permanent disability. Once lithium passes the blood-brain barrier into the central nervous system, clearance out of the brain is slow, and thus, concentrations there may be higher than are reflected by assays in blood samples.
MANAGMENT
Mild lithium intoxication is managed by administration of copious oral fluids and electrolytes. Cathartics and gastric lavage with charcoal are occasionally considered. Moderate toxicity mandates intravenous fluids and electrolyte repletion. Serious toxicity is remediated by very promptly instituting hemodialysis. Timely, aggressive utilization of these measures can diminish neurotoxicity. The duration of intervention should be maintained until disappearance of clinical toxicity, beyond that of just sustained low serum lithium levels. The goal is to prevent discomfort and long-term brain damage.