Hemodialysis in lithium poisoning: what is the evidence?
January 23, 2015, 11:59 pm
Extracorporeal Treatment for Lithium Poisoning: Systematic Review and Recommendations from the EXTRIP Workgroup. Decker BS et al. Clin J Am Soc Nephrol 2015 Jan 12 [Epub ahead of print]
The purpose of this review, from the Extracorporeal Treatments in Poisoning (EXTRIP) workgroup, was to give evidence-based recommendations related to use of hemodialysis and other extracorporeal modalities in the treatment of lithium toxicity.
The goal of enhanced elimination in lithium poisoning is to avoid the syndrome of irreversible lithium-effectuated nerutoxicity (SILENT), which causes persistent cerebellar dysfunction after prolonged exposure of the CNS to high levels of lithium.
Using elaborate methodology, the EXTRIP group reviewed relevant literature, identifying 166 papers (describing 228 patients) in multiple languages that merited inclusion. Most of these were case reports yielding, in the words of the authors, “a very low quality of evidence for all recommendations.” In other words, there is no real evidence, and the recommendations and (weaker) suggestions are based mostly on the opinions of the workgroup members.
Now, the EXTRIP group is comprised of some very smart clinicians from a variety of specialties, including medical toxicology, nephrology, and intensive care. Their opinions are definitely worth reading and considering carefully. For example, this is a summary of their proposed indications for extracorporeal treatment (ECTR – read hemodialysis) in lithium poisoning:
- ECTR is recommended
- if kidney function is impaired [serum creatinine > 2.0 mg/dL in adults or 1.5 mg/dL in the elderly] and lithium > 4.0 mEq/L
- if there is decreased level of consciousness, seizures, or life-threatening dysrhythmias regardless of lithium level
- ECTR is suggested:
- if lithium level > 5.0 mEq/L
- if there is confusion
- if the expected time to reach lithium level < 1.0 mEq/L with optimal management is greater than 36 h
There are a number of problems with this list. Most importantly, I think, is that it considers hemodialysis in isolation without integrating the modality in the total care of the patient and other possible treatments. For example, if an adult took an acute lithium overdose and presented with a serum lithium level of 4.1 mEq/L and at serum creatinine of 2.1 mg/dL, but without signs or symptoms of toxicity, would it not be reasonable to administer fluids, observe carefully, and recheck levels in several hours? And if that makes sense, what if the lithium was 4.2 and the creatinine 2.2? Would the speculative potential benefit of hemodialysis in this situation outweigh the small chance of possible risks? Clinical judgment is still required, and strict cut-off criteria seem artificial — and certainly not evidence-based.
Some toxicologists have objected that the recommendations seem not to make a distinction between acute, chronic, and acute-on-chronic exposure. I think the authors would argue that inclusion of symptoms in their recommendations (if not in their weaker “suggestions”) corrects for not considering the pattern of exposure, and that the most important thing is whether the drug is in the CNS, not how it got there.
In any case, there are many pearls about lithium toxicity in this article, and it is well worth reading. Just take the recommendations with a grain of salt — but not a salt substitute.