From the FDA Drug Label
Lithium should generally not be given to patients with ... severe debilitation or dehydration, or sodium depletion, ... since the risk of lithium toxicity is very high in such patients. The patient, RS, was dehydrated after being outside in hot summer weather, which increases the risk of lithium toxicity.
- Dehydration can lead to a decrease in renal function, which can cause lithium levels to rise.
- Therefore, it is likely that RS's lithium level is high due to dehydration. 1
From the Research
I would anticipate that RS's lithium level would increase significantly after dehydration and ibuprofen use, potentially reaching toxic levels. Dehydration reduces renal clearance of lithium by decreasing glomerular filtration rate, while ibuprofen (an NSAID) inhibits prostaglandin synthesis in the kidneys, which further reduces lithium excretion 2. This combination can cause lithium retention and elevate serum concentrations by 20-40% or more, even if the lithium dose remains unchanged. Some key points to consider in this scenario include:
- Dehydration can lead to increased lithium levels due to decreased renal clearance 3
- Ibuprofen can further reduce lithium excretion by inhibiting prostaglandin synthesis in the kidneys 2
- Symptoms of lithium toxicity may develop, including tremor, confusion, ataxia, vomiting, diarrhea, and in severe cases, seizures or coma 4, 5, 6
- Patients on lithium therapy should maintain adequate hydration, especially during hot weather or illness causing fluid loss, and should avoid NSAIDs like ibuprofen whenever possible 2
- If an NSAID is necessary, lithium levels should be closely monitored and the lithium dose potentially reduced 2
- Alternative pain relievers such as acetaminophen would be safer options as they don't significantly affect lithium levels 2