Lithium is a metal, but in medicine, it is used to treat bipolar disorder and refractory depression. Refractory depression means depression that failed other recommended medical management. Lithium is excreted through the kidneys, therefore, your patient must have a normal renal function if you want to initiate lithium therapy. It has a very narrow therapeutic range, that is 0.4 – 1.0 mmol/L, if the lithium level in blood increases beyond 1.5mmol/L then the signs and symptoms of toxicity start to appear.
Signs and symptoms of lithium toxicity are;
- Coarse tremors
- Exagerated reflexes
- Confusion / Drowsiness
- Seizure
- Coma
Causes of lithium toxicity, other than over dosage and renal insufficiency are given below;
- Diuretic therapy especially bendroflumethiazide
- Dehydration due to any cause
- ACE inhibitors
- Metronidazole
Management of Lithium Toxicity.
Volume resuscitation with normal saline is the first step if your patient has adequate urine output. Monitor urine output, if your patient is in the coma then consider a central line to measure the central pressure that will guide fluid resuscitation in the absence of adequate urine output.
In case of severe toxicity, hemodialysis should be done without delay.
Sodium bicarbonate increase the renal excretion of lithium can be used under special circumstances for example if hemodialysis can’t be done due to unavailability or contraindication, but the evidence is limited.
