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Sunday, June 19, 2011

Effects of Lithium toxicity

Lithium is a medication prescribed for bipolar affective disorder and resistant depression. It has one of the simplest structure (in ionized form an atom), but has quite complex mechanism of action. In addition, it is also a toxic metal to the human body. But toxicity occurs when the blood lithium levels reach a critical level.
Usually Lithium should be taken in higher dose for some time to get lithium toxicity. It is unlikely to get lithium toxicity when single large dose of lithium is taken.

However, critical level that is needed to produce toxicity and the level that is needed to achieve symptom control is within a narrow margin. Therefore, it is important to take the drug as prescribed, take adequate amounts of water and do regular lithium levels in the blood (at least every six months). In addition, it is important to know the early features of lithium toxicity and get medical attention before full blown toxicity sets in.

What are the important lithium levels?
Lithium levels should be monitored after 12 hours of last dose. If the patient is on twice daily dosing then blood should be taken just before the morning dose of the day (Lithium is usually prescribed once or twice a day). Blood should be collected to a plain bottle and carried to the laboratory.

Lithium normal therapeutic range
0.6 - 1.2 mmol/l

Early toxicity
> 1.5mmol/l

Life threatening toxicity
>2.0 mmol/l

How to prevent lithium toxicity?

Lithium levels should be tested at least every six monthly in a patient with stabilized regimen. In addition, patients should not take NSAID pain killers, ACE inhibitors, and Diuretics without expert advice. It is important to note that they should not take over the counter NSAID pain killers such as Aspirin and Motrin.

Effects of lithium on organs


1. Kidney failure – 1% of patients develop irreversible kidney damage on long term use (after 10 years of treatment).
a. Around 10% develop structural kidney changes
2. Hypothyroidism: Around 5 -35% develops reversible thyroid gland failure. But treatment with thyroxin can alleviate the symptoms.
3. Effects on the developing baby: Lithium is known to cause heart anomalies in the newborn, if taken during pregnancy. There is 400 fold rises in the incidence of Ebstein anomaly of the heart.


What are the symptoms of Lithium Toxicity?


Early signs

1. Marked tremors,
2. Anorexia, Nausea/Vomiting,
3. Diarrhea, and lethargy


Late signs

1. Restlessness
2. Muscle fasciculation’s/jerks
3. Abnormal movements
4. Severe drowsiness
5. Confusion
6. Reduced blood pressure
7. Heart rhythm abnormalities
8. Fits


What are side effects of Lithium therapy?

Side effects are different from toxic effects. It is because side effects can occur within lithium normal dosage range. They are not usually dangerous.

Warning and disclaimer
This articles is for the information only. You should not take or discontinue lithium without your doctors advice.


Sources
New Oxford textbook psychiatry

First published in
Mental health information blog





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