- It is done on the serum of the patient.
- The time to take the sample is 12 hours after the dose.
- It is used particularly in psychiatric patients on lithium therapy :
- Manic depressive illness (Bipolar affective disorder).
- The manic phase of the affective disorder.
- For the treatment and prevention of mania and people with bipolar disorders.
- This is present in the ultra-trace amount.
- Lithium is an element like sodium and potassium.
- Its salt may be found on earth in small quantities.
- The amount of river water and the well is very low.
- In plants and the animal, the tissue is also low.
Metabolism of Lithium
- There is the complete absorption of lithium from the GI tract.
- The peak level reaches within 2 to 4 hours after the intake of the drug.
- This is free in the blood and does not bind to the protein.
- The clearance in the blood is biphasic.
- First phase: 30 to 40 % cleared with a half-life of 22 hours.
- Second phase: The remainder lithium present in the ion pool is cleared with a half-life of 48 to 72 hours.
- The clearance is mainly dependant upon the renal function where active absorption occurs.
- Decreased renal function causes prolonged clearance time.
- Lithium carbonate is used as a drug to treat patients with bipolar manic depression.
- When given to patients then regulates the neurotransmission in the brain.
- The lithium level should be monitored very carefully because the Level for the therapeutic dose and toxic dose is very narrow.
- Therapeutic level = 0.8 to 1.2 meq/L (meq/L = mmol/L).
- Maintinance dose = 0.5 to 1.2 mmol/L.
- Toxic level = >2.0 meq/L
- There is a lab variation of these values from lab to lab.
- Decreased dietary sodium leads to a decrease in the excretion of lithium.
- Therapeutic level: 0.8 to 1.2 meq/L
- Toxic level : > 2.0 meq/L
- (meq/L = mmol/L, both values are the same)
- Acute mania = 0.6 to 1.2 meq/L
- Protection against future episodes in patients with bipolar disorder = 0.8 to 1.0 meq/L
- Toxic level = >2 meq/L
The side effects of the raised level of lithium:
|Clinical presentation||If the lithium level is|
|Gastrointestinal symptoms||1.5 to 2.0 meq/L|
|Tremors||1.5 to 2.0 meq/L|
|Somnolence||2.0 to 2.5 meq/L|
Stop the medicine when the patient feels the following signs and symptoms:
- The patient has dizziness, or drowsiness, or a lake of energy.
- There may be muscle weakness.
- The patient may have nausea, vomiting, or diarrhea.
- Difficulty in speech.
- There may be a lack of coordination.
- The patient may be confused.
- May get irregular tremors or shaking.
- There may be restlessness.
- The recommended time for the lithium estimation is 12 hours after the dose:
Mechanism of Lithium action
- This enhances the reuptake of catecholamines.
- So it decreases their concentration in the neuronal junction.
- This reduced level produces a sedation effect on CNS.
- Lithium also modulates the distribution of sodium, calcium, magnesium in the nerve cells.
- Also, regulate the glucose metabolism that affects the nerve function.
- The clearance is done by the kidneys. So in the case of renal damage, the clearance is delayed.
- Lithium is given to the patient as lithium carbonate.