Lithium

What sample is needed for Lithium?

1. It is done on the patient’s serum.
2. The sample should be taken 12 hours after the dose.

What are the indications for Lithium?

1. It is used mainly in psychiatric patients on lithium therapy :
   1. Mania.
   2. Manic depressive illness (Bipolar affective disorder).
   3. The manic phase of the affective disorder.
   4. For the treatment and prevention of mania and people with bipolar disorders.

How will you define Lithium?

1. Lithium, known as Eskalith or Lithane, Lithonate as lithonate carbonate, is given for treating the manic phase of mania, affective disorder, and manic depressive disease.
2. This is present in ultra-trace amounts.
3. Lithium is an element like sodium and potassium.
4. Its salt may be found on Earth in small quantities.
5. The amount of lithium in river water and wells is very low.
6. In plants and animals, the tissue levels of lithium are also low.

What is the mechanism of action of lithium?

1. It is postulated that lithium helps in the reuptake of catecholamines, decreasing their concentration in the neuronal junction.
2. This reduction of catecholamines at the neuronal junction produces a sedative effect on the central nervous system.
3. Lithium also regulates the distribution of sodium, calcium, and magnesium in the nerve cells, reducing glucose metabolism that affects nerve function.
4. Also, it regulates glucose metabolism, which affects nerve function.
5. The kidneys do the clearance. So in the case of renal damage, the clearance is delayed.

What is the mechanism of absorption of Lithium?

1. Lithium is completely absorbed from the GI tract.
2. The peak level is reached within 2 to 4 hours after the intake of the drug.
3. This is free in the blood and does not bind to proteins.
4. The clearance in the blood is biphasic.
5. First phase:
   1. 30% to 40% is cleared with a half-life of 22 hours.
6. Second phase:
   1. The remainder of lithium present in the ion pool is cleared with a half-life of 48 to 72 hours.
7. Clearance mainly depends on renal function, where active absorption occurs.
8. Lithium passes through the glomerular membrane and is reabsorbed in the proximal convoluted tubules.
9. In case of dehydration, fever, watery stool, vomiting, and hot weather, the risk of lithium intoxication is increased.
   1. In dehydration, the proximal tubular response to reabsorption of sodium and lithium is reduced clearance.
10. The decreased renal function causes prolonged clearance time.

11. Lithium carbonate is used as a drug to treat patients with bipolar manic depression.
    1.   When given to patients, it regulates neurotransmission in the brain.

What is the therapeutic dose of Lithium?

1. The lithium level should be monitored very carefully because the Level for the therapeutic and toxic doses is very narrow.
   1. Therapeutic level =  0.8 to 1.2 meq/L (meq/L = mmol/L).
   2. Maintenance dose = 0.5 to 1.2 mmol/L.
   3. Toxic level = >2.0 meq/L

2. The standardized 12-hour postdose serum lithium concentration should be assessed as an adequate dose.
   2. The optimum level is 1.0 to 1.2 mmol/L (therapeutic dose).
   3. The concentration of lithium 1.2 to 1.5 mmol/L is the warning range.
   4. A lithium level >1.5 mmol/L in a 12-hour post-dose suggests a risk of intoxication.
3. There is a lab variation of these values from lab to lab.
4. Decreased dietary sodium leads to decreased lithium excretion.

What is the effect of toxic doses of lithium?

1. Lithium concentration of >2.5 mmol/L indicates severely intoxication by:
   1. Muscle rigidity.
   2. Hyperactive deep tendon reflexes.
   3. Epileptic seizures.

When to stop the Lithium?

1. The patient has dizziness, drowsiness, or a lack of energy.
2. Muscle weakness and ataxia may occur.
3. The patient may have nausea, vomiting, or diarrhea.
4. Difficulty in speech.
5. There may be a lack of coordination.
6. The patient may be confused.
7. May get irregular tremors or shakes.
8. There may be restlessness.
9. There may be myoclonic twitching.
10. There may be life-threatening seizures.
11. Lithium excretion is parallel to sodium excretion.

When to check the Lithium level and other blood tests?

1. The recommended time for the lithium estimation is 12 hours after the dose.
2. It is tested by flame photometry.
3. Usually, lithium level is checked once a month for maintenance.
4. RBC lithium level is better than the serum level. RBC levels are more stable because of the short half-life of Lithium in the serum.
5. Also, renal function and thyroid function should be checked along with lithium levels.
   1. TSH level is increased in 30% of the cases.
   2. Lithium decreases testosterone levels.
6. Recommended blood  screening tests:
   1. Sodium, Potassium, Calcium, and phosphate.
   2. Renal parameters like BUN and creatinine.
   3. Thyroid function tests like TSH and T4.
   4. Urine analysis (specific gravity and osmolality).
   5. Complete blood count (CBC).

What are the normal values of Lithium?

Source 2 

• Therapeutic level: 0.8 to 1.2 meq/L
• Toxic level :  > 2.0 meq/L
• (meq/L = mmol/L, both values are the same)

Source 4

• 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

What drugs increase the Lithium levels?

1. Indomethacin.
2. Diclofenac.
3. Hydrochlorothiazide.

What drugs decrease the Lithium level?

1. Theophylline.
2. Acetazolamide.
3. Sodium bicarbonate.
4. Urea.
5. Spironolactone.
6. Aminophylline.

What are the side effects of the raised level of lithium?

How will you treat patients with Lithium?

• Lithium is given to the patient as lithium carbonate.

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