Lithium Test: Uses, Normal Range & Toxicity Symptoms

Overview

The Lithium Test, also called the Lithium Blood Level Test, measures the amount of lithium present in the bloodstream. Lithium is a mood-stabilizing medication commonly prescribed for:

• Bipolar disorder
• Depression (as an add-on treatment)
• Schizoaffective disorder
• Sometimes schizophrenia

Lithium is highly effective for stabilizing mood and reducing manic and depressive episodes. However, it has a very narrow therapeutic range, meaning:

✅ Too little → Symptoms return
❌ Too much → Toxic and dangerous

Because the difference between a helpful dose and a harmful dose is small, regular monitoring through a lithium test is essential. This test helps doctors check whether the lithium level is safe, effective, and appropriate for the patient.

Is Lithium Produced in the Body?

No. Lithium is not naturally made in the human body. It is a naturally occurring element found in the environment but is only taken into the body through prescribed medications, such as:

• Lithium carbonate
• Lithium citrate
• Lithium chloride

After taking the medication:

1. Lithium is absorbed through the stomach and intestines
2. It enters the bloodstream
3. It is filtered and removed mainly by the kidneys

Because the kidneys play a major role in lithium removal, any kidney problem can cause lithium levels to rise, increasing the risk of toxicity. This is one of the key reasons why monitoring is required.

Why Is the Lithium Test Important?

Lithium therapy must be personalized. People differ in how they absorb, process, and eliminate lithium. The test helps:

1. Check if the Dose Is Correct

The test confirms that lithium levels are within a safe and effective range.

2. Ensure Effective Mood Stabilization

If levels are too low, symptoms of bipolar disorder or depression may return.

3. Prevent Toxicity

High lithium levels can harm the brain, kidneys, and nervous system.

4. Guide Dose Adjustments

Doctors may adjust the dose if:

• The patient is elderly
• Kidney function changes
• Other medications are added
• The patient becomes dehydrated
• The patient becomes pregnant

5. Monitor Long-Term Treatment

Since many people stay on lithium for years, periodic testing ensures ongoing safety.

Causes of Low Lithium Levels

Lithium may be too low in the blood due to:

• Missing doses
• Taking a lower dose than prescribed
• Gastrointestinal problems reducing absorption
• Medications that increase lithium clearance, such as:
  • Caffeine
  • Theophylline
  • Some diuretics
• Increased kidney excretion
• Excess fluid intake

Symptoms of Low Levels

When lithium levels drop too low, symptoms of the mood disorder may return:

• Mood swings
• Irritability
• Increased energy or hyperactivity
• Depressive symptoms
• Poor sleep
• Difficulty concentrating
• Manic or hypomanic episodes

Low levels themselves do not harm the body—but uncontrolled mood episodes can be serious.

Causes of High Lithium Levels

Lithium levels may rise due to:

• Taking higher doses than prescribed
• Dehydration (less fluid = slower kidney clearance)
• Kidney impairment
• Drug interactions, especially:
  • NSAIDs (e.g., ibuprofen, naproxen)
  • ACE inhibitors (blood pressure meds)
  • Thiazide diuretics
• Very low salt intake
• Accidental or intentional overdose

Because lithium clearance depends on kidney function and sodium balance, sudden changes in hydration or salt intake can shift lithium levels quickly.

Symptoms of High Lithium (Lithium Toxicity)

Lithium toxicity is a medical emergency.

Early Signs

• Nausea
• Vomiting
• Diarrhea
• Tremors
• Muscle weakness
• Drowsiness
• Tiredness

Moderate to Severe Toxicity

• Confusion
• Slurred speech
• Blurred vision
• Unsteady walking
• Severe tremors
• Agitation
• Seizures
• Kidney damage
• Loss of consciousness
• Coma
• Risk of death if untreated

Anyone showing these symptoms should seek urgent medical care.

Reference / Therapeutic Range

Typical target range:

• 0.6 – 1.2 mmol/L

Levels above:

• > 1.5 mmol/L → Usually considered toxic

However, the ideal range depends on:

• Age
• Type of mood disorder
• Acute mania vs maintenance therapy
• Kidney function
• Other medications

Doctors adjust goals individually.

Sample Type and Timing

• Serum (blood sample) collected from a vein

Best time to test

Blood is usually drawn 12 hours after the last dose, known as the:

Trough level

This gives the most accurate reading of the lowest blood concentration before the next dose.

Who Should Get a Lithium Test?

Testing is recommended for:

• Patients starting lithium treatment
• Patients changing dose
• People with kidney problems
• Elderly patients
• Dehydrated patients
• Individuals on interacting medications
• Pregnant women on lithium
• People showing toxicity symptoms
• Those with poor treatment response

Long-term users often require testing every 3–6 months, or more frequently if needed.

Other Tests Done Alongside

Doctors may also order:

• Kidney function tests (creatinine, eGFR)
• Thyroid tests
• Electrolytes (sodium)
• ECG in older patients

Lithium can affect the thyroid and kidneys, so ongoing monitoring is important.

Test Preparation

• Usually no fasting required
• Take the medication as prescribed unless told otherwise
• Stay hydrated
• Do not change salt intake suddenly
• Inform your doctor if:
  • You missed doses
  • You are pregnant
  • You take NSAIDs or diuretics
  • You have vomiting, diarrhea, or dehydration

When to Consult a Doctor

Seek medical help if you:

• Notice worsening mood symptoms
• Experience tremors or extreme drowsiness
• Have vomiting or diarrhea
• Feel confused or disoriented
• Have kidney disease and start new symptoms
• Miss multiple doses
• Suspect overdose

Call emergency services if:

• You have seizures
• You lose consciousness
• You have breathing difficulty

Lithium toxicity requires urgent treatment.

Important Word Explanations

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