What is the Olanzapine test?

The Olanzapine test measures the concentration of olanzapine, an atypical antipsychotic medication, in the bloodstream. Olanzapine is commonly prescribed for conditions such as schizophrenia and bipolar disorder and may also be used in other psychiatric indications.

Blood level testing helps assess whether the medication is within the expected therapeutic range. Because individuals metabolise olanzapine differently, monitoring supports personalised dosing and reduces the risk of adverse effects.

Why do I need an Olanzapine test?

Therapeutic drug monitoring can be helpful when response or tolerance to treatment is uncertain.

You may need this test if you:

• Are starting olanzapine or changing dose

• Have limited response to treatment

• Experience side effects such as sedation or weight gain

• Require adherence assessment

• Are taking interacting medications

• Have liver function concerns

• Need long-term treatment monitoring

The test helps ensure medication levels are appropriate for your individual metabolism.

Benefits of the test

1. Supports safe olanzapine dosing
   Helps avoid under- or over-exposure.

2. Reduces side-effect risk
   Identifies potentially high drug levels.

3. Supports treatment optimisation
   Aids dose adjustment decisions.

4. Useful in non-response assessment
   Helps distinguish dose from resistance issues.

5. Monitors adherence objectively
   Confirms medication exposure.

6. Simple blood-based testing
   Requires only one blood sample.

7. Widely used in psychiatric care
   Standard therapeutic drug monitoring approach.

8. Supports long-term treatment safety
   Useful during ongoing therapy.

Step-by-step: How we offer testing

Clinic-based testing (UK-wide)

• Choose your nearest UK clinic

• Attend your appointment

• Blood sample taken by a clinician (timed relative to dosing if required)

• Sample sent to the laboratory

• Results issued once analysis is complete

Home or hotel visit (+£60, UK-wide)

• Mobile phlebotomist attends your location

• Blood sample taken at home or hotel

• Sample securely transported to the laboratory

Your results explained

Low level

• Olanzapine below expected therapeutic range

• May be associated with reduced treatment response

Typical UK reference examples (vary by lab):

• <20 ng/mL

Therapeutic level

• Olanzapine within expected range

• Suggests appropriate drug exposure

Typical UK reference examples:

• 20–80 ng/mL

High level

• Olanzapine above expected range

• Increased risk of side effects such as sedation or metabolic effects

Typical UK reference examples:

• >80 ng/mL

Interpretation should consider dose timing, symptoms, and clinical context.