Cilastatin-Induced Platelet IgM Antibody, Serum/Plasma — Qualitative
A specialized qualitative test for IgM antibodies that bind platelets in the presence of cilastatin, used when drug-related immune thrombocytopenia is suspected.
["A positive result may support cilastatin-induced immune thrombocytopenia, a rare reaction that can cause a low platelet count."]
Key facts at a glance
- LOINC
- 73449-1
- Short code
- Cilastatin ind plt IgM SerPl Ql FC
- Synonyms
- Cilastatin ind plt IgM SerPl Ql FC
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- flow-cytometry
- CPT
- 84484
- SNOMED
- 302774002
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This blood test checks for IgM antibodies that attach to platelets when the antibiotic component cilastatin is present. It is a specialized test used to investigate a possible immune reaction to cilastatin, which is usually given with imipenem.
Why might I need this test?
The test may be ordered if you developed a low platelet count, bruising, bleeding, or small blood spots on the skin after receiving cilastatin. It helps determine whether the immune system produced an antibody that targets platelets in response to the drug.
How is the test performed?
A blood sample is collected and separated into serum or plasma. A laboratory then evaluates whether the sample contains IgM that binds to platelets in the presence of cilastatin, using appropriate comparison controls.
How do I prepare for the test?
No special preparation is usually required unless the ordering laboratory provides specific instructions. Be sure to tell your clinician about cilastatin or imipenem use, the timing of your symptoms, and any bleeding or unusual bruising. Do not stop prescribed medication without medical advice.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A positive result indicates that the blood contains cilastatin-dependent platelet IgM and may support a diagnosis of cilastatin-induced immune thrombocytopenia. This is a rare drug reaction in which immune antibodies promote platelet destruction, sometimes causing bleeding. A negative result does not completely exclude the condition because testing can be affected by antibody levels, timing, or other factors.
Short name
Cilastatin-dependent platelet IgM antibody
Frequently asked questions
What does a positive result mean?
Does a positive result mean my current platelet problem was definitely caused by cilastatin?
What should I do if I have bleeding or severe bruising after this medication?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy