Razan Suliman: When do we use sodium citrate instead of EDTA for a CBC?
Razan Suliman, Medical Laboratory Specialists at Qater medical lab, shared a post on LinkedIn:
”A patient’s platelet count comes back extremely low.
The clinician is concerned. The patient has no signs of bleeding. The result doesn’t match the clinical picture.
So, what’s going on?
Could the platelet count be wrong?
Before diagnosing thrombocytopenia, laboratory professionals should ask an important question:
Is EDTA the problem?
Although EDTA is the anticoagulant of choice for routine CBC testing, there are situations where it can cause platelet clumping in vitro. As a result, the analyzer may report a falsely low platelet count, a phenomenon known as EDTA-dependent pseudothrombocytopenia.
In such cases, the solution may be surprisingly simple:
Collect a new sample in a sodium citrate tube.Sodium citrate can prevent the platelet clumping seen with EDTA, helping us obtain a more accurate platelet count and avoid unnecessary investigations or treatments.
When do we use sodium citrate instead of EDTA for a CBC?
- When platelet clumping is observed on the blood film.
- When the platelet count is unexpectedly low and does not correlate with the patient’s condition.
- When EDTA-dependent pseudothrombocytopenia is suspected.
Remember: Not every low platelet count is a true thrombocytopenia.
Question for laboratory professionals: Have you ever encountered EDTA-induced platelet clumping in your practice? How was it identified and resolved?”

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