The statement 'lavender EDTA tubes binding calcium could cause falsely low calcium values if drawn before an SST tube' is:

The statement 'lavender EDTA tubes binding calcium could cause falsely low calcium values if drawn before an SST tube' is:

• A. False
• B. True
• C. Cannot be determined
• D. Sometimes true

Answer: (B)

Calcium in the blood sample can be falsely lowered if a tube containing a calcium-binding anticoagulant is drawn before a serum tube. Lavender EDTA tubes contain EDTA, which chelates calcium. If the EDTA tube is collected first, trace EDTA can contaminate the subsequent serum tube and bind calcium in that sample, giving a falsely low calcium result. This is why proper order of draw places serum tubes before EDTA tubes—to prevent cross-contamination and inaccurate calcium measurements.

Calcium in the blood sample can be falsely lowered if a tube containing a calcium-binding anticoagulant is drawn before a serum tube. Lavender EDTA tubes contain EDTA, which chelates calcium. If the EDTA tube is collected first, trace EDTA can contaminate the subsequent serum tube and bind calcium in that sample, giving a falsely low calcium result. This is why proper order of draw places serum tubes before EDTA tubes—to prevent cross-contamination and inaccurate calcium measurements.