If lavender EDTA is drawn before SST tube, calcium values would test lower than accurate. Which option best represents this statement?

If lavender EDTA is drawn before SST tube, calcium values would test lower than accurate. Which option best represents this statement?

• A. False
• B. True
• C. Calcium values would test higher than accurate
• D. Calcium values would be unaffected

Answer: (D)

Calcium testing is sensitive to contamination by calcium-chelating additives. Lavender tubes contain EDTA, which binds calcium. If the lavender EDTA tube is drawn before the SST, trace EDTA can contaminate the SST sample, chelating calcium and lowering the measured value. So the statement is true—calcium values would appear lower than accurate. The other options don’t fit because EDTA contamination cannot cause calcium to rise or remain unchanged; the draw order exists to prevent this carryover.

Calcium testing is sensitive to contamination by calcium-chelating additives. Lavender tubes contain EDTA, which binds calcium. If the lavender EDTA tube is drawn before the SST, trace EDTA can contaminate the SST sample, chelating calcium and lowering the measured value. So the statement is true—calcium values would appear lower than accurate. The other options don’t fit because EDTA contamination cannot cause calcium to rise or remain unchanged; the draw order exists to prevent this carryover.