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Questions and Answers
What should be done to a whole blood ammonia specimen to prevent ammonia level increase before testing?
What should be done to a whole blood ammonia specimen to prevent ammonia level increase before testing?
- Place in an ice slurry (correct)
- Store at room temperature
- Send to the lab immediately
- Keep in a dark location
How quickly should a serum or plasma specimen be centrifuged after collection to avoid altered analyte levels?
How quickly should a serum or plasma specimen be centrifuged after collection to avoid altered analyte levels?
- Within 12 hours
- Within 2 hours (correct)
- Within 6 hours
- Within 30 minutes
What is the maximum time EDTA whole blood tubes can be stored at room temperature without affecting test results?
What is the maximum time EDTA whole blood tubes can be stored at room temperature without affecting test results?
- 72 hours
- 24 hours (correct)
- 12 hours
- 48 hours
What happens to glucose levels in uncentrifuged blood if left standing at room temperature?
What happens to glucose levels in uncentrifuged blood if left standing at room temperature?
For how long can serum and plasma specimens safely remain at room temperature before test results could be adversely affected?
For how long can serum and plasma specimens safely remain at room temperature before test results could be adversely affected?
What should be done with plasma or serum specimens if testing is not completed within 8 hours?
What should be done with plasma or serum specimens if testing is not completed within 8 hours?
What is crucial when thawing frozen specimens before testing?
What is crucial when thawing frozen specimens before testing?
Which of the following test results can be negatively affected by light exposure?
Which of the following test results can be negatively affected by light exposure?
What could happen if a serum specimen is held for more than two hours before centrifugation?
What could happen if a serum specimen is held for more than two hours before centrifugation?
Why is it essential to remove serum from red blood cells after centrifugation?
Why is it essential to remove serum from red blood cells after centrifugation?
What is a key issue with using a pneumatic tube system for laboratory specimens?
What is a key issue with using a pneumatic tube system for laboratory specimens?
Which test is affected by pneumatic tube system transport?
Which test is affected by pneumatic tube system transport?
What is the recommended time for a specimen to clot before centrifugation?
What is the recommended time for a specimen to clot before centrifugation?
What can improper balance of the centrifuge result in?
What can improper balance of the centrifuge result in?
How long should a specimen be transported using a pneumatic tube system?
How long should a specimen be transported using a pneumatic tube system?
What type of pouch is required for urine specimens sent via pneumatic tube?
What type of pouch is required for urine specimens sent via pneumatic tube?
What should you ensure about the carrier used for transporting specimens?
What should you ensure about the carrier used for transporting specimens?
What happens if centrifugation speed is increased too much?
What happens if centrifugation speed is increased too much?
What is the effect of incomplete clotting in serum specimens?
What is the effect of incomplete clotting in serum specimens?
Which of the following tests is NOT affected by pneumatic tube transport?
Which of the following tests is NOT affected by pneumatic tube transport?
What should be checked before a specimen is sent through a pneumatic tube system?
What should be checked before a specimen is sent through a pneumatic tube system?
What happens to glucose levels if there is a delay in centrifugation?
What happens to glucose levels if there is a delay in centrifugation?
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Study Notes
Blood Ammonia and Specimen Handling
- Blood ammonia levels rapidly increase at room temperature due to amino acid breakdown; therefore, a specimen must be placed in ice slurry and transported quickly to the lab.
- Whole blood samples should be separated from cells and tested promptly to avoid altered analyte levels or hemolysis.
- Serum or plasma specimens should be centrifuged within two hours of collection to prevent changes in serum constituents.
Impact of Storage Conditions
- Prolonged contact with cells can falsely alter analyte levels (e.g., increased potassium and decreased glucose).
- Specimens stored at room temperature (20-25°C) can adversely affect test results; serum/plasma should be refrigerated at 2-8°C if testing is delayed, especially beyond eight hours.
- Freezing specimens should be limited to once to prevent analyte deterioration, particularly for tests affected by repeated freeze-thaw cycles.
Light Sensitivity of Specimens
- Light-sensitive tests include Vitamin B12, bilirubin, beta carotene, and folate; these should be collected in amber tubes or wrapped in aluminum foil.
- Tests like Hemoglobin, Hematocrit, and aPTT are unaffected by light exposure.
Effects of Time on Analytes
- Glucose levels decrease by 5% to 7% per hour in uncentrifuged blood at room temperature; timely separation is essential.
- Different analytes may be subject to cellular consumption or release into the serum, skewing results if centrifugation is delayed beyond two hours.
Pneumatic Tube System Transport Protocol
- Transport protocols for laboratory specimens via pneumatic tube system must ensure specimen integrity and safety.
- Tests negatively impacted by pneumatic tube transport include potassium and lactate dehydrogenase, while others like albumin and creatinine are not affected.
Specimen Collection and Clotting
- Non-additive specimens should clot for at least 30 minutes before centrifugation to avoid fibrin residue that can affect testing.
- Improper centrifugation, either due to speed or incomplete clotting, can lead to hemolysis or residual gel particles, interfering with test accuracy.
General Recommendations
- Compliance with standard specimen handling procedures prevents issues such as contamination, hemolysis, and inaccurate test results.
- Proper specimen storage and timely processing are critical to maintaining the integrity of lab results and ensuring patient safety.
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