Podcast
Questions and Answers
What is the primary reason for the rapid separation of blood after centrifugation?
What is the primary reason for the rapid separation of blood after centrifugation?
- To prevent the shift in electrolytes (correct)
- To enhance the color reactions in serum
- To increase the total protein synthesis
- To facilitate better hemolysis of cells
Which analytes can demonstrate falsely elevated levels due to delays in blood separation?
Which analytes can demonstrate falsely elevated levels due to delays in blood separation?
- Glucose and total bilirubin
- Sodium and potassium (correct)
- Enzymes like LD and AST
- Albumin and cholesterol
Which substance is least stable in serum if not removed from the clot within 30 minutes?
Which substance is least stable in serum if not removed from the clot within 30 minutes?
- Urea
- Glucose
- Total protein
- Potassium (correct)
What interference does bilirubin levels greater than 25 mg/L have on laboratory tests?
What interference does bilirubin levels greater than 25 mg/L have on laboratory tests?
Which of the following may increase if hemolysis occurs during blood sample processing?
Which of the following may increase if hemolysis occurs during blood sample processing?
What is the blood clotting time for a serum tube with a clot activator and gel separator?
What is the blood clotting time for a serum tube with a clot activator and gel separator?
How many times should you invert a red top serum tube that contains a clot activator?
How many times should you invert a red top serum tube that contains a clot activator?
Which anticoagulant is known as an ideal universal anticoagulant?
Which anticoagulant is known as an ideal universal anticoagulant?
What is the unique characteristic of the gel separator found in SSTs?
What is the unique characteristic of the gel separator found in SSTs?
What samples must NOT be collected in SST tubes due to possible interference with drug monitoring?
What samples must NOT be collected in SST tubes due to possible interference with drug monitoring?
Which heparin is preferred for microcollection tubes?
Which heparin is preferred for microcollection tubes?
Which of the following tests should lithium heparin be used for?
Which of the following tests should lithium heparin be used for?
What can re-spinning of gel tubes falsely increase?
What can re-spinning of gel tubes falsely increase?
What is the primary function of EDTA in phlebotomy?
What is the primary function of EDTA in phlebotomy?
How does excess EDTA affect red blood cells?
How does excess EDTA affect red blood cells?
Which anticoagulant is used specifically in Grey Top tubes?
Which anticoagulant is used specifically in Grey Top tubes?
What is the main purpose of Sodium Fluoride in specimen collection?
What is the main purpose of Sodium Fluoride in specimen collection?
How many times should tubes containing anticoagulants be inverted?
How many times should tubes containing anticoagulants be inverted?
What effect does EDTA contamination have on electrolyte levels?
What effect does EDTA contamination have on electrolyte levels?
Which of the following tests is NOT typically associated with EDTA?
Which of the following tests is NOT typically associated with EDTA?
Which anticoagulant interferes with Na+, K+, and most BUN measurements?
Which anticoagulant interferes with Na+, K+, and most BUN measurements?
Which physiological condition is likely to result in increased levels of cortisol and glucose?
Which physiological condition is likely to result in increased levels of cortisol and glucose?
What effect does chronic alcohol ingestion have on plasma glucose levels?
What effect does chronic alcohol ingestion have on plasma glucose levels?
Which of the following statements about serum electrolyte levels is true after recent food intake?
Which of the following statements about serum electrolyte levels is true after recent food intake?
How do diuretics commonly affect plasma levels?
How do diuretics commonly affect plasma levels?
What is the physiological variation in albumin levels related to age?
What is the physiological variation in albumin levels related to age?
What effect does vigorous exercise have on potassium levels in the body?
What effect does vigorous exercise have on potassium levels in the body?
Which fasting duration is most likely to result in elevated serum bilirubin levels?
Which fasting duration is most likely to result in elevated serum bilirubin levels?
What is the primary effect of a high protein diet on plasma levels?
What is the primary effect of a high protein diet on plasma levels?
Which statement is true regarding post absorptive hormonal effects?
Which statement is true regarding post absorptive hormonal effects?
What is the clinical term for fasting 'nil per os'?
What is the clinical term for fasting 'nil per os'?
How does caffeine affect glucose concentration in the blood?
How does caffeine affect glucose concentration in the blood?
Which analytes are typically included in a basic metabolic panel?
Which analytes are typically included in a basic metabolic panel?
What can prolonged fasting for 72 hours do to plasma triglyceride levels in males?
What can prolonged fasting for 72 hours do to plasma triglyceride levels in males?
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Study Notes
Phlebotomy Overview
- Rapid separation of blood after centrifugation is crucial to prevent glycolysis and preserve unstable substances.
- Delays in separation beyond 24 hours can cause increased total bilirubin, electrolytes, urea, albumin, and total protein.
- Key analytes least stable in serum if not separated within 30 minutes: potassium, phosphorus, glucose.
Importance of Rapid Blood Separation
- Prevents electrolyte shifts leading to falsely elevated potassium and falsely decreased sodium levels in serum and plasma.
- Minimizes hemolysis which can falsely inflate enzyme (LD, ACP, ALT, AST) and electrolyte (magnesium, phosphorus, potassium) levels.
- High bilirubin levels (>25 mg/L) can interfere with albumin and cholesterol tests, along with inhibiting lipase enzyme function.
Anticoagulant Tubes
-
Red Top Tubes:
- Silicone coated or clot activator; 60 minutes clotting time; no inversions for glass, 5 inversions for plastic.
-
Serum Separator Tubes (SSTs):
- Gel separator between blood clot and serum; 30 minutes clotting time and 5 tube inversions; unsuitable for therapeutic drug monitoring.
Heparin as Anticoagulant
- Regarded as an ideal universal anticoagulant via its anti-thrombin and anti-thromboplastin actions.
- Used for testing potassium, ammonium, cytogenetic studies, and various other analytes.
- Not suitable for nucleic acid testing due to DNA co-extraction.
EDTA (Ethylenediamine Tetraacetic Acid)
- Chelates calcium; used for CBC, CEA, and lead testing.
- Excess can alter RBC count results. Effective for nucleic acid testing.
Other Anticoagulants
-
Potassium Oxalate:
- Forms insoluble salts with calcium; interferes with multiple measurements, used in Grey Top tubes.
-
Sodium Fluoride:
- Acts as an antiglycolytic agent, preventing glycolysis for up to 48-72 hours; important for ethanol and lactate testing.
Patient Preparation Factors
- Exercise can transiently increase lactate and affect other analytes; prolonged exercise can elevate specific muscle enzymes.
- Fasting affects serum composition; for example, fasting for 48 hours can elevate bilirubin levels.
- Diet impacts metabolic products; high-protein diets raise urea and uric acid levels.
Physiological Variables
- Age, gender, and recent food ingestion affect analyte levels; males generally show higher albumin and uric acid, while females have higher HDL.
Stress and Drug Influence
- Acute stress elevates catecholamines and cortisol, which can increase glucose and lactate levels.
- Drugs can significantly alter plasma concentrations, affecting test results; diuretics lower sodium and potassium levels.
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