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Protein, Total, Body Fluid
Test Code12527
CPT Codes
84157<br>Limited Access Code
Preferred Specimen
1 mL body fluid from the following sources:
-Peritoneal fluid (peritoneal, abdominal, ascites, paracentesis)
-Pleural fluid (pleural, chest, thoracentesis)
-Drain fluid (drainage, JP drain)
-Pericardial
-Peritoneal fluid (peritoneal, abdominal, ascites, paracentesis)
-Pleural fluid (pleural, chest, thoracentesis)
-Drain fluid (drainage, JP drain)
-Pericardial
Minimum Volume
0.5 mL
Instructions
1. Centrifuge to remove any cellular material and transfer into a plastic vial
2. Indicate the specimen source and source location on label
3. Date and time of collection are required
2. Indicate the specimen source and source location on label
3. Date and time of collection are required
Transport Container
Sterile plastic leak-proof container
Transport Temperature
Refrigerated (cold packs)
Specimen Stability
Room temperature: 24 hours
Refrigerated: 7 days
Frozen: 30 days
Refrigerated: 7 days
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Grossly lipemic • Grossly icteric • Anticoagulant or additive • Breast milk • Nasal secretions • Gastric secretions • Bronchoalveolar lavage (BAL) or bronchial washings • Colostomy/ostomy • Feces • Cerebrospinal fluid • Saliva • Sputum • Urine • Vitreous fluid
Methodology
Colorimetric
FDA Status
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.
Setup Schedule
Set up: Daily; Report available: 1-2 days
Clinical Significance
Pleural fluid
Pleural fluid is normally present within the pleural cavity surrounding the lungs, serving as a lubricant between the lungs and inner chest wall. Pleural effusion develops when the pleural cavity experiences an overproduction of fluid due to increased capillary hydrostatic and osmotic pressure that exceeds the ability of the lymphatic or venous system to return the fluid to circulation. Laboratory-based criteria are often used to classify pleural effusions as either exudative or transudative. Exudative effusions form due to infection or inflammation of the capillary membranes allowing excess fluid into the pleural cavity. Patients with these conditions benefit from further investigation and treatment of the local cause of inflammation. Transudative effusions form due to systemic conditions such as volume overload, end stage renal disease, and heart failure that can lead to excess fluid accumulation in the pleural cavity. Patients with transudative effusions benefit from treatment of the underlying condition.(1)
Dr. Richard Light derived criteria in the 1970s that are still used today for patients with pleural effusions.(2)
The criteria include the measurement of total protein and lactate dehydrogenase (LDH) in pleural fluid and serum. Exudates are defined as meeting 1 of the following criteria:
1. Pleural fluid to serum protein ratio above 0.5
2. Pleural fluid LDH above two-thirds the upper limit of normal serum LDH
3. Pleural fluid to serum LDH ratio above 0.6
Dr. Light's criteria were designed to be sensitive for detecting exudates at the expense of specificity.(3) Heart failure and recent diuretic use contribute to most misclassifications by Dr. Light's criteria (transudates falsely categorized as exudates). Serum-to-fluid protein gradient (serum protein minus fluid protein) may be calculated in these cases and when more than 3.1 g/dL suggests the patient has a transudative effusion.
Peritoneal fluid
The pathologic accumulation of fluid within the peritoneal cavity is commonly referred to as ascites. The most common cause of ascites is liver cirrhosis. Differentiating cardiac from cirrhotic ascites is a common clinical conundrum as they are common conditions presenting with elevated serum ascites albumin gradient (SAAG).(4) Heart failure leads to the development of high gradient ascites due to hepatic sinusoidal hypertension. Since the sinusoids are normal and have not been damaged from collagen deposition associated with cirrhosis, protein tends to "leak" more readily into ascites and is associated with higher total protein concentrations.
Clinical Reference
1. Block DR, Florkowski CM: Body fluids. In: Rafai N, Horvath AR, Wittwer CT. eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier;2018: chap43
2. Light RW: The Light criteria: the beginning and why they are useful 40 years later. Clin Chest Med. 2013 Mar;34 (1):21-26
3. Porcel JM: Identifying transudates misclassified by Light's criteria. Curr Opin Pulm Med. 2013;19:362-367
4. Block DR, Genzen JR: Diagnostic body fluid testing. In: Clarke W, ed. Contemporary Practice in Clinical Chemistry. 3rd ed. AACC Press; 2016:773-775
Pleural fluid is normally present within the pleural cavity surrounding the lungs, serving as a lubricant between the lungs and inner chest wall. Pleural effusion develops when the pleural cavity experiences an overproduction of fluid due to increased capillary hydrostatic and osmotic pressure that exceeds the ability of the lymphatic or venous system to return the fluid to circulation. Laboratory-based criteria are often used to classify pleural effusions as either exudative or transudative. Exudative effusions form due to infection or inflammation of the capillary membranes allowing excess fluid into the pleural cavity. Patients with these conditions benefit from further investigation and treatment of the local cause of inflammation. Transudative effusions form due to systemic conditions such as volume overload, end stage renal disease, and heart failure that can lead to excess fluid accumulation in the pleural cavity. Patients with transudative effusions benefit from treatment of the underlying condition.(1)
Dr. Richard Light derived criteria in the 1970s that are still used today for patients with pleural effusions.(2)
The criteria include the measurement of total protein and lactate dehydrogenase (LDH) in pleural fluid and serum. Exudates are defined as meeting 1 of the following criteria:
1. Pleural fluid to serum protein ratio above 0.5
2. Pleural fluid LDH above two-thirds the upper limit of normal serum LDH
3. Pleural fluid to serum LDH ratio above 0.6
Dr. Light's criteria were designed to be sensitive for detecting exudates at the expense of specificity.(3) Heart failure and recent diuretic use contribute to most misclassifications by Dr. Light's criteria (transudates falsely categorized as exudates). Serum-to-fluid protein gradient (serum protein minus fluid protein) may be calculated in these cases and when more than 3.1 g/dL suggests the patient has a transudative effusion.
Peritoneal fluid
The pathologic accumulation of fluid within the peritoneal cavity is commonly referred to as ascites. The most common cause of ascites is liver cirrhosis. Differentiating cardiac from cirrhotic ascites is a common clinical conundrum as they are common conditions presenting with elevated serum ascites albumin gradient (SAAG).(4) Heart failure leads to the development of high gradient ascites due to hepatic sinusoidal hypertension. Since the sinusoids are normal and have not been damaged from collagen deposition associated with cirrhosis, protein tends to "leak" more readily into ascites and is associated with higher total protein concentrations.
Clinical Reference
1. Block DR, Florkowski CM: Body fluids. In: Rafai N, Horvath AR, Wittwer CT. eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier;2018: chap43
2. Light RW: The Light criteria: the beginning and why they are useful 40 years later. Clin Chest Med. 2013 Mar;34 (1):21-26
3. Porcel JM: Identifying transudates misclassified by Light's criteria. Curr Opin Pulm Med. 2013;19:362-367
4. Block DR, Genzen JR: Diagnostic body fluid testing. In: Clarke W, ed. Contemporary Practice in Clinical Chemistry. 3rd ed. AACC Press; 2016:773-775
