Pleural Effusion-Transudate

Etiology

Cardiovascular Disease

Congestive Heart Failure (CHF) (see Congestive Heart Failure)
- Epidemiology
  - XXXX
Constrictive Pericarditis (see Constrictive Pericarditis)
Central Venous Obstruction
- Superior Vena Cava (SVC) Syndrome (see Superior Vena Cava Syndrome)
- Hemiazygos Vein Obstruction
- Brachiocephalic Vein Obstruction
Fontan Procedure (see Fontan Procedure)

Pulmonary Disease

Atelectasis (see Atelectasis)
- Epidemiology
  - XXXXXX
Hantavirus (see Hantavirus)
- Clinical
  - Pleural Fluid is Transudative Early in the Course (Probably Due to Cardiac Dysfunction), Then Later Becomes Exudative
Pleural Amyloidosis (see Amyloidosis)
- Epidemiology
  - Although These Have Been Reported to Be Transudates, Most of These Patients Have Cardiac Amyloidosis and Associated Congestive Heart Failure (CHF)
Pulmonary Veno-Occlusive Disease (see Pulmonary Veno-Occlusive Disease)
Sarcoidosis (see Sarcoidosis)
- Epidemiology
  - Sarcoidosis Rarely Presents with a Transudative Pleural Effusion

Renal Disease

Acute Glomerulonephritis (see Acute Glomerulonephritis)
Nephrotic Syndrome (see Nephrotic Syndrome)
Peritoneal Dialysis (see Peritoneal Dialysis)
Urinothorax (See Pleural Effusion-Urinothorax)

Other Disease

Acute Pulmonary Embolism (PE) (see Acute Pulmonary Embolism)
- Epidemiology
  - Approximately 20% of Acute Pulmonary Embolism-Associated Pleural Effusions are Transudative
Hematopoietic Stem Cell Transplant (SCT, Bone Marrow Transplant) (see Hematopoietic Stem Cell Transplant)
- Epidemiology
  - Most Reported Cases of Transudative Effusions Occurred in Patients with Severe Acute or Chronic Graft vs Host Disease (GVHD) (see Graft vs Host Disease)
Hepatic Hydrothorax (see Hepatic Hydrothorax)
- Epidemiology
  - Hepatic Hydrothorax is Common in Cirrhosis
Hypothyroidism (see Hypothyroidism)
- Epidemiology
  - XXXXX
Inadvertent Central Venous Catheter (CVC) Placement Into Pleural Space (see Central Venous Catheter)
- Pleural Fluid Will Have the Characteristics of the Infusate, So it May Appear to Be Transudative, Exudative, or Chylous
Inadvertent Nasogastric (NG) Tube Placement Into Pleural Space (see Nasogastric/Orogastric Tube)
- Pleural Fluid Will Have the Characteristics of the Infusate, So it May Appear to Be Transudative, Exudative, or Chylous
Meig’s Syndrome (see Meig’s Syndrome)
- Epidemiology
  - Original Description of Pleural Effusion in the Setting of Meig’s Syndrome was Transudative
    - However, Subsequent Clinical Reports Note that These Effusions are Typically Exudative
Pregnancy (see Pregnancy)
- Small Amounts of Ultrasound-Detected Pleural Effusion are a Normal Finding in Pregnancy (Unclear Whether These are Transudative or Exudative)
Severe Hypoalbuminemia (see Hypoalbuminemia)
Subarachnoid-Pleural Fistula

Diagnosis-Pleural Fluid Criteria (see Pleural Effusion-General)

General Comments

LDH Ratio and Total Protein Ratio are Necessary from Light’s Criteria
- The pleural LDH <66% criterion does not add more in discriminative value
Cut-Off Values for LDH and Total Protein Ratios: since there is not a discrete cut-off between values of LDH and total protein, the specified cut-off values give high sensitivity but lower specificity (ie: you will detect all true exudates, but you may misclassify some transudates as exudates, as in diuresed congestive heart failure cases)

Transudate (see Pleural Effusion-Transudate)

LDH Ratio <0.6
Total Protein Ratio <0.5
Pleural LDH <66% of Upper Limit of Normal Range for Serum LDH
Pleural Cholesterol <55-60 mg/L
Pleural/Serum Cholesterol Ratio: normal
Serum-Pleural Albumin Gradient (SPAG) >1.2 g/dL
- If fluid clinically appears to be a transudate and SPAG >1.2, but Light’s criteria suggest exudate, fluid can be assumed to be a transudate (albumin is lower MW than other proteins and crosses capillary walls more easily)

Exudate (see Pleural Effusion-Exudate)

General Comments: pleural effusion is considered exudative if it meets any one of the following criteria, although LDH ratio and total protein ratio are the best criteria
LDH Ratio >0.6
Total Protein Ratio >0.5
Pleural LDH >66% of Upper Limit of Normal Range for Serum LDH
Pleural Cholesterol >55-60 mg/dL
Pleural/Serum Cholesterol Ratio: elevated
Serum-Pleural Albumin Gradient (SPAG) <1.2 g/dl
- If fluid clinically appears to be a transudate and SPAG >1.2, but Light’s criteria suggest exudate, fluid can be assumed to be a transudate (albumin is lower molecular weight than other proteins and crosses capillary walls more easily)

References

Unexplained effusions: association with allogeneic bone marrow transplantation and acute or chronic graft-versus-host disease. Bone Marrow Transplant. 1996 Feb;17(2):207-11 [MEDLINE]