| Etiology | Appearance & predominant WBC | Total WBC | (per µl) | RBC (per µl) | Glucose | Comment |
|---|---|---|---|---|---|---|
| Transudates | ||||||
| Congestive heart failure | Clear, straw-colored | <1,000 | M | 0 - 1,000 | PF = S | Usually bilateral |
| Cirrhosis | Clear, straw-colored | <500 | M | <1,000 | PF = S | Incidence of 5% with ascites |
| Exudates | ||||||
| Parapneumonic (uncomplicated) |
Turid | 5,000 -25,000 | P | <5,000 | PF = S | Resolves with antibiotics only |
| Empyema | Turid to purulent | 25,000 -100,000 | P | <5,000 | 0-60 mg/dl | Requires drainage plus antibiotics |
| Pulmonary embolism | Straw-colored to bloody | 5,000 -15,000 | P | 1,000 -100,000 | PF = S | Small to moderate effusion with alveolar infiltrate & volume loss |
| Malignancy | Turid to bloody | <10,000 | M | 1,000 to >100,000 | PF = S or <60 mg/dl |
Cytology & pleural biopsy enable diagnosis in 80% |
| Tuberculosis | Straw-colored to serosanguinous | 1,000-5,000 | L | <5,000 | PF = S or <60 mg/dl |
Positive TST, AFB smear and culture on pleural fluid or biopsy |
| Rheumatoid | Turid, green to yellow | 1,000 - 5,000 | M | <1,000 | Very low (10-20 mg/dl) |
High rheumatoid titer (> 640) Cholesterol crystals |
| Chylothorax | Milky | 1,000 - 7,500 | L | <1,000 | PF = S | Triglycerides > 110/dl, chylomicrons present, usually large |
| Pancreatitis | Turid | 5,000 - 20,000 | P | 1,000 -100,000 | PF = S | Elevated amylase (PF/S > 2) If glucose < 30 mg/dl consider esophageal rupture |
AFB=acid fast bacilli, L=lymphocyte, M=mononuclear, P=polymorphonuclear, PF=pleural fluid, S=serum, TST=tuberculin skin test. RBC = red blood count; WBC = white blood count. Exudative fluid must have one of the following (transudates have none): PF/S protein >.5 or absolute value >3 grams; PF/S LDH >.6 or absolute value >.45 upper normal serum limit; specific gravity >1.018. |
||||||