Laboratory parameters of 1st order – obligatory laboratory tests.
- Small blood count
- Differential blood count
- Inflammatory parameters – CRP (C-reactive protein) or PCT (procalcitonin).
- Diagnostic puncture of the pleural effusion (obtaining 20-50 ml) and examination (see below) for: Protein content (protein content), pH, cell components (e.g., malignant cells), microbiological pathogen diagnostics, LDH, glucose.
Laboratory parameters 2nd order – depending on the results of the history, physical examination and the obligatory laboratory parameters – for differential diagnostic clarification.
- Urine status (rapid test for: Nitrite, protein, hemoglobin, erythrocytes, leukocytes, urobilinogen) incl. sediment, if necessary urine culture (pathogen detection and resistogram, that is, testing of suitable antibiotics for sensitivity / resistance).
- Thyroid parameters – TSH
- Pancreatic parameters – amylase, elastase and lipase.
- Liver parameters – alanine aminotransferase (ALT, GPT), aspartate aminotransferase (AST, GOT), glutamate dehydrogenase (GLDH) and gamma-glutamyl transferase (gamma-GT, GGT), alkaline phosphatase, bilirubin.
- Renal parameters – urea, creatinine, cystatin C or creatinine clearance, if necessary.
- Highly sensitive cardiac troponin T (hs-cTnT) or troponin I (hs-cTnI); creatine kinase (CK, CK-MB), lactate dehydrogenase (LDH) – to exclude a myocardial infarction (heart attack).
- NT-proBNP (N-terminal pro brain natriuretic peptide) – to diagnose heart failure [diagnosis of an exudate + NT-proBNP ↑ = heart failure very likely].
- Serological examination – if bacterial, viral or parasitic infections are suspected.
- Tumor markers – on suspicion of malignant (malignant) neoplasms and as a progress control [see for the corresponding suspected diagnosis / disease under laboratory diagnostics].
- ANA (antinuclear antibodies), ENA antibodies – for suspected collagenosis.
Differential diagnosis: transudate and exudate
The following parameters contribute to the differentiation between transsudate and exudate:
| Transudate | Exudate | |
| Total white in g/l | < 30 | > 30 |
| Specific weight | < 1.016 | > 1.016 |
| Pleural TP: serum TP (total protein quotient; total protein, TP). | < 0,5 | > 0,5 |
| LDH in U/l | < 200 | > 200 |
| Pleural LDL: serum LDL (LDL quotient). | < 0,6 | > 0,6 |
Diseases that may be associated with transudate:
- Heart failure (cardiac insufficiency): decompensated left heart failure.
- Hypalbuminemia (decreased concentration of the plasma protein albumin in blood plasma):
- Exudative enteropathy (protein-losing intestinal disease; enteral protein loss syndrome).
- Liver cirrhosis – connective tissue remodeling of the liver leading to functional impairment.
- Nephrotic syndrome – collective term for symptoms that occur in various diseases of the glomerulus (renal corpuscles); symptoms are proteinuria (increased excretion of protein in the urine) with a protein lossof more than 1 g/m²/body surface per day; hypoproteinemia, peripheral edema due to hypalbuminemia of < 2.5 g/dl in serum, hyperlipoproteinemia (lipid metabolism disorder).
- Malnutrition
- Renal insufficiency (kidney weakness)
Diseases that may be associated with exudate:
- Bacterial infections of the thoracic or abdominal organs (e.g., tuberculosis): leukocytes ↑, glucose ↓; pathogen detection if necessary.
- Malignant neoplasms (mammary, lung and pleura: often hemorrhagic, if necessary detection of malignant cells).
- Collagenoses (group of connective tissue diseases caused by autoimmune processes) – systemic lupus erythematosus (SLE), polymyositis (PM) or dermatomyositis (DM), Sjögren’s syndrome (Sj), scleroderma (SSc) and Sharp syndrome (“mixed connective tissue disease”, MCTD).
- Pulmonary embolism
- Pneumonia (inflammation of the lungs)
- Condition n. surgery or trauma
For more information, see “Examination of pleural effusion“.