1st order laboratory parameters – obligatory laboratory tests.
- Small blood count*
- Differential blood count* – to assess leukocyte (white blood cell) composition [neutrophil granulocytes: > 4,090/µl → indicating bacterial infection].
- Inflammatory parameters – CRP (C-reactive protein) or PCT (procalcitonin) if sepsis is suspected or ESR (erythrocyte sedimentation rate) [PCT ≥ 1.71 ng/ml → indication of bacterial infection]Note: In elderly patients, procalcitonin is suitable to map the prognosis and severity of pneumonia (pneumonia).
- 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).
- Electrolytes – chloride, sodium, potassium.
- Fasting glucose (fasting blood sugar)
Laboratory parameters 2nd order – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification.
- Infectiology depending on the suspected diagnosis.
- Renal parameters – urea, uric acid and creatinine.
- Liver parameters – alanine aminotransferase (ALT, GPT), aspartate aminotransferase (AST, GOT), glutamate dehydrogenase (GLDH) and gamma-glutamyl transferase (γ-GT, gamma-GT; GGT); bilirubin; alkaline phosphatase.
- LDH
- Creatine kinase (CK)
- D-dimer (end product of proteolysis of fibrin) – Indications: in suspected pulmonary embolismNote: The specificity (probability that actually healthy people who do not have the disease in question are also detected as healthy in the test) of the D-dimer test in suspected pulmonary embolism decreases with age. Therefore, as an alternative to the fixed D-dimer threshold of 500 ng/mL, an age-adjusted cut-off value should be used.
- (without shock) if the risk score is low (see also under “Physical examination” Wells score to determine the clinical probability of pulmonary embolism)Note: If the score is high (Wells score of at least 2 points in the simplified version), immediate CTPA (computed tomography of the pulmonary arteries)/V/P scintigraphy (ventilation/perfusion scintigraphy).
- Negative predictive value 99.3%, thus suitable for screening! If positive: CTPA (computed tomography of the pulmonary arteries), V/P scintigraphy (ventilation/perfusion scintigraphy).
- Highly sensitive cardiac troponin T (hs-cTnT) or troponin I (hs-cTnI) – for suspected myocardial infarction (heart attack).
