1st-order laboratory parameters-obligatory laboratory tests.
- Small blood count [platelets (thrombocytes) ↓]
- Inflammatory parameter – PCT (procalcitonin)/Guidelines recommend determination of PCT [procalcitonin increases within a few hours (2-3 h) and reaches its maximum after only 24 hours; PCT concentrations:
- <0.5 ng/mL exclude severe sepsis or septic shock with high probability
- > 2 ng/mL make severe sepsis or septic shock highly probable]
- Urine status (rapid test for: pH, leukocytes, nitrite, protein, glucose, ketone, urobilinogen, bilirubin, blood), sediment, if necessary urine culture (pathogen detection and resistogram, that is, testing of appropriate antibiotics for sensitivity / resistance).
- Electrolytes – calcium, chloride, potassium, magnesium, sodium, phosphate.
- Fasting glucose (fasting blood glucose), if necessary oral glucose tolerance test (oGTT).
- Blood gas analysis (BGA) including for the determination of: PaO2/FiO2 (mmHg) [arterial oxygen partial pressure in mmHg/inspiratory O2 concentration; indicates the percentage of oxygen].
- Thyroid parameters – TSH
- Pancreatic parameters – amylase, elastase (in serum and stool), 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.
- Coagulation parameters – PTT, Quick, antithrombin activity (AT III).
- Lactate – if lactic acidosis is suspected (form of metabolic acidosis in which a drop in blood pH is due to accumulation of acid lactate) [plasma lactate level ≥ 2.0 mmol/l and a pH of < 7.35]
- Microbiological smears and/or cultures (aerobic and anaerobic blood cultures; 2 times 2 or better 3 times 2 blood cultures); if necessary also from venous accesses or from drains.
- Note: In urosepsis, for example, blood cultures are positive in just under 30% of cases.
- Blood gas analysis (BGA), among other things, to determine: PaO2/FiO2 (mmHg) [arterial oxygen partial pressure in mmHg/inspiratory O2 concentration; indicates the percentage of oxygen].
Laboratory parameters of the 2nd order – depending on the results of the history, physical examination and the obligatory laboratory parameters – for differential diagnostic clarification
- Interleukin-6 (IL-6), tumor necrosis factor (synonyms: TNF α, cachectin, lymphotoxin), or lipopolysaccharide-binding protein-laboratory parameters that may indicate sepsis at an early stage.
- Toxicological tests – if intoxications are suspected.
Note: Laboratory parameters marked in bold that are taken into account in the SOFA score (see below sepsis/classification).
In up to 30% of illnesses, no confirmed pathogen detection can be made in sepsis.
