Laboratory parameters of the 1st order – obligatory laboratory tests.
- Inflammatory diagnostics – in case of fever above 38.3 °C, severe symptoms, increase of symptoms during the course of the disease, threatening complications
- CRP (C-reactive protein); more appropriate is the determination of procalcitonin, which allows some differentiation of bacterial and viral infections.
- Leukocytes (white blood cells).
Note: Elevations in CRP correlate with radiographic findings and clinical severity of infection (in this case, sinusitis).
Laboratory parameters 2nd order – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification.
- Microscopy, culture procedures, germ identification if necessary and resistance testing (in case of resistance to therapy)Indications: In acute rhinosinusitis (ARS) dispensable and only to be considered if a given therapy within 48-72 h leads to no improvement or in underlying diseases associated with immune deficiency (consensus decision of the S2k guideline).
- Nasal biopsy – collection of tissue samples from the nasal mucosa (indication: suspected malignancies, granulomatoses and invasive fungal diseases).
- Allergen diagnostics (to detect an allergic disposition/disposition).
- Prick test (skin test; method of choice): in this case, the allergens in question are applied in droplet form to the forearms. A thin needle is used to slightly nick the skin at these sites, allowing the test solution to enter the skin. This is only slightly painful – only the top layer of skin is scratched. If erythema (reddening of the skin over a large area) or wheals appear after about 15 to 30 minutes, the test is positive. However, a positive test result only indicates that sensitization to the substance has occurred. However, the substance does not have to be the triggering allergen. Therefore, other investigations such as the provocation test usually follow to confirm the result.
- Antibody detection (useful supplement to the prick test if skin test is not possible (eczema, hypersensitive skin with positive reaction to the solvent, lack of reaction of the skin to histamine, lack of test substance), or the result is not clearly readable (eg, dermographism)):
- Ig-E detection (= total IgE or allergen-specific IgE in serum) – if allergy of the immediate type (type I) is suspected; especially if a skin test (see above) is difficult to perform or would put the patient at risk.
- Precipitating IgG antibodies (allergy type III).
