Selected blood values: CRP value

The CRP value has gained great importance for the diagnosis and monitoring of inflammatory reactions. CRP stands for C-reactive protein. This name comes from the property that this endogenous protein binds to the so-called C-polysaccharide of a certain bacterium.

It then triggers the activation of a series of immune processes that lead to the fight against invading bacteria. CRP is activated by many different bacteria, fungi and components of cancer cells. However, viruses do not usually lead to activation.

This is one of the reasons why CRP is particularly interesting for doctors. The analysis of the CRP level in the blood is suitable for differentiating between a bacterial and a viral cause of an infection. This can be used to decide on the use of antibiotics, for example.

While bacterial infections, depending on the pathogen and severity, sometimes lead to massively increased CRP values, viral infections usually cause no or only slight increases in CRP. A particular advantage of the CRP value compared to other inflammation values is that it increases extremely quickly and sharply in the case of a bacterial infection. Due to this property, the CRP is counted among the so-called acute phase proteins.

A long-term and moderately increased CRP can indicate an underlying disease, for example a tumour, or an autoimmune disease. However, it is important to note that an increase in CRP does not always specifically indicate an inflammation or a malignant disease. For example, it can also be caused by injuries sustained (even during an operation).

Selected blood values: thyroid diagnostics

The following three values are important in standard thyroid diagnostics: the thyroid hormones triiodothyronine (T3 for short) and thyroxine (T4 for short), as well as the control hormone thyroid stimulating hormone (TSH). T3 and T4 are bound to far more than 99 percent of proteins in the blood. If the small proportion of free, i.e. unbound T3 and T4 is determined, the values are referred to as fT3 and fT4.

The determination of these unbound hormones provides better information about the function of the thyroid gland than the corresponding total values. While T3 and T4 are produced in the thyroid gland, TSH is produced in a special area of the brain, the pituitary gland. Its function in the body is to control the release of thyroid hormones.

In a healthy person, the following control loop exists: When T3 and T4 are reduced, more TSH is released. TSH increases the release of T3 and T4 from the thyroid gland: T3 and T4 increase. This in turn reduces the release of TSH.

This mechanism ensures that the body always has exactly the amount of hormones it needs at any given time. However, due to various causes, the concentration of thyroid hormones in the blood may still be too high (hyperthyroidism) or too low (hypothyroidism). By determining (f)T3, (f)T4 and TSH, the doctor can then determine the extent of the disorder and often possible causes.

In practice, sometimes only the TSH value is determined, as in the majority of cases it can already give a good indication of a disturbed thyroid function. Common causes of hyper- and hypothreosis are two autoimmune diseases: for an underfunction the autoimmune hypothyroidism (Hashimoto’s thyroiditis), for an overfunction the autoimmune hyperthyroidism (Graves’ disease). In these diseases there are often antibodies against the body’s own structures which can be detected in the blood.

In Hashimoto’s thyroiditis, these are antibodies against the enzyme thyroid peroxidase (TPO-AK) and the protein thyroglobulin. In Graves’ disease, TPO-AK and so-called TSH receptor antibodies (TRAK) are also detected. Other special thyroid values are used for diagnosis and control of malignant tumours of the thyroid gland and are therefore called tumour markers. For the thyroid gland these are, depending on the type of tumour, Caltitonin and Thyroglobulin.