Also in the diagnosis of sarcoidosis, it is important to distinguish between the acute and the chronic forms of sarcoidosis. In any case, a comprehensive anamnesis interview and a physical examination should be carried out by the attending physician first.
If there is a suspicion here of the presence of a Löfgren syndrome, an X-ray of the lung should be made. On such a bihilar lymphadenopathy is then usually very clearly visible. Also, the classification can be made on the basis of an X-ray image, this is then a good starting point for the preparation of a therapy plan.
Furthermore, a laboratory examination of the blood should be requested. Here, as an expression of an inflammatory reaction of the body, increased inflammatory values result, a so-called "acute phase reaction" with elevated C-reactive protein (CRP value) and increased erythrocyte sedimentation rate.
In 65% of cases, a blood test can be used to measure an increased activity of a certain enzyme, the so-called angiotension-converting enzyme. However, this method has an uncertain specificity, that is, an increase in angiotension converting enzyme is also found in other diseases. Therefore, this parameter is especially suitable for follow-up.
If a chronic form of sarcoidosis is present, an x-ray picture of the lung can be very helpful just as in the acute form; a computerized tomogram can usually detect changes in the connective tissue of the lungs and the precise involvement of the lymph nodes. Finally, further information could be obtained by improving the MRI of the lung.
Furthermore, a biopsy, ie a sample of the body's own tissue should be taken in order to then be able to examine the individual granulomas with their cells in fine tissue. In this way, it is often possible to exclude other diseases that also result in nodule formation. Importantly, knowing that sarcoidosis-type granulomas can also occur in tuberculosis and Crohn's disease, an inflammatory bowel disease.
If one has the assumption that the heart is affected, then one should make an ECG for the detection of possibly existing cardiac arrhythmias.
Depending on the method of diagnosis, there are different criteria. The focus is firstly on the question of acute inflammation and secondly on the question of the localization of sarcoidosis in various organs.
There are also several parameters in the blood, such as calcium, which are also related to the progression and prognosis of the disease. In the case of the X-ray of the lung, the progress of the lung involvement is mainly assessed on the basis of the lymph nodes and the change in the lung tissue.
An examination of the blood and the evaluation of the laboratory values are standard in a diagnosis of sarcoidosis.
In the acute form of the disease, various inflammatory parameters, such as the leukocytes, so the white blood cells, can be checked.
In chronic sarcoidosis, certain antibodies and calcium levels are also checked. If the latter is increased, this may have a negative effect on the function of the kidney and thus the prognosis. Certain receptors are also evaluated in chronic sarcoidosis to control disease progression.
The most well-known means of diagnosing sarcoidosis is the X-ray of the lungs. This has become prominent above all, as this often diagnoses the chronic form of sarcoidosis as a chance finding.
In this imaging, especially the lymph nodes located in the area of the lung root are assessed. If these are enlarged, this may be a typical indication of the presence of the disease. In later stages, they are often less swollen. There is then an infection of the lung tissue, which can be fibrotic, ie scarred, convert and as such is visible in the X-ray.
In a lung reflection, also called bronchoscopy, both a lung lavage and a biopsy of the lymph nodes of the lungs can be performed. The latter is usually done with the help of a fine needle. A small piece of tissue is removed from a lymph node under control with an ultrasound machine.
This can then be examined in the laboratory using a microscope and various tests. Above all, the number and type of existing cells are evaluated, which can give indications of the stage of the disease. In later stages tissue samples of lung tissue can also be biopsied and examined.
In rare cases scintigraphy may also be used to diagnose sarcoidosis. Radioactively labeled gallium particles are introduced into the body via the bloodstream. These then accumulate in tissue areas in which an active inflammation process takes place.
These tissue areas are also referred to as granulomas. The whole can then be measured with the help of the scintigraphy. However, since this method involves risks and is very expensive, it is rarely used today. To check the involvement of various organs, an MRI image of the lungs can be taken instead.
Probably the most important differential diagnosis for sarcoidosis is the tuberculosis disease. It also typically affects the lungs and can have serious consequences if there is no diagnosis.
Other possible alternative diagnoses include various cancers of the lymphatic system, such as Hodgkin's disease or non-Hodgkin's lymphoma.
In addition, abnormal accumulation of foreign particles can lead to similar symptoms. This includes, for example, the fumed silica, which can lead to so-called silicosis after years of inhalation, for example, in mines.
Sarcoidosis can be diagnosed by various methods. This includes first the history, ie the doctor-patient interview, and a physical examination to record the exact symptoms. When examining the blood, various parameters can provide evidence of the disease.
Probably the best known diagnostic method of sarcoidosis is the X-ray of the lung. Furthermore, a bronchoscopy, ie a lung reflection, a pulmonary function test and a CT of the lungs can be helpful. To assess the involvement of organs other than the lungs, an ECG, MRI and PET scan can be used.