Protein S-100
Why this test?
This test is used for the diagnosis, prognosis assessment, and treatment monitoring of certain oncological, neurological, inflammatory, and other diseases.
In which cases is it prescribed?
In oncology, it is used for the diagnosis of melanoma and certain other malignant tumors. In neurology, it is used in cases of traumatic brain injury, neonatal asphyxia, neurodegenerative disorders (such as Alzheimer's disease). In cardiology, it is used for heart failure and acute ischemia. In rheumatology, it is used for rheumatoid arthritis, systemic lupus erythematosus, psoriasis, and other autoimmune diseases.
Information about the test
S-100 proteins are small calcium-binding proteins. Currently, about 25 S-100 proteins are known. They perform various functions in the human body, including cell growth and differentiation, transcription, protein phosphorylation, secretion, muscle contraction, and other processes. They regulate the cell cycle and apoptosis and can be involved in oncogenesis. The concentration of S-100 proteins changes in many malignant diseases, which can be used for the diagnosis and prognosis of tumors. The S-100B protein is most diagnostically significant for melanoma. S-100B is a standard immunohistochemical marker routinely used in the pathological diagnosis of melanoma. It is also released by malignant melanocytes into the blood, where it can be measured. Currently, S-100B protein is the most extensively studied biomarker for melanoma. It has been shown that the level of S-100B protein correlates well with the clinical stage of melanoma. An increase in the level of this biomarker indicates melanoma progression, while a decrease in its concentration indicates regression. It has been shown that the informativeness of the S-100B biomarker for evaluating melanoma treatment is higher than that of another melanoma biomarker, lactate dehydrogenase (LDH). Increased S-100B protein levels are also observed in astrocytomas, kidney tumors, certain types of leukemia, as well as in kidney and liver diseases (including metastases of various tumors to the liver) and various inflammatory and infectious diseases. Other S-100 proteins may have clinical significance in the diagnosis of other types of cancer. For example, S-100A4 protein can be used to assess the prognosis of breast, stomach, bladder, pancreatic, and lung cancer. S-100A7 protein is a biomarker for lung and ovarian cancer. S-100A9 protein can be used for the differential diagnosis of prostate cancer and benign prostatic hyperplasia. The applicability of S-100 proteins in clinical practice has been demonstrated not only in malignant diseases but also in a wide range of other pathologies. In the brain, S-100B protein is mainly produced by astrocytes, and its increased synthesis indicates astrocyte activation in response to damage to nervous tissue due to hypoxia or hypoglycemia. Increased levels of S-100B protein in the blood and cerebrospinal fluid are observed in traumatic brain injury. It has been shown that determining the concentration of S-100B allows selecting patients with mild traumatic brain injury who actually require CT scans and avoiding unnecessary investigations by up to 30%. Scientists have found that an increase in the level of S-100B protein above 0.1 μg/L is a sensitive marker of pathological changes on CT scans of the brain. Thus, S-100 protein is a nonspecific biomarker, which is sometimes compared to C-reactive protein - another nonspecific but widely known biomarker for diseases of various eti ology. Since false-positive results for S-100 protein testing are possible, repeat analyses are recommended to avoid diagnostic errors. Careful interpretation of the results, taking into account the clinical context and other diagnostic information, is essential.
It should be noted that S-100 protein testing is not a standalone diagnostic tool but rather a complementary test that aids in the assessment and management of specific diseases. The results of the test should be interpreted by a qualified healthcare professional in conjunction with other clinical findings and diagnostic procedures.
In summary, the S-100 protein test is used in various medical specialties for the diagnosis, prognosis assessment, and treatment monitoring of certain diseases, including melanoma, neurological disorders, cardiac conditions, and autoimmune diseases. S-100 proteins have diverse functions in the body and their concentrations can change in the presence of malignant and non-malignant pathologies. However, it is important to consider that S-100 protein testing should be interpreted alongside other clinical information to ensure accurate diagnosis and appropriate patient management.
