High fibrinogen concentrations can be caused by physiologic reasons or by pathologic reasons. 1. Physiological reasons: long-term smokers, as well as women after pregnancy and during menstruation, are likely to lead to high concentrations of fibrinogen. In addition, after strenuous exercise, as well as older people, women taking estrogenic drugs, may also lead to high fibrinogen concentrations. 2. Pathological causes: high fibrinogen concentration may also be caused by diseases, such as: malignant tumors, acute hepatitis, rheumatism, myocardial infarction, hypertension, as well as nephrotic syndrome, diabetes mellitus and so on. Fibrinogen concentration is high need to determine the specific causes, it is recommended to go to the hospital in a timely manner, follow the doctor’s instructions for treatment.