A hemoglobin concentration of 167g/L is considered mildly high, and common causes include physiologic highs, dehydration, cardiopulmonary diseases, and true erythrocytosis. 1. Physiological high: the red blood cells and hemoglobin of the residents in the plateau area tend to be higher than those of the residents in the plain area. Drinking too little water or sweating too much can lead to temporary blood concentration, resulting in mildly elevated red blood cells and hemoglobin, and newborns may also experience physiologic elevations. 2. Dehydration: severe vomiting, diarrhea, extensive burns and advanced gastrointestinal tract tumor patients, etc. Dehydration blood concentration causes a relative increase of active ingredients in the blood. 3. Cardiopulmonary diseases: congenital heart disease, chronic lung diseases and chronic carbon monoxide poisoning, etc., due to hypoxia resulting in compensatory erythropoiesis. 4. True erythrocytosis: also known as primary erythrocytosis, is a kind of unexplained, chronic progressive bone marrow hematopoietic activity in general hyperactivity of the disease, belongs to the bone marrow tissue abnormally proliferation of neoplastic diseases. High hemoglobin may also have other causes such as myelodysplastic syndromes, etc. It is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the physician.