Normally, a high microscopic red blood cell count refers to the presence of more than 3 red blood cells in the microscopic field of urine, also known as microscopic hematuria. It needs to be considered first whether the false positive result is due to menstrual blood mixed into the urine during a woman’s menstrual period. In addition, motility hematuria may also occur if there is a sudden increase in exercise, which usually resolves on its own. After ruling it out, we need to consider urinary system diseases and diseases around the urinary system. 1, urinary system diseases 1, congenital diseases: congenital diseases resulting in abnormalities of the urinary system can lead to patients with microscopic hematuria, such as impaired glomerular filtration caused by renal hypoplasia, red blood cells are not filtered causing hematuria, which can be accompanied by abdominal masses, hypertension and other manifestations; 2, urethral injury: small urethral injury can be seen as microscopic hematuria, and large urethral injury can be seen as carnal hematuria, due to injury caused by Urethral mucosa breakage, so that small blood vessels rupture and bleed, causing hematuria, visible perineal bruising and swelling, urethral blood dripping, etc.; 3, urethral stones: stones in various parts of the urinary system can cut the urethral mucosa, triggering blood vessel rupture, appearing submicroscopic hematuria, dribbling urination and difficulty in urination; 4, urethral infection: acute and chronic glomerulonephritis due to inflammatory stimulation, glomerular filtration function decreases, unable to filter red blood cells In addition, submicroscopic hematuria can occur, often accompanied by signs of urethral irritation, such as urinary frequency, urinary urgency, painful urination, generally due to infection. Other nephritis that can also show submicroscopic hematuria include purpura nephritis, primary nephritis, lupus nephritis, etc. If accompanied by proteinuria, hypertension and other manifestations, consider the possibility of glomerulopathy; 5. Tumors: tumors in various parts of the urinary system, such as bladder cancer, ureteral cancer, pyel cancer, kidney cancer, etc., the rupture and bleeding of the lesion or invasion of surrounding tissues can cause submicroscopic hematuria, which can be accompanied by fever, malaise and other systemic symptoms; 6. Others: Microscopic hematuria can also be seen in urological tuberculosis, polyps, etc. Second, diseases around the urinary system that can cause submicroscopic hematuria include prostatitis, acute appendicitis, rectal tumors and other diseases. Among them, purulent discharge will appear in the urine of prostatitis, while acute appendicitis mostly has severe pain in the right lower abdomen. In addition, some inflammatory diseases of gynecology, such as acute pelvic inflammatory disease, tubal inflammatory disease, vaginitis, or cervical cancer may also appear the possibility of microscopic hematuria, which may have lower abdominal pain, fever, and abnormal vaginal discharge. Third, other 1, drug factors: overdose of certain drugs can damage the kidneys, which can lead to the appearance of submicroscopic hematuria, such as cyclophosphamide, heparin, sulfonamides, etc.; 2, infectious diseases: sepsis, epidemic hemorrhagic fever, scarlet fever, etc., of which, scarlet fever can cause renal metaplasia, submicroscopic hematuria, with the performance of sore throat and rash; 3, blood diseases: leukemia, hemophilia, thrombocytopenia The hemorrhage causes microscopic hematuria and can be accompanied by bleeding from multiple parts of the body such as skin and gums; 4. Autoimmune diseases: systemic lupus erythematosus, rheumatoid arthritis, etc. Among them, systemic lupus erythematosus invading the kidney can appear urinary red blood cells, and most of them will show the performance of butterfly-shaped red spots and enlarged lymph nodes; 5. Cardiovascular diseases: heart failure, renal artery embolism, etc. Renal artery embolism is due to renal artery Blockage of the renal artery causes necrosis and bleeding of the kidney, resulting in microscopic hematuria, and renal colic can also occur. In addition, prolonged exposure to oxygen deficiency or excessive water discharge, such as violent vomiting, burns, and profuse sweating, as well as pulmonary diseases, such as bronchiectasis and pulmonary heart disease, which cause insufficient pulmonary ventilation, can lead to erythrocytosis, which requires further improvement of relevant tests for clarification.