Why is urine pink?

Most urine is light yellow and does not smell strong. If the urine is pink or red, you may have hematuria. To put it simply, hematuria means that there are more red blood cells in the middle of the urine, which makes the urine appear to have changed color. Hematuria is also a disease, and we need to go to the hospital for laboratory tests in time. What causes pink urine?

Hematuria refers to ≥ 3 red blood cells per high-power microscopic field in centrifuged urine, or more than 1 red blood cell count in non-centrifuged urine or more than 100,000 in 1-hour urine, or more than 500,000 in 12-hour urine sediment, all of which indicate an abnormal increase in red blood cells in the urine and are common urinary system symptoms. The causes include urinary tract inflammation, tuberculosis, stones or tumors, trauma, drugs, etc., which have very different effects on the body. In mild cases, only an increase in red blood cells is found under the microscope, which is called microscopic hematuria; in severe cases, the appearance is like meat washing water or contains blood clots, which is called gross hematuria. Usually, when there is 1 mL of blood per liter of urine, it can be seen with the naked eye, and the urine appears red or like meat washing water.

After discovering red urine, the first thing to do is to distinguish whether it is true hematuria or false hematuria. Some drugs can cause red urine, such as aminopyrine, phenytoin sodium, rifampicin, phenol red, etc.; it needs to be distinguished from true hematuria. In recent years, there has been an increasing trend of hematuria without obvious accompanying symptoms, most of which are glomerular hematuria, which has attracted widespread attention and research.

Causes

1. Kidney and urinary tract diseases

(1) Inflammation: acute and chronic glomerulonephritis, acute and chronic pyelonephritis, acute cystitis, urethritis, urinary tract tuberculosis, urinary tract fungal infection, etc.

(2) Stones: Stones in any part of the body, such as the renal pelvis, ureter, bladder, or urethra, can scratch the urothelium as they move, which can easily cause hematuria and secondary infection. Large stones can cause urinary tract obstruction and even renal damage.

(3) Tumors Malignant tumors in any part of the urinary system or in adjacent organs that invade the urinary tract can cause hematuria.

(4) Trauma: refers to violent injury to the urinary system.

(5) Congenital malformations: polycystic kidney, congenitally thin glomerular basement membrane, nephritis, nutcracker phenomenon (this disease is caused by congenital vascular malformations that cause the left renal vein running between the abdominal aorta and the superior mesenteric artery to be squeezed, causing refractory microscopic hematuria. The right renal vein directly flows into the inferior vena cava, while the left renal vein must pass through the angle formed by the abdominal aorta and the superior mesenteric artery to flow into the inferior vena cava. Normally, this angle is 45° to 60°. If this angle is congenitally too small or filled with mesenteric fat, enlarged lymph nodes, or peritoneum, it can cause the nutcracker phenomenon. Diagnosis is mainly based on CT, B-ultrasound, and renal venography. Treatment requires surgical correction).

2. Systemic diseases

(1) Hemorrhagic diseases: thrombocytopenic purpura, allergic purpura, hemophilia, leukemia, malignant histiocytosis, aplastic anemia, etc.

(2) Connective tissue diseases: systemic lupus erythematosus, dermatomyositis, polyarteritis nodosa, scleroderma, etc.

(3) Infectious diseases: leptospirosis, hemorrhagic fever, filariasis, infectious bacterial endocarditis, scarlet fever, etc.

(4) Cardiovascular diseases: congestive heart failure, renal embolism, and renal vein thrombosis.

(5) Endocrine and metabolic diseases: gouty kidney, diabetic nephropathy, and hyperparathyroidism.

(6) Physical and chemical factors: such as food allergies, radiation exposure, drugs (such as sulfonamide, phenol, mercury, lead, arsenic poisoning, large-scale infusion of mannitol, glycerol, etc.), poisons, after exercise, etc.

3. Adjacent organ disease

Tumors from the uterus, vagina, or rectum that have invaded the urinary tract.