Why urine output decreased in cirrhosis?

Urine output decreases in cirrhosis due to several factors:

1. Low Glomerular Filtration Rate (GFR): Cirrhosis leads to a decrease in GFR, which is the rate at which blood is filtered by the kidneys. This occurs because of the increased pressure in the blood vessels of the liver (portal hypertension) which impairs blood flow to the kidneys. The reduced GFR results in less urine production.

2. Hypoalbuminemia: Cirrhosis causes a decrease in the production of albumin by the liver. Low albumin levels lead to decreased osmotic pressure in the blood, which can result in fluid retention (edema) and decreased urine output.

3. Ascites Formation: Cirrhosis often leads to the accumulation of fluid in the peritoneal cavity (ascites). This fluid buildup can further reduce GFR and decrease urine production.

4. Increased Antidiuretic Hormone (ADH) Levels: In response to fluid loss and low blood pressure associated with cirrhosis, the body releases ADH, also known as vasopressin. ADH acts on the kidneys to increase water reabsorption, leading to decreased urine output.

5. Sodium Retention: Cirrhosis can disrupt the body's sodium balance, causing the retention of sodium and water. This fluid retention contributes to ascites formation and further decreases urine output.

6. Renal Vasoconstriction: Increased levels of certain substances in cirrhosis, such as endothelin-1, can cause constriction of the renal blood vessels. This vasoconstriction reduces blood flow to the kidneys, impairing their function and reducing urine production.

7. Medications: Some medications used to treat cirrhosis, such as diuretics and beta-blockers, can also contribute to decreased urine output as side effects.

The combination of these factors leads to decreased urine output in individuals with cirrhosis, which can contribute to fluid retention, electrolyte imbalances, and other complications of the disease.