What causes yellow discoloration of urine and stool?

From the Guidelines

Yellow discoloration of urine and stool is primarily caused by bilirubin, a yellow-orange pigment produced during the breakdown of red blood cells, with common causes including liver or bile duct disorders, medications, and certain foods. For urine, common causes include dehydration, which concentrates urine; medications like rifampin, phenazopyridine, and certain laxatives; B-complex vitamins; foods like carrots and beets; and liver or bile duct disorders that increase bilirubin levels 1. Yellow stool is typically normal due to bile secretion, but very pale or clay-colored stool may indicate bile duct obstruction, as seen in cases of cholangiocarcinoma or other biliary disorders 1. Certain foods like sweet potatoes, carrots, and turmeric can intensify stool's yellow color. Medical conditions affecting the liver, gallbladder, or pancreas can also alter stool color by affecting bile flow, such as in cases of pancreatic cancer or distal cholangiocarcinoma 1.

Some key points to consider include:

• Bile acid diarrhea, which can cause yellow or pale stool, is a common condition that can be diagnosed using tests such as SeHCAT or faecal bile acid measurement 1
• Liver or bile duct disorders, such as hepatitis or cirrhosis, can increase bilirubin levels and cause yellow discoloration of urine and stool 1
• Medications, such as rifampin or phenazopyridine, can also cause yellow discoloration of urine and stool 1
• Certain foods, such as carrots or beets, can intensify stool's yellow color 1
• Medical evaluation is recommended to rule out underlying conditions requiring treatment if yellow discoloration is accompanied by other symptoms like abdominal pain, jaundice, or significant changes in bowel habits 1.

It is essential to note that the most common causes of jaundice, which can lead to yellow discoloration of urine and stool, vary by geography, type of hospital, and demographics, but often include hepatitis, alcoholic liver disease, blockage of the common bile duct, and toxic reaction to a drug or medicinal herb 1. In clinical practice, a detailed history, targeted physical examination, and pertinent laboratory studies are necessary to differentiate between the various potential etiologies of jaundice and to guide further management.

From the FDA Drug Label

The patient should be told that rifampin may produce a discoloration (yellow, orange, red, brown) of the teeth, urine, sweat, sputum, and tears, and the patient should be forewarned of this.

Rifampin causes yellow discoloration of urine and possibly other bodily secretions, including sweat, sputum, and tears. However, it does not explicitly mention stool discoloration in the provided text. Therefore, a conclusion about stool discoloration cannot be drawn from this information 2.

From the Research

Causes of Yellow Discoloration of Urine and Stool

• Yellow discoloration of urine and stool can be caused by various factors, including liver function and bile duct obstruction 3, 4, 5, 6, 7
• Bile duct obstruction can lead to a buildup of bilirubin in the blood, causing yellowing of the skin, urine, and stool 3, 5
• Liver function tests, such as serum alkaline phosphatase, bilirubin, and aspartate aminotransferase, can be used to diagnose bile duct obstruction and other liver disorders 3, 4, 5, 7
• The magnitude of alkaline phosphatase, aspartate aminotransferase, and bilirubin elevation may help in the differentiation of acute and chronic biliary obstruction 5
• Endoscopic ultrasound can be used to diagnose conditions overlooked by standard diagnostic imaging in patients with common bile duct dilatation and normal liver function tests 6

Liver Function Tests and Bile Duct Obstruction

• Liver function tests can be abnormal in patients with bile duct obstruction, even if the obstruction is not complete 3, 4, 5
• The diagnostic accuracy of liver function tests, such as serum bilirubin and alkaline phosphatase, can vary depending on the cut-off values used 4
• A combination of liver function tests and imaging studies, such as ultrasound and endoscopic ultrasound, can be used to diagnose bile duct obstruction and other liver disorders 3, 4, 6

Predictors of Abnormal Recovery Pattern of Liver Function Tests

• Basal values of liver function tests, such as serum bilirubin and alkaline phosphatase, can be independent predictors of abnormal recovery pattern of liver function tests after surgical repair of bile duct strictures 7
• The degree of hepatic fibrosis can also be an independent predictor of abnormal recovery pattern of liver function tests 7