Bilirubin and Urobilinogen: The Two Liver Pads on a Urine Strip

Most people never look at these two pads. Together they give a rough read on bile flow and red cell turnover, and one of them is a same week phone call when positive.

Of the ten pads on a standard urine strip, bilirubin and urobilinogen are the two that most home users skip. They are also the two that tell you something about the liver and the blood, which nothing else on the strip does. Here is how to read them.

Where the pigments come from

Red blood cells live about 120 days. When they are broken down, the hemoglobin inside them is converted to bilirubin, a yellow pigment. The liver takes up bilirubin, processes it, and sends it into bile, which flows into the gut.

In the gut, bacteria convert bilirubin into urobilinogen. Most of it leaves in stool, where it gives stool its brown color. A small amount is reabsorbed into the blood and some of that is filtered into urine. So a little urobilinogen in urine is normal. Bilirubin in urine is not.

The bilirubin pad

Normal: negative.

Bilirubin in urine means processed bilirubin is backing up into the blood instead of flowing out through bile. The usual causes are a blockage in the bile ducts, from a gallstone or a tumor, or liver cell damage from hepatitis, drugs, or alcohol that impairs bile secretion.

A positive bilirubin pad often comes before jaundice is visible. The urine may look dark or tea colored. Shaking a sample produces a yellow foam. Stools may be pale, because the bilirubin that should have colored them is going the wrong way.

A positive bilirubin pad is a reason to have blood tests within days. Liver enzymes, total and direct bilirubin, and alkaline phosphatase will show whether the problem is the liver cells or the ducts. With pain, fever, or visible jaundice, it is a same day call.

Things that skew it. The pad degrades in light. A strip left in an open bottle in a bright bathroom loses sensitivity. Urine left standing loses bilirubin too, so test fresh. Some drugs, including phenazopyridine, the urinary pain reliever, color urine orange and can cause a false positive. Large doses of vitamin C can cause a false negative.

The urobilinogen pad

Normal: 0.2 to 1.0 mg/dL, sometimes written as "normal."

This pad is unusual because both high and absent can be abnormal.

High urobilinogen means more bilirubin than usual is reaching the gut and being recycled. Two causes: the liver is not clearing recycled urobilinogen well, as in hepatitis or cirrhosis, or red cells are being destroyed faster than normal, as in hemolytic anemia, so more bilirubin is being made in the first place. High urobilinogen with a negative bilirubin pad points toward hemolysis. High urobilinogen with a positive bilirubin pad points toward liver disease.

Absent urobilinogen means bilirubin is not reaching the gut at all. That is the pattern of a complete bile duct blockage. It can also follow a course of antibiotics that wiped out the gut bacteria that make urobilinogen. Most strips cannot read true zero, so "absent" is usually a lab finding rather than a home one.

Things that skew it. Urobilinogen is unstable in light and in standing urine. Test fresh. Some drugs cause false positives, including sulfonamides. Nitrite in the sample can suppress the reaction and cause a false negative.

Reading the two together

Bilirubin	Urobilinogen	Likely direction
Negative	Normal	Nothing to see
Negative	High	Increased red cell breakdown, or early liver impairment
Positive	High	Liver cell disease (hepatitis, cirrhosis)
Positive	Low or absent	Bile duct obstruction

This is a rough map, not a diagnosis. The blood tests decide.

What these pads are not

They are not a fatty liver test. Fatty liver, the most common liver condition in the US, does not put bilirubin in urine until it is very advanced. A normal bilirubin pad says nothing about fat or early scarring. That question needs blood enzymes and, for people at risk, a FIB-4 score. See the liver health checkup and liver enzymes explained.

They are also not a hepatitis screen. Hepatitis B and C are usually silent and need a blood test to find.

What to do with a result

Bilirubin negative, urobilinogen normal: nothing.

Urobilinogen mildly high, once: repeat on fresh first morning urine. If it persists, mention it at a visit; a blood count and liver enzymes will sort out which direction it points.

Bilirubin positive, once: repeat immediately on a fresh sample. If positive again, book blood tests within the week.

Bilirubin positive with dark urine, pale stool, yellow eyes, abdominal pain, or fever: call a clinician today.

For the full ten pad reference, see what a 10 parameter dipstick measures.

By the Ribbon Health Press editorial team. Reviewed against current clinical guidelines at publication. Report an error: editors@ribboncheckup.org. See our editorial policy.