Urobilinogen in urine: what a dipstick result means

Urobilinogen belongs to the family of substances produced when the body recycles old red blood cells. Lab Tests Online UK describes the sequence in its bilirubin guide: red cells live for about 120 days, haemoglobin is released when they break down, and that haemoglobin is converted to unconjugated bilirubin. The liver processes this by adding sugars to create conjugated bilirubin, which is secreted into bile and flows into the intestine. There, bacteria break it down further, eventually producing the brown pigment that colours normal stools.

Urobilinogen is a related by-product of that bilirubin pathway between the liver and the gut, and small amounts end up in the urine. That is why a trace reading is not abnormal: Patient.info's clinical reference states plainly that a small amount of urobilinogen is normally found in urine.

The test is therefore a by-product marker, a pointer to how bilirubin is being handled between the blood, liver and gut, rather than a measurement of any one organ. That also explains why its interpretation always depends on the other lines on the strip and on how you feel.

Urobilinogen is read from a reagent strip that is dipped into a urine sample, usually at the point of care so the result is immediate. Patient.info lists ten-parameter strips as checking for leukocytes, nitrite, urobilinogen, protein, pH, blood, specific gravity, ketones, bilirubin and glucose. Lab Tests Online UK describes urinalysis as having a visual, a chemical and sometimes a microscopic phase, and says a routine urinalysis consists of the visual and chemical examinations.

Lab Tests Online UK says no test preparation is needed and that the first urine of the morning is preferred because it is more concentrated, although a sample can be collected at any time. It also advises cleaning the genital area first and collecting a midstream sample to limit contamination from skin bacteria and cells.

Your report will show how the clinic or laboratory grades the line. Because strips and reporting conventions differ, any figures or grades printed on your own report are best read against the range on that report rather than a number quoted from elsewhere.

Patient.info says that significant amounts of urobilinogen suggest further assessment for haemolytic and hepatocellular disease is indicated. Haemolytic means that red cells are being broken down faster than usual, which gives the liver and gut more bilirubin to handle. Hepatocellular refers to problems affecting liver cells themselves. A raised dipstick line is a prompt to look for these, not a statement that either is present.

The same reference notes that urobilinogen levels can be increased in conditions associated with elevated nitrite levels, for example UTIs. In a person with urinary symptoms this is why the line is read together with leukocyte esterase and nitrite rather than on its own.

Dipsticks also have limits. Patient.info observes that they become more unreliable with increasing age over 65, and Lab Tests Online UK stresses that a normal urinalysis does not mean there is no illness and that abnormal findings are a warning that should be looked at further alongside your health complaints.

• A trace or normal result is common and generally unremarkable.

• A clearly raised result may lead to blood tests for liver function and a full blood count.

• A raised result with dark urine, pale stools or yellowing of the skin or eyes is more concerning and should be reported.

• A raised result alongside cloudy urine, burning or frequency usually directs attention to infection first.

Because a little is expected, a negative reading is also common and usually has no importance. Interpretation of an absent result is more specialised and generally only matters in the context of other findings such as pale stools or jaundice, where the pathway of bilirubin from liver to gut is the question. Clinicians usually answer that with blood tests and imaging rather than by reading the dipstick.

One practical limitation is worth knowing. Patient.info lists the presence of urobilinogen and vitamin C among the factors that can cause a false negative nitrite result. In other words, the lines on the strip can interfere with one another, which is another reason the whole strip, not a single line, is interpreted.

If a raised urobilinogen is an isolated finding in someone who feels well, a clinician may simply repeat the sample, perhaps after avoiding dehydration. If it comes alongside other abnormal lines, or if symptoms such as dark urine, pale stools, itching, tiredness, nausea or abdominal pain are present, Lab Tests Online UK lists these among the reasons for a bilirubin test, usually done as part of a liver function test.

Bilirubin testing on a blood sample can separate total, conjugated and unconjugated bilirubin. Lab Tests Online UK says a high total or unconjugated level may indicate conditions in which red cells are broken down excessively, while a high conjugated level may indicate a blockage of the liver or bile ducts, hepatitis, cirrhosis, gallstones or a drug reaction. Your doctor will need further tests to find out why.

You do not need to prepare for these tests, and no special fasting is described for bilirubin. Tell your clinician about any medicines you take, because Lab Tests Online UK lists medications that affect liver function among the reasons the test is requested.