A standard urine dipstick has 10 small colored pads, each designed to detect a different substance. After the strip is dipped in urine, each pad changes color based on what it finds. You then compare those colors to a chart printed on the test bottle. The tricky part is that every pad uses a different color scale, and some need to be read at different times to be accurate.
How the Color Chart Works
Each pad on the strip starts as one color and shifts along a gradient depending on how much of a substance is present. The further the color moves from the “negative” end of the scale, the higher the concentration. Results are typically reported as negative, trace, 1+, 2+, 3+, or sometimes 4+. The color chart on your test bottle is the only reliable reference, since exact shades vary between manufacturers.
Timing matters more than most people realize. Different pads need different wait times before you read them. Glucose and bilirubin should be read at 30 seconds. Ketones at 40 seconds. Blood, pH, protein, urobilinogen, and nitrite all need 60 seconds. Leukocytes take the longest at a full 2 minutes. Reading too early or too late can give you a misleading color.
pH: Yellow to Green to Blue
The pH pad measures how acidic or alkaline your urine is, on a scale from about 5.0 to 9.0. The color runs from yellow or orange at the acidic end (pH 5.0) through green at neutral (pH 7.0) to blue at the alkaline end (pH 9.0). Most people’s urine falls between 5.5 and 7.0. A very alkaline reading can sometimes indicate a urinary tract infection, while consistently acidic urine may be linked to diet, dehydration, or certain metabolic conditions.
Specific Gravity: Concentration at a Glance
This pad tells you how concentrated your urine is. Dilute urine (from drinking a lot of water) produces a different color than concentrated urine (from dehydration). The normal range sits between about 1.005 and 1.030. A reading at the low end suggests your body has plenty of fluid. A high reading means your urine is very concentrated, which can happen with dehydration, heavy sweating, or reduced fluid intake.
Leukocytes and Nitrites: Signs of Infection
These two pads work as a team. Leukocytes are white blood cells, and their presence in urine suggests your immune system is fighting something in the urinary tract. The pad shifts color as the concentration of white blood cells increases. Nitrites appear when certain bacteria convert naturally occurring nitrates in your urine into nitrites. A color change on the nitrite pad is a strong signal of a bacterial urinary tract infection.
If both pads change color, infection is very likely. However, not all bacteria produce nitrites, so a negative nitrite result doesn’t completely rule out infection, especially if the leukocyte pad is positive. The leukocyte pad takes the longest to develop (2 minutes), so reading it too early is a common source of false negatives.
Protein: A Window Into Kidney Health
The protein pad typically shifts from yellow (negative) toward progressively deeper shades of green as protein levels rise. Healthy kidneys filter protein out of urine, so anything above trace amounts can signal that the kidneys aren’t filtering properly. Temporary spikes can happen after intense exercise, fever, or stress, but persistent protein in urine warrants further testing for conditions like kidney disease or high blood pressure-related kidney damage.
Blood: Speckled vs. Solid Color
The blood pad detects both intact red blood cells and free hemoglobin (the oxygen-carrying molecule inside those cells). On some strips, scattered green dots on the pad indicate intact red blood cells, while a uniform color change suggests free hemoglobin or damaged red blood cells. Blood in urine can come from infections, kidney stones, vigorous exercise, or more serious conditions affecting the kidneys or bladder. Even a trace positive result is worth following up on if it persists.
Glucose: When Sugar Spills Over
Normally, your kidneys reabsorb all the glucose that passes through them, so the glucose pad should stay negative. When blood sugar climbs high enough, the kidneys can’t keep up, and glucose “spills” into the urine. Most dipsticks detect glucose starting around 100 mg/dL in urine, with the color deepening through trace, 1+, 2+, 3+, and sometimes 4+ categories, spanning a range up to about 2,000 mg/dL. A positive result is most commonly associated with uncontrolled diabetes, though it can also occur during pregnancy or with certain kidney conditions that lower the threshold at which glucose escapes into urine.
Ketones: From Fasting to Emergency
Ketones show up in urine when your body burns fat instead of glucose for energy. The pad progresses through color shades (often from beige or light pink toward deeper purple or maroon) as ketone levels rise from negative to small, moderate, and large. Small amounts can appear during fasting, low-carb diets, or after prolonged exercise. Moderate to large ketones in someone with diabetes, however, can signal diabetic ketoacidosis, a dangerous condition where the blood becomes too acidic. This combination of high glucose and high ketones on a dipstick is a red flag that needs immediate attention.
Bilirubin and Urobilinogen: Liver and Bile Clues
These two pads help assess liver function and bile flow. Bilirubin is a waste product from the normal breakdown of red blood cells. It’s processed by the liver and shouldn’t normally appear in urine. A positive bilirubin pad suggests that bile isn’t flowing properly or that the liver is under stress, potentially from hepatitis, cirrhosis, or a blocked bile duct.
Urobilinogen is produced when bacteria in the intestines break down bilirubin. A small amount in urine is normal. High levels can point to liver disease (hepatitis, cirrhosis, medication-related liver damage) or hemolytic anemia, a condition where the body destroys red blood cells faster than it can replace them. Very low or absent urobilinogen may indicate a blockage in the bile ducts or reduced blood flow through the liver.
What Can Throw Off Your Results
Several things can cause misleading colors on a dipstick. Certain medications turn urine bright orange, red, or brown, which can make it harder to read the pads accurately. Vitamin C supplements can interfere with the glucose and blood pads, sometimes masking a true positive. A urine sample that sits too long before testing may give inaccurate readings, especially for bilirubin (which breaks down in light) and nitrites (which can develop from bacterial contamination outside the body).
Highly concentrated or deeply pigmented urine can also tint the pads and make color comparisons difficult. If you’re using an at-home strip, testing with a fresh midstream sample in good lighting gives you the most reliable read. And always compare colors at the correct time interval for each pad rather than reading the whole strip at once.