Urinalysis results explained: what every line means and which flags matter

Most flags on a routine urinalysis are prompts to repeat or confirm the result, not findings. That includes trace protein, a small amount of blood and positive leukocyte esterase. Many trace back to concentrated urine, a hard workout, a period or a contaminated sample. The report comes in three parts: the look, the dipstick and the microscope. A few results do need prompt care, and each one is flagged below where it comes up.

Normal urine runs from pale straw to dark amber, and the shade mostly tracks how concentrated the urine is. Beets, blackberries, some medicines (rifampin, phenazopyridine) and B-vitamin supplements can turn urine red, orange or bright yellow without any disease ¹. Cloudy urine often comes from harmless phosphate or urate crystals that form as the sample cools, though white cells and bacteria can also cloud it ¹. The urine color and urine clarity pages cover the full list of shades.

Specific gravity: the number that explains the other numbers

Urine specific gravity compares the density of urine with the density of water. In healthy people it ranges from about 1.003 to 1.030, and it swings through the day with how much you drink and sweat ¹. A first-morning sample, collected after a night without fluids, is usually the most concentrated urine of the day. The dipstick pads read concentration, so specific gravity is the context for every pad that follows. A high reading can push protein or blood up a grade, and a reading near 1.005 can dilute them below the strip's detection limit.

How the sample was collected

How the sample was collected changes the result. A clean-catch midstream sample cuts down skin cells and bacteria from outside the urinary tract: clean the area, let the first part of the stream go, then catch the middle ¹. Squamous epithelial cells are the flat cells that line the skin and the outer urethra. Many of them on the report mark the sample as likely contaminated, which makes its bacteria, white-cell and blood flags less trustworthy ¹. The squamous epithelial cells page covers the counts. Menstrual blood often turns the blood pad positive, and the usual step is to repeat the test after the period ends ².

The dipstick is a plastic strip with small pads of reagent. Each pad changes color in response to one substance. After a set number of seconds, a machine or a technician reads the color against a chart ¹. The strip is fast and cheap, and it is built to flag possible problems, so it gives up some accuracy for speed. The table below shows what each pad detects and what usually comes next.

Sources for the table: pad chemistry, normal ranges and false positives come from the American Family Physician urinalysis review ¹, the red-cell cutoff from the AUA microhematuria guideline ², the ACR step from KDIGO ⁴ and the SGLT2 effect from the drug label ⁷. Each pad has its own page: pH, glucose, ketones, blood, bilirubin, urobilinogen, nitrite and leukocyte esterase. High-dose vitamin C can make the blood and glucose pads read falsely negative, so tell whoever orders the test about any supplements you take ¹.

Trace and 1+ protein

Trace or 1+ protein on a single dipstick is common and often temporary. Exercise, fever, dehydration and long hours on your feet can each raise the protein pad for a day or two ¹. Albumin is the main protein in blood. Albumin leaking into urine is called albuminuria, and many reports still print the older word microalbumin; see urine albumin and microalbumin. The protein pad has a blind spot at the low end. Its detection limit sits above most of the moderately increased albuminuria range (albumin leaking at 30 to 300 mg per gram of creatinine), so a negative protein dipstick does not rule out early kidney damage ⁴.

The urine protein on the dipstick page covers the full grade ladder from trace to 4+, the false positives, and protein that appears only after standing. The confirming test is a urine ACR or a urine protein-to-creatinine ratio on a repeat sample, and KDIGO prefers an early-morning sample for both ⁴. When protein is heavy, some clinicians order a 24-hour urine protein collection.

Blood on the dipstick versus red cells under the microscope

The blood pad changes color when hemoglobin, the red protein inside red blood cells, reacts with a chemical on the pad. Free hemoglobin from red cells that burst in the sample turns the pad positive too, and so does myoglobin, a protein released from damaged muscle. So a positive blood pad with no red cells on microscopy points away from bleeding in the urinary tract ¹. The American Urological Association (AUA) defines microscopic blood, called microhematuria, as 3 or more red blood cells per high-power field on a properly collected sample ².

Clinicians should not define microhematuria by positive dipstick testing alone. A positive urine dipstick test (trace blood or greater) should prompt formal microscopic evaluation of the urine.Barocas DA et al., Microhematuria: AUA/SUFU Guideline, J Urol 2020

If a temporary cause is likely, such as a period, a hard workout or a recent infection, the test is usually repeated once that cause has passed. Beyond that, the AUA guideline sorts people into low, intermediate and high risk by age, sex, smoking history, the red-cell count and any past visible blood ². Low risk often means a repeat urinalysis within 6 months, or a discussion of further tests. Intermediate risk usually means a camera look inside the bladder (cystoscopy) and a kidney ultrasound. High risk usually means cystoscopy plus a CT scan of the urinary tract ². The urine red blood cells page covers the counts in detail.

Nitrite, leukocyte esterase and bacteria

The nitrite pad turns positive when certain bacteria have sat in the bladder long enough to convert nitrate to nitrite, usually at least 4 hours ¹. A positive nitrite is fairly specific for bacteria. Many infections still test negative, so a negative nitrite does not rule one out ¹. Leukocyte esterase signals white blood cells. That means inflammation somewhere along the urinary tract, or a sample contaminated with vaginal secretions ¹. Reports often show positive leukocyte esterase with a negative nitrite. That pairing can be a real infection with bacteria that do not make nitrite, a contaminated sample, or inflammation without infection.

Symptoms decide what these flags mean. Bacteria in the urine of someone with no urinary symptoms is called asymptomatic bacteriuria. The Infectious Diseases Society of America (IDSA) recommends against screening for it or treating it in most non-pregnant adults ³. The main exceptions are pregnancy and a planned urologic procedure that may cause bleeding ³. Under this guideline, urine bacteria or white cells found on a routine urinalysis in someone with no burning, urgency or fever are often not treated. Your clinician decides whether you need treatment. Do not stop a prescribed antibiotic without talking to them.

Glucose and ketones

Glucose usually appears on the dipstick once blood glucose rises above the kidneys' threshold of roughly 180 mg/dL ¹. A positive urine glucose therefore points to blood sugar, and the usual next step is a fasting glucose or an HbA1c. If those come back slightly high, prediabetes explains what that range means and what helps. SGLT2 inhibitors such as empagliflozin (Jardiance) and dapagliflozin (Farxiga) cause a positive glucose pad by design. These drugs lower blood sugar by making the kidneys pass glucose into the urine ⁷. Blood sugar explained covers the blood side. Ketones are byproducts of burning fat. Fasting, a low-carbohydrate diet, vomiting and endurance exercise can all turn the ketone pad positive with no illness behind it.

Bilirubin should be absent from urine. A positive bilirubin pad suggests a problem in the liver or bile ducts, and the follow-up is blood liver tests. Small amounts of urobilinogen are normal ¹.

Many labs run urine microscopy only when the clinician orders it or when a dipstick pad is positive (a reflex test). A technician spins the urine down and counts what settles at the bottom. Counts are given per high-power field (HPF, the view at about 400 times magnification) or per low-power field (LPF) ¹. Casts are tube-shaped plugs that form inside the kidney's tubules and wash out intact, so they show that something happened inside the kidney itself.

Cutoffs come from the AUA guideline ² and the American Family Physician review ¹, and the bacteria row follows IDSA ³. For detail, see hyaline casts, granular casts, crystals and yeast.

What a urinalysis cannot tell you about your kidneys

A urinalysis is a weak screen for early kidney damage. The protein pad misses most moderately increased albuminuria, and a urinalysis says nothing about how much blood the kidneys filter ⁴. KDIGO, the international kidney guideline group, defines chronic kidney disease using two numbers. eGFR (estimated glomerular filtration rate) shows how much the kidneys filter, and urine ACR shows whether the filter leaks. An ACR of 30 mg/g or more lasting over 3 months counts even when eGFR is normal ⁴. The urine ACR divides albumin by urine creatinine from the same sample, which cancels out how dilute the urine is. One raised ACR is not a diagnosis. The ADA counts albuminuria only when 2 of 3 samples collected over 3 to 6 months are raised ⁵.

The American Diabetes Association (ADA) advises checking urine ACR and eGFR at least once a year in everyone with type 2 diabetes from diagnosis, and in type 1 diabetes once it has lasted 5 years ⁵. KDIGO also recommends testing people with high blood pressure and other kidney risks ⁴. Kidney function explained and chronic kidney disease cover the full picture, including serum creatinine and cystatin C.

How the test works in practice

• No fasting is needed. A random sample works for a routine urinalysis, and a first-morning sample is preferred when protein or ACR is the question ⁴.
• A urinalysis, a urine ACR and a urine culture are three separate orders. A standard urinalysis does not include ACR, so ask for it by name if kidney screening is the goal.
• A urinalysis is one of the cheaper lab tests. Insurance usually covers it when a clinician orders it for a reason, such as urinary symptoms, pregnancy care, a planned procedure or a physical.
• Tell the lab or clinician about a period, a hard workout in the past day or two, a fever, and any vitamin C or B-vitamin supplements, since each can change the pads ¹.

Repeat, confirm or call: sorting your flags

1. 1Check the contextLook at specific gravity and the squamous cell count. Also note whether the sample followed a period, hard exercise, a fever or dehydration. Any of these can explain a single flag, but only your clinician can rule out other causes, so do not dismiss a flag on your own.
2. 2Repeat what was borderlineTrace protein, a small amount of blood, or white cells in a contaminated sample are often repeated on a clean-catch sample, ideally first-morning, once the likely cause has passed. That can mean a couple of days after hard exercise, a few days after a period ends, or after a fever or infection has cleared. Your clinician decides whether and when to repeat.
3. 3Confirm with the right testProtein goes to a urine ACR or protein-to-creatinine ratio, and blood goes to microscopy. Nitrite or leukocyte esterase with symptoms goes to a culture, and glucose goes to a blood glucose or HbA1c.
4. 4Call promptly for the red flagsThe warning boxes above list the red flags: visible blood, fever with flank pain, 3+ protein with swelling, and glucose plus ketones when unwell. Each needs a clinician soon. Glucose plus ketones in diabetes is an emergency. Without known diabetes, it needs same-day care.

Reference ranges differ slightly between strip makers and labs, so read your report against its own printed range. Reference ranges explained and how to read any lab result walk through the method. Lab units explained decodes mg/dL, mg/g and per-HPF counts. Trends beat single readings explains why a repeat matters more than one strip. Every urine marker is collected on the urine topic page, and kidney tests are on the kidney topic page.

LifeFrom explains lab results for general education. It is not a medical provider, and this page is not medical advice, a diagnosis or a treatment plan. Talk to a licensed clinician about your results before making any health decision. If you think you have a medical emergency, call your local emergency number.

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