Urinalysis: what it is, what it tells you and why we do it

A urinalysis reads several things at once in one urine sample: protein, blood, sugar and signs of infection. It does not give one number but a list of readings, most of them negative or positive. It is a simple way to check your kidneys and urinary tract.

Why we do it

Every day your kidneys filter your blood and put back almost everything the body needs. That is why healthy urine holds almost no protein, blood or sugar.

When something gets through, it is often a signal: of kidneys under strain, an infection or high glucose. Sometimes it shows before blood tests change.

Two readings matter more than the rest: protein, and blood that your period does not explain.

What it tells you, and what it does not

A positive reading means there is something to understand, not a diagnosis. Exercise, fever, too little water or your period can change the result for a short while.

The strip is a quick test. If it finds something, the sediment, the urine seen under a microscope, helps show what it is.

And a negative strip does not rule everything out: it picks up protein mainly when there is a lot of it. Small amounts of albumin need another test, urine albumin.

That is why it is read together with other tests:

• Urine albumin: Picks up the albumin the strip misses
• Glucose: If there is sugar in your urine, shows whether it is high in your blood too
• Creatinine: With eGFR, shows how well your kidneys filter
• eGFR: How well your kidneys filter

Normal urinalysis results

A normal result usually looks like this. Next to each reading, your report prints the lab’s limits.

• Pale yellow or straw coloured, and clear.
• Specific gravity, how concentrated the urine is: usually between 1.003 and 1.030.
• pH, how acidic it is: from 4.5 to 8, most often slightly acidic.
• Protein, glucose, ketones, blood, nitrites and bilirubin: absent or negative.
• Leucocytes: absent, or a few under the microscope.
• Urobilinogen: normal, meaning a small amount.
• Sediment: few cells; a few crystals can appear in healthy people too.

In the Rosa report you see your urinalysis next to the rest of the panel, read together with urine albumin and your kidney tests.

If something is out of range

• Leucocytes in the urine: With positive nitrites and burning, usually an infection. Without symptoms, the sample is often just contaminated.
• Blood in the urine: It can come from your period or exercise, but also from stones or kidney or bladder problems. If your period does not explain it, talk to your doctor.
• Protein in the urine: It can appear briefly with fever, exercise or concentrated urine. If it stays, your kidneys and urine albumin are checked.

Reading by reading: what it can mean

What an out-of-range reading can mean. The cause is often temporary.

• Colour and appearance: Dark yellow usually means too little water; red, beetroot or blood; cloudy, crystals or an infection. Tea or cola coloured: see a doctor the same day.
• Specific gravity: High if you drank little, low if you drank a lot. Usually that is all it means.
• pH: It changes with what you eat: more acidic with a lot of protein, less with fruit and vegetables. It matters most for people with stones.
• Protein: It can appear briefly after exercise or with a fever. If it stays, your doctor checks urine albumin and your kidneys.
• Glucose: It usually means high blood glucose, as in diabetes. Some diabetes medicines make it appear on purpose: tell your doctor.
• Ketones: They appear when the body burns fat: with a long fast, a very low carb diet or in pregnancy. In people with diabetes they can mean glucose is out of control.
• Blood: The strip is sometimes positive without red cells, and the sediment settles it. If there is blood and your period does not explain it, your doctor looks for the cause.
• Leucocytes: They are white blood cells. In the urine they often signal an infection, especially if there is burning.
• Nitrites: Some bacteria make them in the urine. If they are positive, bacteria are usually there: what matters is whether you also have symptoms.
• Bilirubin and urobilinogen: They come from bile. If bilirubin appears, your doctor checks your liver and bile ducts.
• Sediment: The urine seen under a microscope: cells, bacteria, crystals and casts, tiny moulds of the kidneys’ small tubes. A few crystals or hyaline casts, the simplest kind, can appear in healthy people too.

How to collect your urine

How you collect the sample changes the result. In general:

• Use your first urine of the morning, the most concentrated.
• Wash your hands and use a sterile container.
• Let the first stream go into the toilet, then collect the middle part, the midstream.
• Close the container well and hand it in soon: urine left standing for long changes.
• During your period, it is best to wait a few days, or ask your lab.

With Rosa, the urine test is done at the partner lab, together with your blood draw. The lab tells you how and when to collect the sample: follow its instructions.

What can skew the result

A few things change the result for a while. It helps to know them before you read it.

• Your period: Menstrual blood gets into the sample and the blood reading turns positive. Best to collect it a few days later, or ask your lab.
• Hard exercise: A long run or a tough workout can make protein or a little blood appear for two or three days.
• A lot or a little water: With a lot of water the urine is diluted and some readings look lower. With little, it is concentrated.
• Foods and vitamins: Beetroot and blackberries can turn it red, some B vitamins bright yellow. High doses of vitamin C can skew the strip.

When to worry

Talk to your doctor if:

• You see blood in your urine, even once and even if it then goes away.
• Your report finds blood or protein away from your period and exercise.
• Your report finds glucose or bilirubin and you do not know why.
• You are pregnant and your report finds leucocytes, nitrites or bacteria.
• You have burning or need to pass urine often.
• You have diabetes and ketones in your urine: see a doctor the same day. If you also have vomiting, belly pain, fast breathing, confusion or severe drowsiness, call 112 or go to the emergency department.
• You have a fever or chills together with burning or pain in your side: see a doctor the same day.
• Your urine is the colour of tea or cola: see a doctor the same day.
• After very hard exercise you have severe muscle pain and dark urine: call 112 or go to the emergency department.
• You have a high fever and feel very unwell or confused, or you cannot pass urine: call 112 or go to the emergency department.

Frequently asked questions

What does trace mean on my report? That the strip found a tiny amount, at the edge of what it can detect. A single trace, with everything else negative, is usually nothing to worry about; if it comes back, talk to your doctor.

Do I need to fast for a urinalysis? Usually not. What matters more is using your first morning urine and collecting it well. If you do it with blood tests, follow the instructions for the blood draw.

Are a urinalysis and a urine culture the same thing? No. A urinalysis reads protein, blood, sugar and other signs. A urine culture grows the bacteria to find out which one it is and which antibiotic works. Your doctor asks for it if they suspect an infection.

Can I do a urinalysis during my period? Best not: menstrual blood turns the blood reading positive and can affect other readings. Wait a few days after it ends, or ask your lab.

Bacteria in the urine without symptoms: do they need treatment? Usually not: it is often a contaminated sample, or bacteria that cause no trouble. In pregnancy, though, always talk to your doctor.

How often should it be done? For people who feel well there is no fixed rule: Rosa does it once a year. If a reading is out of range, your doctor decides whether and when to repeat it.

Sources

• Simerville and colleagues, urinalysis: a comprehensive review. American Family Physician, 2005. PMID 15791892
• KDIGO clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney International, 2024. PMID 38490803
• Barocas and colleagues, guideline on blood in the urine seen only under the microscope, 2025 update. The Journal of Urology, 2025. PMID 40013563
• Nicolle and colleagues, guideline on bacteria in the urine without symptoms, 2019 update. Clinical Infectious Diseases, 2019. PMID 30895288