A urinalysis is a group of tests on a urine sample that screen the kidneys and urinary tract and can pick up signs of conditions elsewhere in the body, such as diabetes. It looks at three things: how the urine appears and how concentrated it is, a chemical dipstick for substances like protein, blood and sugar, and a microscope view of the cells, crystals and casts it contains.
What a urinalysis measures
Urine is the kidney’s output, so its contents mirror how the kidneys are filtering and what is passing through the urinary tract. A urinalysis reads this in three layers. The physical layer notes colour and concentration. The chemical dipstick detects protein and albumin (a marker of kidney strain), blood, glucose (a clue to diabetes), ketones, and nitrites and leukocyte esterase (pointers to infection). The microscopic layer identifies red and white blood cells, bacteria, crystals that can form stones, and casts — tiny moulds of the kidney tubules that suggest the problem is in the kidney itself. No single finding is diagnostic; the picture comes from combining them, and from following anything abnormal over time.
Which tests are included
- Urinalysis — the core dipstick-plus-microscope screen of a single sample.
- 24-Hour Urine Protein — measures total protein lost over a full day when the dipstick flags it.
- Microalbuminuria (ACR) — detects tiny amounts of albumin, the earliest sign of kidney damage in diabetes and high blood pressure.
- Urine Culture — grows and identifies bacteria to confirm a urinary tract infection and guide antibiotics.
- Urine Osmolality — measures how concentrated the urine is, used to assess hydration and how the kidneys handle water.
- Creatinine Clearance — pairs a urine collection with a blood creatinine to estimate the kidneys’ filtration rate.
Results are often reported in mg/dL or mmol/L; a unit converter helps match your report to a reference range.
When doctors order it
A urinalysis is one of the most common tests in medicine:
- Routine check-ups and pregnancy care, as a cheap, broad screen of kidney and urinary health.
- Suspected urinary tract infection — burning, frequency, urgency or flank pain — usually with a culture if infection is likely.
- Monitoring diabetes and high blood pressure, where a yearly albumin check catches early kidney damage.
- Investigating visible or dipstick blood, swelling, or unexplained tiredness that could point to the kidneys.
- Before surgery or when starting certain medications that affect the kidneys.
How to prepare
Most urine tests need no fasting. A first-morning sample is preferred where possible because it is the most concentrated, making protein and other findings easier to detect. Collection technique matters more than diet: a clean-catch midstream sample — cleaning first, then catching the middle of the stream — keeps skin cells and bacteria from muddying the result, which is especially important for a culture. Mention menstruation, as blood can enter the sample, and any recent strenuous exercise, which can push protein up briefly. Some foods, dyes and medicines (including beetroot and certain drugs) can change urine colour or dipstick readings, so tell the lab what you take.
How to read the results together
Findings are interpreted as a pattern, not one box at a time.
- Infection pattern: nitrites and leukocyte esterase positive, with white cells and bacteria under the microscope, point to a urinary tract infection — confirmed and matched to an antibiotic by a culture.
- Kidney-strain pattern: persistent protein or albumin, particularly with casts or blood and no infection, suggests the kidney’s filter is involved and prompts an albumin-to-creatinine ratio and blood tests.
- A one-off dipstick abnormality is often benign. A trace of protein or blood after exercise, fever or dehydration commonly clears on a repeat sample taken when you are well — which is why a single result is rarely acted on alone.
When to retest
It depends on the finding. A minor, isolated dipstick change is usually rechecked once, often on a first-morning sample, to see whether it persists. In diabetes and high blood pressure, an albumin-to-creatinine ratio is typically checked once a year to catch kidney damage early. A urinary tract infection is not routinely re-cultured after successful treatment unless symptoms linger or return. Persistent protein, blood or a falling filtration rate is followed on a schedule your doctor sets, alongside kidney blood tests. As always, the retest interval is one to agree with the clinician who ordered it.
