⚕️ Educational content only. This article explains what urinalysis measures and what the results generally indicate. It is not medical advice. Speak with your doctor or healthcare provider for interpretation in the context of your personal health.
Urinalysis (UA) — also called a urine test or dipstick test — is one of the most versatile and frequently performed tests in clinical medicine. It involves examining the physical appearance, chemical composition, and (in a full microscopy) the cellular content of a urine sample. Despite being a relatively simple and inexpensive test, urinalysis can provide important clues about kidney function, urinary tract infection, diabetes, liver disease, and several other conditions.
Key Takeaways
- Urinalysis has three components: physical assessment (colour, clarity, smell), chemical dipstick testing, and microscopic examination.
- Dipstick tests screen for protein, glucose, ketones, blood, nitrites, leukocyte esterase, bilirubin, urobilinogen, and pH.
- Protein in urine (proteinuria) is an important early marker of kidney damage, particularly in diabetes and hypertension.
- Nitrites and leukocyte esterase are the key dipstick markers of urinary tract infection (UTI).
- Glucose in urine typically indicates blood glucose above the renal threshold (≈10 mmol/L) — an important clue for undiagnosed diabetes.
- A positive dipstick result usually requires confirmation with urine microscopy and/or culture.
Physical Assessment
Normal urine is pale to dark yellow, clear, and without strong odour. Abnormal colour can indicate pathology: red or pink urine may suggest haematuria (blood), though it can also result from certain foods (beetroot) or medications; cloudy urine often indicates infection or the presence of cells and protein; very dark urine may indicate dehydration or bilirubinuria (bile pigments, suggesting liver disease); frothy urine can indicate significant proteinuria. Colour changes alone are non-specific, but they prompt further investigation.
Dipstick (Chemical) Testing
A urine dipstick is a plastic strip with chemically treated pads that change colour in the presence of specific substances. Results are read by comparing colour changes to a reference chart or using an automated reader. Key dipstick parameters include the following.
Protein: Normally, very little protein passes through the kidney’s filtration barrier. Persistent proteinuria indicates glomerular damage and is a key marker of chronic kidney disease, diabetic nephropathy, and hypertensive nephropathy. The dipstick is most sensitive to albumin. The albumin-to-creatinine ratio (ACR) on a urine sample provides a more quantitative assessment of proteinuria. Glucose: Glucose appears in urine (glycosuria) when blood glucose exceeds the kidney’s reabsorption threshold (approximately 10 mmol/L). Glycosuria can signal uncontrolled diabetes but can also occur in pregnancy (lower renal threshold) or in rare tubular disorders. Ketones: Ketones are produced when fat is broken down for energy. Ketonuria occurs in diabetic ketoacidosis (DKA), prolonged fasting, starvation, or a very low carbohydrate diet. Blood (haematuria): The dipstick detects the peroxidase activity of haemoglobin and myoglobin. True haematuria (red blood cells in urine) may indicate kidney stones, urinary tract infection, glomerulonephritis, or bladder cancer. A positive dipstick for blood must be confirmed by microscopy, as false positives occur with myoglobinuria (muscle breakdown) and haemoglobinuria. Nitrites: Many bacteria (particularly gram-negative organisms such as E. coli) convert urinary nitrates to nitrites. A positive nitrite result strongly suggests bacterial infection. Leukocyte esterase: An enzyme released by white blood cells (neutrophils). A positive result indicates pyuria (white cells in urine), suggesting infection or inflammation. Together, positive nitrites and leukocyte esterase are the key dipstick indicators of UTI. Bilirubin and urobilinogen: Bilirubin in urine indicates conjugated hyperbilirubinaemia (liver or biliary tract disease). Elevated urobilinogen occurs in haemolytic anaemia and liver disease. pH: Urine pH normally ranges from 4.5 to 8.0. Persistently alkaline urine can indicate infection with urease-producing organisms, renal tubular acidosis, or certain dietary patterns. Specific gravity: Reflects urine concentration. Low specific gravity indicates dilute urine (possible diabetes insipidus or excess fluid intake); high specific gravity indicates concentrated urine (dehydration or high ADH activity).
Urine Microscopy
When dipstick results are abnormal, urine microscopy examines the sediment after centrifugation to identify cells, casts, crystals, and organisms. Red blood cells may be dysmorphic (distorted, suggesting glomerular origin) or normal in shape (suggesting lower urinary tract bleeding). White blood cells confirm pyuria. Casts are cylindrical formations moulded in the renal tubules; red cell casts are highly specific for glomerulonephritis and are an important diagnostic finding. Bacteria seen on microscopy, combined with positive nitrites and leukocyte esterase, are strong evidence of UTI. Urine culture is required to identify the organism and determine antibiotic sensitivity.
References
- National Library of Medicine. Urinalysis. MedlinePlus. https://medlineplus.gov/lab-tests/urinalysis/
- NHS. Urine tests. https://www.nhs.uk/conditions/urine-tests/
- Simerville JA, Maxted WC, Pahira JJ. Urinalysis: a comprehensive review. American Family Physician. 2005;71(6):1153–1162.
- NICE Guideline NG109. Urinary tract infection (lower): antimicrobial prescribing. 2018.
- Kidney Disease: Improving Global Outcomes (KDIGO). Clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney International Supplements. 2013;3(1):1–150.
More questions answered
What can the urinalysis tell you, and what can it not tell you?
The urinalysis provides information about physical, chemical and microscopic features of urine. It can screen for urinary abnormalities and support kidney or metabolic assessment, but it usually cannot identify the exact cause of an abnormal value by itself. The result becomes more useful when combined with urine culture, protein measurements and kidney-related blood tests and the reason the test was requested. The main limitation is that one laboratory measurement is only part of the wider clinical picture.
Why are other blood tests often ordered with the urinalysis?
Related tests can show whether a change in the urinalysis fits a broader laboratory pattern. Measurements such as urine culture, protein measurements and kidney-related blood tests may assess connected organs, pathways or biological processes. This can help clinicians distinguish between several possible explanations for the same result. The tests are therefore complementary rather than interchangeable.
Can medicines or supplements affect the urinalysis?
Yes, some medicines or supplements can influence the urinalysis directly or indirectly, although the effect depends on the specific substance and assay. Other influences include hydration, collection quality, contamination, timing and medicines, so medication is only one possible explanation for a change. Patients should not stop prescribed treatment just to alter a laboratory result unless a healthcare professional has specifically instructed them to do so. Medication information should be shared with the healthcare team interpreting the result.
Why might a healthcare professional request another urinalysis?
A second urinalysis may be used to confirm an unexpected result, check a trend or see whether a temporary change has resolved. Repeating the test can also help when the first specimen had a quality problem or when monitoring requires measurements at different times. A repeat value is interpreted alongside the earlier result rather than treated as an unrelated number. The need for retesting depends on the clinical question.
Why might my urinalysis result be flagged at one laboratory but not another?
Laboratories can use different reference intervals or decision limits because methods, instruments, reagents and populations differ. A value near a boundary may therefore be flagged differently even when the numerical results are similar. This does not automatically mean that one laboratory made an error. Always use the range printed on the same report as the result being interpreted.
Can my urinalysis result change even when I feel the same?
Yes. Laboratory values can change because of normal biological variation, early physiological changes, medicines, hydration, timing or other factors before noticeable symptoms occur. Feeling well also does not guarantee that every laboratory measurement will sit inside its reference interval. The importance of a change depends on its size, persistence and clinical context. Personal results should be discussed with a healthcare professional when interpretation is needed.
Does a normal urinalysis rule out every related condition?
No. A result inside the reference interval does not exclude every condition related to the biological system being tested. Some disorders may not affect the marker, may affect it only at certain stages or may require other tests to detect. Clinicians therefore consider symptoms, examination and related investigations rather than using one normal value as a universal rule-out. The urinalysis should be interpreted according to the purpose for which it was ordered.
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