URINALYSIS

✓ Medically ReviewedINVESTIGATIONID: MDBT0299🚨 TRIAGE: ROUTINE

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Definition

CLINICAL DEFINITION

Urinalysis is a diagnostic investigation comprising the physical, chemical, and microscopic examination of urine. It is used to detect and quantify a wide range of substances and cellular elements, thereby aiding in the evaluation of renal, urinary tract, and systemic disorders.

IN PLAIN ENGLISH

Urinalysis is a test that looks at a sample of urine to check for signs of disease, such as infection, kidney problems, or diabetes. It helps doctors understand what is happening inside the body.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Urinalysis is NOT a urine culture. A urine culture specifically identifies and quantifies bacteria and determines their antibiotic sensitivities, whereas urinalysis screens for a broader range of chemical and cellular abnormalities.

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Word Breakdown

urin-

=urine (from Latin 'urina')

-analysis

=examination, analysis (from Greek 'analysis')

Literal Meaning: Examination of urine

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Abbreviations

UA=Urinalysis — common abbreviation used in clinical documentation and order entry.

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Synonyms & Variants

Urine Test›Urine Examination›

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Category-Specific Context

As an Investigation, urinalysis encompasses three complementary phases: gross assessment (colour, clarity, specific gravity), chemical dipstick testing (pH, protein, glucose, ketones, blood, leukocyte esterase, nitrite, bilirubin, urobilinogen), and microscopic examination of urine sediment (cells, casts, crystals, organisms). It is used to screen for, diagnose, and monitor a wide range of conditions.

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Clinical Context & Usage

CLINICAL SETTINGS

Emergency DepartmentGeneral Medicine WardNephrology Outpatient ClinicPrimary Care ClinicUrology ClinicPaediatric Ward

USAGE & DOCUMENTATION NOTES

In clinical documentation, urinalysis results are often recorded as 'UA' with a summary of dipstick findings (e.g., '+protein, +blood, negative nitrite/leukocyte esterase') and microscopy (e.g., '5–10 RBCs/hpf, no casts'). Ward rounds may reference 'urine dip' as a quick bedside test. Referral letters often include the urinalysis result alongside renal function tests. The term is also used in orders such as 'urinalysis, microscopy and culture if indicated'.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Urinalysis detects abnormalities arising from glomerular filtration, tubular reabsorption and secretion, and the structural integrity of the urinary tract. Glomerular injury increases permeability to proteins and red blood cells, manifesting as proteinuria and haematuria (often with dysmorphic red blood cells and red cell casts). Tubular damage impairs reabsorption of filtered small proteins (e.g., beta-2-microglobulin) and may produce tubular proteinuria and casts (e.g., muddy-brown granular casts in acute tubular necrosis). Infection or inflammation in the urinary tract leads to pyuria, leukocyte esterase positivity, and nitrite production by Gram-negative bacteria. Metabolic disorders such as diabetes mellitus cause glucosuria when the renal threshold for glucose reabsorption is exceeded. Obstructive or hepatocellular jaundice raises conjugated bilirubin in urine. Concentrating ability, reflected by specific gravity, indicates hydration status and renal concentrating capacity.

PRIMARY CAUSES

Glomerular disease (e.g., glomerulonephritis)

Increased glomerular permeability allows proteins and red blood cells to leak into the filtrate, producing proteinuria and haematuria, often with dysmorphic RBCs and red cell casts.

Urinary tract infection

Microbial invasion triggers pyuria (leukocyte esterase positivity) and, for nitrate-reducing organisms, nitrite positivity; bacteria and white cells are seen on microscopy.

Diabetes mellitus

When blood glucose exceeds the renal reabsorption threshold, filtered glucose remains in urine, producing glucosuria detectable by dipstick.

Acute tubular necrosis

Tubular epithelial injury impairs reabsorption and leads to muddy-brown granular casts and tubular proteinuria.

Nephrotic syndrome

Heavy glomerular protein loss produces marked proteinuria, lipiduria, and fatty casts (Maltese cross appearance).

Liver disease with conjugated hyperbilirubinaemia

Water-soluble conjugated bilirubin is filtered and excreted in urine, yielding a positive dipstick for bilirubin.

Urinary tract obstruction

Stasis predisposes to infection and may cause haematuria or crystalluria; obstruction can also reduce concentrating ability.

Physiological states (e.g., dehydration, strenuous exercise)

Dehydration raises specific gravity; strenuous exercise can cause transient proteinuria or haematuria without intrinsic renal disease.

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Epidemiology

Age Group:All age groups; commonly performed in neonates (for congenital abnormalities or metabolic screening), children (for urinary tract infection), adults (for screening and diagnosis of renal and systemic disease), and older adults (for haematuria evaluation and monitoring of chronic kidney disease).

Sex Predilection:Equal

Red Flags & Triage ★

TRIAGE LEVEL

🚨 ROUTINE

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Persistent microscopic haematuria in adults over 50 years, or visible haematuria at any age, warrants evaluation for urological malignancy; do not attribute to benign causes without appropriate investigation.
A negative dipstick does not exclude urinary tract infection when clinical suspicion is high; consider microscopy and culture.
Positive nitrite and leukocyte esterase with fever and flank pain suggests pyelonephritis and requires urgent clinical assessment and treatment.

URGENT EVALUATION TRIGGERS

Gross haematuria with clots or haemodynamic instability.
Positive nitrite and leukocyte esterase with fever and flank pain (possible pyelonephritis).
New severe hypertension with haematuria and proteinuria (possible glomerulonephritis).
Oliguria or anuria with abnormal urinalysis findings.

Contraindications & Precautions

SPECIAL PRECAUTIONS

Ensure clean-catch midstream collection to minimise contamination; process the sample promptly (within 2 hours at room temperature or refrigerate) to prevent cellular degeneration and bacterial overgrowth.
Be aware of interfering substances (e.g.
ascorbic acid
high glucose
certain medications) that can cause false-positive or false-negative dipstick results.
Interpret findings in the context of the clinical picture and confirm with microscopy or culture when indicated; do not treat asymptomatic bacteriuria in non-pregnant patients without clinical evidence of infection.

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Reference Ranges

NORMAL RANGESpecific gravity 1.001–1.035; pH 5–9; leukocyte esterase negative; nitrite negative; protein negative; blood negative; glucose negative; ketones negative; bilirubin negative; urobilinogen 0.1–1.0 mg/dL; WBC <5/hpf; RBC <3/hpf.

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Clinical Pearls

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A positive dipstick for blood with no RBCs on microscopy suggests haemoglobinuria or myoglobinuria rather than true haematuria; correlate with clinical context (e.g., rhabdomyolysis, intravascular haemolysis).

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Red cell casts are highly specific for glomerulonephritis or vasculitis and should prompt nephrology referral.

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Nitrite positivity is specific for Enterobacterales but has low sensitivity; a negative nitrite does not exclude urinary tract infection, especially with diuretic use or organisms that do not reduce nitrate.

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Specific gravity is a useful marker of hydration and renal concentrating ability but is influenced by recent fluid intake, diuretics, and radiographic contrast; interpret alongside osmolality when precision is required.

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Contamination is suggested by squamous epithelial cells ≥15–20/hpf or mixed bacterial flora; consider repeat collection or catheterised specimen when clinically indicated.

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Example Usage & SOAP

CLINICAL SENTENCE

"A 45-year-old woman presents with dysuria and frequency; urinalysis shows positive leukocyte esterase, positive nitrite, and >50 WBCs/hpf, consistent with urinary tract infection."

IN A SOAP NOTE

S: 45-year-old woman with 3 days of dysuria and urinary frequency. O: Temperature 37.8°C, suprapubic tenderness. Urinalysis: colour cloudy, specific gravity 1.020, pH 6.5, leukocyte esterase 3+, nitrite positive, protein trace, blood 1+, glucose negative, ketones negative; microscopy: >50 WBCs/hpf, 5–10 RBCs/hpf, many bacteria, squamous epithelial cells 2/hpf. A: Urinary tract infection, uncomplicated. P: Start nitrofurantoin 100 mg PO BD for 5 days; urine culture sent; review in 48 hours.

DIFFERENTIAL DIAGNOSIS CONTEXT

When urinalysis reveals haematuria, the differential includes: (1) urinary tract infection (positive nitrite/leukocyte esterase, pyuria); (2) glomerular disease (dysmorphic RBCs, red cell casts, proteinuria); (3) urolithiasis (crystaluria, colicky pain); (4) urological malignancy (persistent haematuria in older adults, smoking history); (5) contamination (squamous epithelial cells, repeat collection).

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References & Coding

LITERATURE CITATIONS & GUIDELINES

[1]Urinalysis: Reference Range, Interpretation, Collection and Panels. Medscape. 2025.

[2]Urinalysis and Urine Culture. Merck Manual. 2026.

[3]Diagnostic evaluation of the kidney and urinary tract. AMBOSS. 2026.

[4]Urinalysis Chemistry Screen and Microscopic. UChicago Medicine Medical Laboratories. 2024.

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.