Urinalysis

Summary

Urinalysis is a common laboratory test that evaluates the physical, chemical, and microscopic properties of urine. It is used to assess renal function, diagnose urinary tract infections, and monitor various medical conditions. The test involves the collection of a urine sample, which is then analyzed for various components, including color, clarity, specific gravity, pH, protein, glucose, ketones, bilirubin, urobilinogen, nitrites, leukocyte esterase, and microscopic elements such as red blood cells, white blood cells, epithelial cells, casts, and crystals. Interpretation of urinalysis results requires an understanding of normal values and the clinical context in which the test is performed.

Normal Values

• Color: Pale yellow to amber
• Clarity: Clear
• Specific Gravity: 1.005-1.030
• pH: 4.6-8.0
• Protein: Negative
• Glucose: Negative
• Ketones: Negative
• Bilirubin: Negative
• Urobilinogen: 0.2-1.0 mg/dL
• Nitrites: Negative
• Leukocyte Esterase: Negative
• Red Blood Cells: 0-2 per high-power field (HPF)
• White Blood Cells: 0-5 per high-power field (HPF)
• Epithelial Cells: Few
• Cast: None
• Crystals: None
• Bacteria: None
• Yeast: None
• Parasites: None
• Mucus: None
• Trichomonas: None

Physical Properties

Color

Clarity

Specific Gravity

Chemical Properties

pH

Protein

Urinalysis Finding	Associated Diseases/Conditions	Details
Proteinuria	Nephrotic syndrome, glomerulonephritis, preeclampsia	Excessive protein in urine due to kidney damage or increased permeability of the glomeruli.
Hematuria	Urinary tract infections (UTIs), kidney stones, trauma, malignancies	Presence of red blood cells in urine; may indicate injury or disease of the urinary tract.
Pyuria	UTIs, interstitial nephritis, sexually transmitted infections (STIs)	Presence of white blood cells in urine, often indicative of infection or inflammation.
Nitrites	Bacterial infections (e.g., UTIs caused by gram-negative bacteria)	Nitrite-positive results suggest bacteria that reduce nitrates to nitrites.
Leukocyte esterase	UTIs, pyelonephritis	Indicates the presence of white blood cells and potential infection.
Glucosuria	Diabetes mellitus	Glucose in urine occurs when blood glucose exceeds the renal threshold (~180 mg/dL).
Ketonuria	Diabetic ketoacidosis, starvation, prolonged fasting	Indicates fat metabolism due to insufficient glucose availability.
Bilirubin	Liver diseases (e.g., hepatitis, cirrhosis), biliary obstruction	Presence in urine suggests impaired liver function or bile duct obstruction.
Urobilinogen	Hemolytic anemia, liver diseases	Elevated levels suggest increased bilirubin turnover or liver dysfunction.
Specific gravity (high)	Dehydration, heart failure	High specific gravity indicates concentrated urine due to low fluid intake or other factors.
Specific gravity (low)	Diabetes insipidus, renal tubular damage	Low specific gravity suggests dilute urine due to inability to concentrate urine.
pH (acidic)	Diabetic ketoacidosis, diarrhea, starvation	Acidic urine may result from metabolic acidosis or high-protein diets.
pH (alkaline)	UTIs, renal tubular acidosis, vegetarian diet	Alkaline urine may indicate infection or metabolic alkalosis.
Casts	Glomerulonephritis (RBC casts), pyelonephritis (WBC casts), nephrotic syndrome (fatty casts)	Casts are formed in the renal tubules and reflect kidney pathology.
Crystals	Kidney stones (calcium oxalate, uric acid), gout	Crystal types suggest specific conditions like gout or risk of stone formation.
Blood (false positives)	Menstruation, myoglobinuria	Contamination or non-urinary sources of red coloration.
Bacteria	UTIs	Presence indicates infection; may be accompanied by nitrites or leukocyte esterase.