Urine

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Human Urine Sample

Editor-In-Chief: Steven C. Campbell, M.D., Ph.D., Professor of Surgery, Residency Program Director, Section of Urologic Oncology, Glickman Urological and Kidney Institute, Cleveland Clinic. You can email Dr. Campbell by clicking here. Office phone: 216-444-5595. Associate Editor(s)-in-Chief: Yazan Daaboul, M.D.
Synonyms and Keywords: Urinary findings; Urinary abnormalities; Findings on urine exam; Urine; Urine composition; Urine output

Overview

Urine is a fluid produced by humans through the kidney, collected in the bladder, and excreted through the genital urethra. Urine formation helps to maintain the balance of minerals and other substances in the body. Urinary findings may be qualitative or quantitative. Qualitative urinary findings are often analyzed on urinalysis and urine culture. Quantitative urinary findings depends on urine output. A urinalysis (U) is an array of tests performed on urine and is one of the most common methods of medical diagnosis. A part of a urinalysis can be performed by using urine dipsticks, in which the test results can be read as color changes.

Composition of Urine

Urea structure








The following is a list of normal urine constituents:

Algorithm of Common Urinary Findings

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Urinary Findings
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Quality (Composition)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Quantity (Volume)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Urinalysis
 
 
 
Urine culture
 
 
 
 
 
 
 
 
 
 
 
 
 
Urine output
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
High urine output
 
 
 
 
Low urine output
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Urine odor
 
Color and Turbidity
 
Specific gravity or osmolality
 
Urinary pH
 
Hematuria
 
Pyuria
 
Proteinuria
 
Cells
 
Casts and Crystals
 
Other
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Polyuria
 
 
Oliguria
 
Anuria
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Urine Odor

Urine is usually odorless but can produce pungent smells following the consumption of certain foods (e.g. asparagus)

Urine Color and Turbidity

Color

Below is a table that lists common urine discolorations and their associated conditions.

Urine Color Associated Conditions
Clear or Light Yellow Normal urine color
Dark Yellow Dehydration, vitamin B12 administration
Greenish/Yellow Vitamin B administration
Yellow-Red Laxatives
Orange Rifampicin, nitrofurantoin, pyridium
Dark / Black Alkaptonuria, porphyria, sarcoma
Milky Lymphatic fistulas
Opaque Bacteria, Cells
Dark Red/Pink Concentrated, hematuria, hemoglobinuria, myoglobinuria, Ingestion of certain foods (colored candy, berries, or beets)
Yellowish-Brown Hyperbilirubinemia
Pale Polyuria, chronic kidney disease
Foamy or Frothy Proteinuria
With sediment Precipitation of urate salts
Cloudy Pyuria, tissue components
With intestinal contents Intestinal fistulas

To view a complete comprehensive list of causes that are are associated with urine discoloration, click here

Turbidity

  • Normal urine is usually clear
  • Turbid urine may be a manifestation of urinary bacterial infection, hematuria, proteinuria, pyuria, or presence of crystals and casts.

Urine Specific Gravity and Osmolality

Urine Specific Gravity

  • Normal urine specific gravity (density) ranges between 1.003 and 1.035 g.cm-3.
  • Specific gravity outside the normal range may sometimes be associated with urinary disorders.

Urine Osmolality

  • In healthy individuals with restricted fluid intake, urine osmolality should be > than 800mOsm/kg.
  • 24-hour urine osmolality normally ranges between 500 and 800 mOsm/kg.
  • Random urine osmolality normally ranges between 50 and 1400 mOsm/kg.

Increased urine osmolality

Decreased urine osmolality

Urinary pH

  • The pH of urine is normally close to neutral pH = 6 to 7 (Range: 4.5 to 8.2).
  • Strongly acidic or alkaline urine may be manifestations of the following:

Renal and urologic diseases

  • Urinary tract infection
  • Acute kidney injury
  • Chronic kindey disease
  • Renal tubular acidosis

Systemic diseases

Drug administration

Hematuria

Pyuria

Proteinuria

  • Albuminuria
    • Microalbuminuria
    • Macroalbuminuria
  • Paraproteinuria

Cells

  • Benign
  • Malignant

Casts and Crystals

Casts

To view a comprehensive list of urinary cast types and the characteristics of each cast type, click here

Acellular casts

  • Hyaline casts
  • Granular casts
  • Waxy casts
  • Fatty casts
  • Pigment casts
  • Crystal casts

Cellular casts

  • RBC casts
  • WBC casts
  • Bacterial casts
  • Epithelial cell casts

Crystals

  • Struvite crystals (magnesium-ammonium-phosphate)
  • Bilirubin crystals
  • Calcium carbonate crystals
  • Amorphous crystals
  • Calcium oxalate dihydrate crystals
  • Cystine crystals

Other

Urinary beta-HCG (urinary pregnancy test)

Myoglobinuria

Glucosuria

Ketonuria

Bilirubinuria

Eosinophiluria

To view a comprehensive list of causes of eosinophiluria, click here

Bacterial antigens

Sperm

Urinary drug concentration

  • Drug testing uses urinalysis to test for certain chemicals which are typically present in the urine only after recreational drug use.
  • These tests must be requested specifically or as part of a toxicology screen, and are not part of a routine urinalysis.

Dissolved electrolytes or heavy metals

Calciuria (urinary calcium) differential diagnosis:

Catecholamines

Parameter Upper reference range in the urine per 24 hours
Norepinephrine 23-105 micrograms/24 hours
Dopamine 190-450 micrograms/24 hours
Metanephrine 74-297 micrograms/24 hours
Normetanephrine 105-354 micrograms/24 hours
Vanillic acid 3.3-6.5 mg/24 hours
Vanillyl mandelic acid 17-33 micromol/liter (3.3-6.5 mg/24 hour)

Differential Diagnosis of urinary catecholamines

Urine Culture

Normal urine is sterile. Presence of microorganisms in urine culture may be associated with urinary infections or colonization.

Urine Quantity (Volume)

  • The amount of urine produced depends on hydration (volume of fluid intake), physical activity, environmental factors, body surface area, and general health condition.
  • In adult humans, the average urine production is approximately 1 L to 2 L per 24 hours.

High Urine Output

  • Polyuria: Excessive urinary production > 2.5 L per 24 hours

Low Urine Output

Low urine output may be either oliguria or anuria:

  • Oliguria: Urine production < 400 mL / 24 hours in adults. A more specific definition includes the following:
    • Infants: oliguria is defined as urine output < 1 mL/kg/hr[1]
    • Children: Oliguria is defined as urine output < 0.5 mL/kg/hr.
    • Aduults: Oliguria is defined as urine output < 17 to 21 ml/hr.

For a detailed explanation of oliguria, click here.

  • Anuria: Urine production < 100 mL / 24 hr in adults.

For a detailed explanation of anuria, click here.

References

  1. Klahr S, Miller S (1998). "Acute oliguria". N Engl J Med 338 (10): 671–5. doi:10.1056/NEJM199803053381007. PMID 9486997. Free Full Text.

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