Urine analysis: Difference between revisions

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==Reference Range==
==Reference Range==
{| {{table}}
{| {{table}}
| Color||Yellow
| '''Color'''||Yellow
|-
|-
| Clarity/turbidity||Clear
| '''Clarity/turbidity'''||Clear
|-
|-
| pH||4.5-8.0
| '''pH'''||4.5-8.0
|-
|-
| Specific gravity||1.005-1.025
| '''Specific gravity'''||1.005-1.025
|-
|-
| Glucose||<130 mg/d
| '''Glucose'''||<130 mg/d
|-
|-
| Ketones||None
| '''Ketones'''||None
|-
|-
| Nitrites||Negative
| '''Nitrites'''||Negative
|-
|-
| Leukocyte esterase||Negative
| '''Leukocyte esterase'''||Negative
|-
|-
| Bilirubin||Negative
| '''Bilirubin'''||Negative
|-
|-
| Urobilirubin||Small amount (0.5-1mg/dL)
| '''Urobilirubin'''||Small amount (0.5-1mg/dL)
|-
|-
| Blood||<3 RBCs
| '''Blood'''||<3 RBCs
|-
|-
| Protein||<150mg/d
| '''Protein'''||<150mg/d
|-
|-
| RBCs||<2 RBCs/hpf
| '''RBCs'''||<2 RBCs/hpf
|-
|-
| WBCs||<2-5 WBCs/hpf
| '''WBCs'''||<2-5 WBCs/hpf
|-
|-
| Squamous epithelial cells||<15-20 per hpf
| '''Squamous epithelial cells'''||<15-20 per hpf
|-
|-
| Casts||0-5 hyaline casts/hpf
| '''Casts'''||0-5 hyaline casts/hpf
|-
|-
| Crystals||Occasionally
| '''Crystals'''||Occasionally
|-
|-
| Bacteria||None
| '''Bacteria'''||None
|-
|-
| Yeast ||None
| '''Yeast'''||None
|}
|}


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**Any acid-base abnormalities affects urinary pH
**Any acid-base abnormalities affects urinary pH
**Diet can affect pH
**Diet can affect pH
**Useful in evaluation stones, infection, RTA
**Useful in evaluation [[nephrolithiasis|stones]], [[UTI|infection]], [[renal tubular acidosis|RTA]]
***Stones: alkaline (calcium/oxalate/calcium phosphate, magnesium-ammonium phosphate, staghorn) vs acidic (uric acid, cysteine)
***[[nephrolithiasis|Stones]]: alkaline (calcium oxalate/calcium phosphate, magnesium-ammonium phosphate, staghorn) vs acidic (uric acid, cysteine)
***UTI: proteus and klebsiella produce alkaline urine
***[[UTI]]: [[proteus]] and [[klebsiella]] produce alkaline urine


*Specific gravity
*Specific gravity
**Represents kidney's ability to concentrate urine; often reflective of hydration status
**Represents kidney's ability to concentrate urine; often reflective of hydration status
**Low values can be seen in pts with impaired urinary concentrating ability (i.e. diabetic insidious, sickle cell nephropathy, acute tubular necrosis)
**Low values can be seen in patients with impaired urinary concentrating ability (i.e. [[diabetes insipidus]], [[sickle cell]] nephropathy, acute tubular necrosis)
**High values can be due to elevated protein or ketoacids
**High values can be due to elevated protein or ketoacids
**Specific gravity should be considered in detection of pediatric UTI<ref>Chaudhari PP et al. The Importance of Urine Concentration on the Diagnostic Performance of the Urinalysis for Pediatric Urinary Tract Infection. Ann Emerg Med. 2017 Feb 3. pii: S0196-0644(16)31512-8.</ref>
***The higher the concentration of the urine, when in the presence of negative LE, the higher the negative predictive value of [[UTI]]
***At threshold of greater than or equal to 5 WBCs per HPF in microscopic UA


*Glucose
*Glucose
**Glucosuria is due to high blood glucose or decreased kidney threshold concentration
**Glucosuria is due to [[hyperglycemia|high blood glucose]] or decreased kidney threshold concentration
**Typically seen in diabetics or pregnant patients
**Typically seen in [[diabetes|diabetics]] or [[pregnancy|pregnant]] patients


*Ketones
*Ketones
**Typically seen with uncontrolled diabetes, [[Diabetic ketoacidosis]], severe exercise, starvation, vomiting, pregnancy
**Typically seen with uncontrolled [[diabetes]], [[Diabetic ketoacidosis]], severe exercise, starvation, [[vomiting]], [[pregnancy]]


*Nitrite
*Nitrite
**Specific but not sensitive in detecting [[Acute cystitis]]
**90% specific but 50% sensitive in detecting [[gram negative]] bacteria that converts nitrate to nitrite
***A positive test suggest UTI but a negative test cannot rule out UTI
**A positive test suggest bacteria but a negative test cannot rule out UTI


*Leukocyte Esterase
*Leukocyte Esterase
**Enzyme within WBC that is released when WBCs lyse
**Enzyme within WBC that is released when WBCs lyse
**Typically implies [[Acute cystitis]]
**70% sensitive and 50% specific for detecting WBCs (pyuria)


*Bilirubin
*Bilirubin
**Increased urobilirubin associated with excessive hemolysis, liver disease, constipation, intestinal bacterial overgrowth
**Increased urobilirubin associated with excessive [[hemolytic anemia|hemolysis]], liver disease, [[constipation]], intestinal bacterial overgrowth
**Decreased urobilirubin associated with obstructive biliary disease and severe cholestasis
**Decreased urobilirubin associated with obstructive [[biliary disease]] and severe cholestasis


*Proteins
*Proteins
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***4+ - >1000mg/dl
***4+ - >1000mg/dl
**Etiology
**Etiology
***Transient proteinuria: CHF, fever, exercise, seizure, stress
***Transient [[proteinuria]]: [[CHF]], [[fever]], exercise, [[seizure]], stress
***Persistent proteinuria: nephrotic syndrome, glomerulonephritis, ATN, AIN, Falcon syndrome, multiple myeloma, myoglobinuria
***Persistent [[proteinuria]]: [[nephrotic syndrome]], [[glomerulonephritis]], ATN, AIN, Falcon syndrome, [[multiple myeloma]], myoglobinuria


*Blood
*Blood
**If more than 3RBCs, urine dipstick is positive for blood
**If more than 3RBCs, urine dipstick is positive for blood
**Does not detect where the blood is coming from
**Does not detect where the blood is coming from
***Can be due to hematuria, hemoglobinuria, myoglobinuria, contamination
***Can be due to [[hematuria]], hemoglobinuria, myoglobinuria, contamination
***Blood+/RBC+ --> hematuria
***Blood+/RBC+ → [[hematuria]]
***Blood+/RBC- --> myoglobinuria (rhabdomyolysis, renal failure) or hemoglobinuria (infection, transfusion-related reaction, paroxysmal nocturnal hemoglobinuria)
***Blood+/RBC- → myoglobinuria ([[rhabdomyolysis]], [[renal failure]]) or hemoglobinuria (infection, [[transfusion reaction|transfusion-related reaction]], [[paroxysmal nocturnal hemoglobinuria]])


===Microscopic Examination===
===Microscopic Examination===
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*RBCs
*RBCs
**Microscopic hematuria defined as 3RBCs/hpf or more
**Microscopic [[hematuria]] defined as 3RBCs/hpf or more
**Transient hematuria in young patients is typically benign. In older patients >50yo, warrants further work-up for underlying malignancy
**Transient [[hematuria]] in young patients is typically benign. In older patients >50yo, warrants further work-up for underlying malignancy
**Persistent hematuria always warrants further work-up
**Persistent [[hematuria]] always warrants further work-up
***Renal: glomerular (proteinuria, RBC casts, dysmorphic RBCs) vs nonglomerular (no RBC casts or dysmorphic RBCs)
***Renal: glomerular ([[proteinuria]], RBC casts, dysmorphic RBCs) vs nonglomerular (no RBC casts or dysmorphic RBCs)
***Extrarenal: tumors, stones, BPH, infections (pyelonephritis, cystitis, prostatitis, urethritis), schistosomiasis, foley trauma, anticoagulants, chemotherapy
***Extrarenal: tumors, [[nephrolithiasis|stones]], BPH, infections ([[pyelonephritis]], [[cystitis]], [[prostatitis]], [[urethritis]]), [[schistosomiasis]], foley trauma, [[anticoagulants]], chemotherapy


*Epithelial Cells
*Epithelial Cells
**Generally, 15-20 squamous cells or more indicates contamination
**Generally, 15-20 squamous cells or more indicates contamination
**Hyaline casts - nonspecific
**Hyaline casts - nonspecific
**Red cell casts - nearly diagnostic of glomerulonephritis or vasculitis
**Red cell casts - nearly diagnostic of [[glomerulonephritis]] or [[vasculitis]]
**White cell casts - tubulointerstitial nephritis, acute pyelonephritis, renal tuberculosis, vaginal infection
**White cell casts - tubulointerstitial nephritis, acute pyelonephritis, renal tuberculosis, vaginal infection
**Muddy-brown granular casts - diagnostic of acute tubular necrosis
**Muddy-brown granular casts - diagnostic of acute tubular necrosis
**Waxy and broad casts - advanced renal failure
**Waxy and broad casts - advanced [[renal failure]]
**Fatty casts - nephrotic syndrome
**Fatty casts - [[nephrotic syndrome]]


*Crystals
*Crystals
**May be normal
**May be normal
**Calcium oxalate crystals - ethylene glycol ingestion
**Calcium oxalate crystals - [[ethylene glycol]] ingestion
**Uric acid crystals - tumor lysis syndrome, gout
**Uric acid crystals - [[tumor lysis syndrome]], [[gout]]
**Cystine crystals - cystinuria
**Cystine crystals - cystinuria
**Magnesium ammonium phosphate and triple phosphate crystals - UTI caused by Proteus, Klebsiella
**Magnesium ammonium phosphate and triple phosphate crystals - [[UTI]] caused by [[Proteus]], [[Klebsiella]]


*Bacteria
*[[Bacteria]]
**Generally due to infection or contamination
**Generally due to infection or contamination
**If positive for nitrites, leukocyte esterase and bacteria - highly suggestive of UTI
**If positive for nitrites, leukocyte esterase and bacteria - highly suggestive of [[UTI]]
**If significant amount of squamous epithelial cells - may indicate contamination
**If significant amount of squamous epithelial cells - may indicate contamination
**Urine culture should be obtained if UTI suspected
**Urine culture should be obtained if UTI suspected
***Generally, >100K/mL of a single organism reflects significant bacteriuria  
***Generally, >100K/mL of a single organism reflects significant bacteriuria  


*Yeast
*[[candiduria|Yeast]]
**Generally due to infection or contamination
**Generally due to infection or contamination


===See Also===
==See Also==


===References===
 
==References==
<references/>
<references/>
*Edgar, L. emedicine.medscape.com/article/2074001
 
[[Category:Renal]]
[[Category:Urology]]

Latest revision as of 18:13, 16 October 2019

Reference Range

Color Yellow
Clarity/turbidity Clear
pH 4.5-8.0
Specific gravity 1.005-1.025
Glucose <130 mg/d
Ketones None
Nitrites Negative
Leukocyte esterase Negative
Bilirubin Negative
Urobilirubin Small amount (0.5-1mg/dL)
Blood <3 RBCs
Protein <150mg/d
RBCs <2 RBCs/hpf
WBCs <2-5 WBCs/hpf
Squamous epithelial cells <15-20 per hpf
Casts 0-5 hyaline casts/hpf
Crystals Occasionally
Bacteria None
Yeast None

Collection

  • Midstream urine specimen should be collected in clean container
  • Women should clean external genitalia before voiding to avoid contamination
  • Urine specimen should be analyzed within 30-60min for accurate results

Analysis

Gross Visual Examination

  • Clarity/turbidity
    • Determined by substances in urine, including cellular debris, casts, crystals, bacteria, proteinuria, vaginal discharge, sperm

Chemical Examination

  • pH
    • Slightly acidic urine is normal
    • Any acid-base abnormalities affects urinary pH
    • Diet can affect pH
    • Useful in evaluation stones, infection, RTA
      • Stones: alkaline (calcium oxalate/calcium phosphate, magnesium-ammonium phosphate, staghorn) vs acidic (uric acid, cysteine)
      • UTI: proteus and klebsiella produce alkaline urine
  • Specific gravity
    • Represents kidney's ability to concentrate urine; often reflective of hydration status
    • Low values can be seen in patients with impaired urinary concentrating ability (i.e. diabetes insipidus, sickle cell nephropathy, acute tubular necrosis)
    • High values can be due to elevated protein or ketoacids
    • Specific gravity should be considered in detection of pediatric UTI[1]
      • The higher the concentration of the urine, when in the presence of negative LE, the higher the negative predictive value of UTI
      • At threshold of greater than or equal to 5 WBCs per HPF in microscopic UA
  • Nitrite
    • 90% specific but 50% sensitive in detecting gram negative bacteria that converts nitrate to nitrite
    • A positive test suggest bacteria but a negative test cannot rule out UTI
  • Leukocyte Esterase
    • Enzyme within WBC that is released when WBCs lyse
    • 70% sensitive and 50% specific for detecting WBCs (pyuria)
  • Bilirubin
    • Increased urobilirubin associated with excessive hemolysis, liver disease, constipation, intestinal bacterial overgrowth
    • Decreased urobilirubin associated with obstructive biliary disease and severe cholestasis

Microscopic Examination

  • WBCs
    • Elevated WBCs indicate infection, inflammation or contamination
  • Epithelial Cells
    • Generally, 15-20 squamous cells or more indicates contamination
    • Hyaline casts - nonspecific
    • Red cell casts - nearly diagnostic of glomerulonephritis or vasculitis
    • White cell casts - tubulointerstitial nephritis, acute pyelonephritis, renal tuberculosis, vaginal infection
    • Muddy-brown granular casts - diagnostic of acute tubular necrosis
    • Waxy and broad casts - advanced renal failure
    • Fatty casts - nephrotic syndrome
  • Bacteria
    • Generally due to infection or contamination
    • If positive for nitrites, leukocyte esterase and bacteria - highly suggestive of UTI
    • If significant amount of squamous epithelial cells - may indicate contamination
    • Urine culture should be obtained if UTI suspected
      • Generally, >100K/mL of a single organism reflects significant bacteriuria
  • Yeast
    • Generally due to infection or contamination

See Also

References

  1. ↑ Chaudhari PP et al. The Importance of Urine Concentration on the Diagnostic Performance of the Urinalysis for Pediatric Urinary Tract Infection. Ann Emerg Med. 2017 Feb 3. pii: S0196-0644(16)31512-8.
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