Urine analysis: Difference between revisions
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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 | **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> | **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> | ||
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*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 | ||
**90% specific but 50% sensitive in detecting gram | **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 | **A positive test suggest bacteria but a negative test cannot rule out UTI | ||
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*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 | ||
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
- Color
- Normal color varies from pale light yellow to dark amber
- See Abnormally colored urine
- 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
- Glucose
- Glucosuria is due to high blood glucose or decreased kidney threshold concentration
- Typically seen in diabetics or pregnant patients
- Ketones
- Typically seen with uncontrolled diabetes, Diabetic ketoacidosis, severe exercise, starvation, vomiting, pregnancy
- 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
- Proteins
- Urine dipstick become positive the protein >300-500mg/d
- Trace - 10-30mg/dl
- 1+ - 30mg/dl
- 2+ - 100mg/dl
- 3+ - 300 mg/dl
- 4+ - >1000mg/dl
- Etiology
- Transient proteinuria: CHF, fever, exercise, seizure, stress
- Persistent proteinuria: nephrotic syndrome, glomerulonephritis, ATN, AIN, Falcon syndrome, multiple myeloma, myoglobinuria
- Urine dipstick become positive the protein >300-500mg/d
- Blood
- If more than 3RBCs, urine dipstick is positive for blood
- Does not detect where the blood is coming from
- Can be due to hematuria, hemoglobinuria, myoglobinuria, contamination
- Blood+/RBC+ → hematuria
- Blood+/RBC- → myoglobinuria (rhabdomyolysis, renal failure) or hemoglobinuria (infection, transfusion-related reaction, paroxysmal nocturnal hemoglobinuria)
Microscopic Examination
- WBCs
- Elevated WBCs indicate infection, inflammation or contamination
- RBCs
- 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
- Persistent hematuria always warrants further work-up
- 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
- 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
- Crystals
- May be normal
- Calcium oxalate crystals - ethylene glycol ingestion
- Uric acid crystals - tumor lysis syndrome, gout
- Cystine crystals - cystinuria
- Magnesium ammonium phosphate and triple phosphate crystals - UTI caused by Proteus, Klebsiella
- 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
- ↑ 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.