Urinalysis

From Anvita Health Wiki

Contents 1 More Specific Terms 2 Introduction 3 Indications 4 Reference-interval 5 More General Terms 6 Additional Terms 7 References

More Specific Terms

• amorphous crystals in urine
• amorphous sediment in urine
• bacteria in urine
• crystals in urine
• eosinophils in urine
• leukocytes in urine
• mucus in urine
• spermatozoa in urine
• tubular cells in urine
• urinary cast
• urinary indices
• urine dipstick
• urine microscopy

Introduction

• Also see:

• urine dipstick (1st step in urinalysis)
• 24 hour urine

Indications

• evaluation of urologic disease

• urinary tract infection
• proteinuria
• glucosuria
• ketonuria
• hematuria
• crystalluria

Reference-interval

• 
  

• Microscopy:

• WBC:

• > 5 WBC/ hpf in spun urine is considered abnormal
• associated with infections or allergic reactions 2 RBC: > 3 RBC/ hpf is considered abnormal; dysmorphic RBC (> 80%) indicate glomerular disease

• Eosinophils: Hansen's stain - interstitial nephritis
• Bacteria:

• >1 bacteria/ hpf (oil) in unspun urine, or
• >10 bacteria/ hpf (oil) in centrifuged urine correlates with >10E5 colony forming units per mL on culture

• tubular epithelial cells

• acute tubular necrosis ( ATN)
• acute interstitial nephritis ( AIN)

• crystals

• calcium oxalate
• struvite ( magnesium ammonium phosphate in basic pH often secondary to urea-splitting organism)

• casts:

• casts are cylindrical aggregates of uromodulin ( Tamm-Horsfall glycoprotein) that trap WBC, RBC or non- cellular material within their lumen
• WBC casts are suggestive of interstitial nephritis
• RBC casts are suggestive of glomerulonephritis or vasculitis
• broad, muddy brown casts are associated with acute tubular necrosis ( ATN)
• hyaline casts: uromodulin alone (benign)

• maltese cross:

• lipid droplets seen in polarized light suggest nephrotic syndrome or lipid-storage disease
• lipids may appear as droplets, oval fat bodies or fatty casts
  

• urine pH:

• normal 4-7.5
• diurnal variation
• pH > 7 suggests infection with urea-splitting organisms
• pH < 5.5 excludes RTA type I
• acidic aurine

• high protein diet
• acidosis
• K+ depletion

• alkaline urine

• vegetarian diet
• alkalosis (unless K+ depleted)
• urease-producing bacteria
  

• specific gravity: 1.005-1.031 (50 - 1400 mOsm/kg)
  
• appearance:

• turbid: phosphate, urate, RBC, WBC
• foam: protein (white), bilirubin (yellow)
• white: chile, phosphate, pus, elephantiasis
• yellow: urochrome
• blue green: methylene blue, Pseudomonas
• orange-red: bile, beets, pyridium, rifampin
• red-brown: hemoglobin, myoglobin, levodopa
• yellow which turn red: PAS
  

• protein:

• normal < 150 mg/day
• most renal parenchymal disease will manifest some degree of proteinuria
• tubular proteinuria rarely > 2 g/day
• nephrotic syndrome > 3.5 g/day
• test

• colorimetric "stix"

• false positives may occur with:

• benzalkonium, chlorhexidine

• false negatives may occur with immunoglobulin light chains ( Bence-Jones protein)
• trace to 1+ protein rarely significant

• precipitation: sulfosalicylic acid
• dye-binding: Coomassie brilliant blue
• chemical

• Biuret
• Folin - Lowry

• protein electrophoresis

• urine protein/creatinine ratio

• a value 0.1 generally corresponds to 24 hour urine protein of < 100 mg/day
  

• glucose:

• glucosuria in the absence of hyperglycemia suggests proximal tubule dysfunction

More General Terms

• clinical laboratory test

Additional Terms

• causes of urine discoloration
• proteinuria
• urinary cast
• urine chemistry test
• urine culture

References

1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 620
2. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, American College of Physicians, Philadelphia 1998, 2006
3. Simerville JA, Maxted WC, Pahira JJ. Urinalysis: a comprehensive review. Am Fam Physician. 2005 Mar 15;71(6):1153-62. Review. PMID: [1]
4. WebPath: Urinalysis [2]

urinalysis (UA)