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urinalysis (UA)

Also see: 1) urine dipstick (1st step in urinalysis) 2) 24 hour urine Indications: - evaluation of urologic disease - urinary tract infection - proteinuria - glucosuria - ketonuria - hematuria - crystalluria - pregnancy [2] - before & after invasive urologic procedure [2] Contraindications: - routine health surveillance in asymptomatic patients [2] - routine preprocedural urinalysis [4] - screening for urothelial cancer [2] Reference interval: Microscopy: 1) WBC: a) > 5 WBC/hpf in spun urine is considered abnormal b) associated with infections or allergic reactions 2 RBC: > 3 RBC/hpf is considered abnormal; dysmorphic RBC (> 80%) indicate glomerular disease 3) Eosinophils: Hansen's stain - interstitial nephritis 4) Bacteria: a) >1 bacteria/ hpf (oil) in unspun urine, or b) >10 bacteria/hpf (oil) in centrifuged urine correlates with >10E5 colony forming units per mL on culture 5) tubular epithelial cells a) acute tubular necrosis (ATN) b) acute interstitial nephritis (AIN) c) heavy metal poisoning [6] 6) squamous epithelial cells - common in voided or catheterized samples due to urethral or vaginal contamination 7) crystals a) calcium oxalate b) struvite (magnesium ammonium phosphate in basic pH often secondary to urea-splitting organism) c) uric acid crystals d) calcium phosphate crystals e) tyrosine crystals are associated with liver disease - leucine crystals may occur with tyrosine crystals [6] 8) casts: a) casts are cylindrical aggregates of uromodulin (Tamm-Horsfall glycoprotein) that trap WBC, RBC or non-cellular material within their lumen b) WBC casts are suggestive of interstitial nephritis c) RBC casts or urine acanthocytes are suggestive of glomerulonephritis or vasculitis d) broad, muddy brown casts are associated with acute tubular necrosis (ATN) e) hyaline casts: uromodulin alone (benign) 9) maltese cross: a) lipid droplets seen in polarized light suggest nephrotic syndrome or lipid-storage disease b) lipids may appear as droplets, oval fat bodies or fatty casts urine pH: 1) normal 4-7.5, 5.0-6.5 [2] 2) diurnal variation 3) pH > 7 suggests infection with urea-splitting organisms 4) pH < 5.5 excludes RTA type I 5) acidic urine a) high protein diet b) acidosis c) K+ depletion 6) alkaline urine a) vegetarian diet (low acid ingestion) b) alkalosis (unless K+ depleted) c) urease-producing bacteria d) postprandial alkaline tide e) renal tubular acidosis specific gravity: - reference inerval: 1.005-1.031 (50 - 1400 mOsm/kg) - low with dilute urine - high with concentrated urine, glycosuria or contrast agent appearance: 1) turbid: phosphate, urate, RBC, WBC 2) foam: protein (white), bilirubin (yellow) 3) white: chile, phosphate, pus, elephantiasis 4) yellow: urochrome 5) blue green: methylene blue, Pseudomonas 6) orange-red: bile, beets, pyridium, rifampin 7) red-brown: hemoglobin, myoglobin, levodopa 8) yellow which turn red: PAS protein: 1) normal < 150 mg/day 2) most renal parenchymal disease will manifest some degree of proteinuria 3) tubular proteinuria rarely > 2 g/day 4) nephrotic syndrome > 3.5 g/day 5) test a) colorimetric "stix" 1] false positives may occur with: - benzalkonium, chlorhexidine 2] false negatives may occur with immunoglobulin light chains (Bence-Jones protein) 3] trace to 1+ protein rarely significant b) precipitation: sulfosalicylic acid c) dye-binding: Coomassie brilliant blue d) chemical - Biuret - Folin - Lowry e) protein electrophoresis 6) 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

Related

urine chemistry test urine culture urine discoloration

Specific

urine dipstick urine microscopy

General

clinical laboratory test

Properties

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) 11,14,17,18,19. American College of Physicians, Philadelphia 1998,2006,2015,2018,2021. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  3. Simerville JA, Maxted WC, Pahira JJ. Urinalysis: a comprehensive review. Am Fam Physician. 2005 Mar 15;71(6):1153-62. Review. PMID: 15791892
  4. Shenoy ES, Giuriato MA, Song Z et al. Prevalence, costs, and consequences of low-value preprocedural urinalyses in the US. JAMA Intern Med 2021 Aug 2; [e-pub]. PMID: 34338720 PMCID: PMC8329792 (available on 2022-08-02) https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2782461
  5. WebPath: Urinalysis http://library.med.utah.edu/WebPath/TUTORIAL/URINE/URINE.html
  6. Medscape: Urinalysis: Urinalysis: 5 Question Quiz https://reference.medscape.com/viewarticle/993977

Component-of

hypertension panel

Components

amorphous sediment in urine appearance of urine cells in urine character of urine clarity of urine collection duration of urine crystals in urine mucus in urine protein in urine specific gravity of urine urinary cast urinary indices urine color