Urine Analysis

Item Observations Significance of finding
Color Yellow Normal, due to urochrome or vitamin B6
  Red shades Erythrocytes, Hb, myoglobin, porphyrins, drugs, beets, red candy
  Green to yellow-brown Bile
  Brown to black Old blood, hemosiderin, myoglobin, melanin, certain laxatives
Turbidity Cloudy/Not clear Heavy conc of crystals, erythrocytes, bacterial infx, vaginal secretions, leukocytes
Odor Acetone Ketosis
  Maple syrup Maple syrup disease
  "Sweet" Asparagus

 

Item Normal Values Significance of abnormal values
Specific Gravity 1.010 - 1.025 High = dehydrated; Low = fluid overloaded
pH 4.5 - 8.0  
Protein 0  
Glucose 0  
Ketones 0
  • Ketoacidosis
  • Starvation
Hemoglobin/
Myoglobin		 0
  • Crushing injuries
  • Electrocution
  • Clostridium welchii (C. perferingens) infx
  • Necrosis of muscle
  • Strenuous exercise
  • Certain genetic defects

Prolonged, severe myoglobinuria is toxic to renal tubular cells -> failure
Bilirubin 0
  • Obstruction of the biliary system
  • Hepatocellular damage

Only water soluble bilirubin, conjugated to glucuronic acid, is excreted in urine.  Therefore, bilirubin is not found in hemolytic disease which increases un-conjugated bilirubin which is not excreted in urine.
Urobilinogen 0
  • Hemolytic anemia
  • Early parenchymal liver disease
Leukocyte Esterase 0 Bacterial infx
(from leukocytes in the urine that contain the enzyme esterase)
Nitrites 0 Bacterial infx
(from enterobacteriaceae that convert urine nitrates to nitrite)
Dip stick leukocyte esterase and nitrites 0

  • Sensitivity of 95 percent for UTI

  • Specificity of 75 percent for UTI

  • Positive predictive value is 30 to 40 percent (when tested in patients suspected of possible UTI)

  • Negative predictive value is 99 percent

Follow any positive dip stick with a lab UA, UCx and sensitivities

Pappas, PG.  "Laboratory in the diagnosis and management of urinary tract infections."  Med Clin North Am 1991 Mar;75(2):313-25
Bacteria 0 > 10,000 colony forming units/ml *
* (Several cases where this threshold may not be met)

 

Special Tests Metabolite Significance Normal

Pheochromocytoma
and
Neuroblastoma

 Vanillymandelic acid (VMA) in 24 h urine - Elevated in diseases
- No bananas, coffee, tea or certain drugs during and prior to test
- 90% have elevation in pheo.		 10-15 mg/day
Metanephrine assay
24 h urine		 - Elevated in diseases
- 98% have elevation in pheo.
- False positives in severe stress, shock, sepsis and metastatic dz.		 Up to 1 mg/day
Homovanillic acid (HVA) in 24 h urine If you suspect neuroblastoma  
Plasma catecholamines    
Pheochromocytoma Vanillymandelic acid (VMA) in 24 h urine Major metabolite elevated in pheo.
90% have elevation		 10-15 mg/day
Neuroblastoma Homovanillic acid (HVA) in 24 h urine Major metabolite elevated in neuroblastoma  

 

Casts Significance
Hyaline Associated with all renal diseases secondary to essential hypertension and nephrotic syndrome
White blood cell Associated with diseases with leukocyte exudation and interstitial inflammation (Pyelonephritis)
Red blood cell Indicates severe injury to the glomerular basement membrane.
Associated with:
  • Acute glomerulonephritis
  • Lupus nephrities
  • Goodpasture's syndrome
  • Subacute bacterial endocarditis
Renal epithelial Due to constant desquamation and renewal of the renal epithelium.
Presence points to a pathological process occurring in the kidney and affecting the tubular portion of the nephron (tubular damage).

Associated with exposure to nephrotoxic agents or viruses
Granular Formed from breakdown products of cellular casts and immunoglobulins
Waxy Result of progressive degenerative changes occuring in cellular casts.

Associated with severe chronic renal disease and amyloidosis
Fatty Due to leakage of lipoproteins through the glomerular filter.

Associated with nephrotic syndrome, diabetes mellitus and damaged renal tubular epithelial cells

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