Physical Examination of Urine

• Clinical Microscopy


  Examination of urine to provide preliminary information concerning disorders of the urinary tract and even disorders of the other systems of the body as well as genetic abnormalities
• Physical examination of urine

  Confirms or explains the findings in the chemical and microscopic exam aspects of a routine urinalysis
• Observation of the physical characteristics of urine provides preliminary information concerning disorders of the urinary tract and even disorders of the other systems of the body as well as genetic abnormalities
• Physical properties of urine

  • Color
  • Clarity
  • Specific Gravity
  • Odor
  • Volume
• Odor and urine volume are not routinely assessed and therefore are not part of the documentation process
• Urine color


  Variations can be explained by a person's metabolic function, physical activity, diet, medication intake and pathologic conditions
• Assessment of urine color is subjective, oftentimes arbitrary
• Normal urine color


  A color spectrum from pale, almost colorless shades of yellow to amber (yellow-orange)
• Urochrome


  Pigment that causes the yellow hue of urine, a product of endogenous metabolism
• The intensity of the yellow color in a fresh specimen can give a rough estimate of urine concentration
• Not all yellow-colored urine are "normal" or come from healthy individuals
• Uroerythrin


  Pink pigment that is most evident in specimens that have been refrigerated, resulting in the precipitation of amorphous urates crystals, which uroerythrin attaches to and gives a pink color to the sediment
• Urobilin


  Oxidation product of urobilinogen, a normal urinary constituent in small amounts, imparts an orange-brown color to urine that is not fresh
• Formation of urobilinogen


  RBCs are replaced in the body, lysed in organs like the spleen, broken down into unconjugated bilirubin, transported to the liver, conjugated, travels to the intestines and converted by bacteria into urobilinogen, some gets reabsorbed by the liver and kidneys into the urine
• Large amounts of urobilinogen in the urine indicate a pathologic disease; urobilin in urine appears when specimens are not processed and urobilinogen is oxidized
• Different urine colors can affect the interpretation of other tests, most often in the chemical examination of urine using reagent strips because these tests are based on reactions that are visualized as color changes
• Dark yellow / brown / orange urine

  Often signifies normal albeit concentrated urine, can also be due to the presence of bilirubin in the urine which is abnormal and pathologic
• Bilirubin in urine


  Detected using reagent strip test and ictotest tablets, photo-oxidized to biliverdin will have a more yellow-green color than orange or dark-yellow
• Dark yellow urine


  Can be seen when large amounts of urobilinogen are photo-oxidized into urobilin, foam is not seen when shaken in this case
• Medications causing yellow-orange urine

  Phenazopyridine and azo-gantrisin compounds, specimens containing phenazopyridine also produce a yellow foam when shaken
• Red / pink / brown urine

  Often indicates the presence of blood, the amount of blood, the urine pH and the length of time the blood has remained in the urine can influence the color shades and intensity
• Hematuria


  Blood in the urine, often pathologic in nature, originating from anywhere along the urinary tract
• Hemoglobinuria and myoglobinuria


  Presence of hemoglobin and myoglobin in urine respectively, hemoglobinuria is commonly due to the destruction of red blood cells within the blood vessels, myoglobinuria can occur when there is a significant breakdown of skeletal muscle
• Hematuria vs hemoglobinuria/myoglobinuria


  Hematuria is cloudy due to the presence of intact, unlysed RBCs while hemoglobinuria/myoglobinuria is clear because there are no intact and unlysed RBCs
• Reagent strip test for red urine

  Freckled spots appear on the reagent test pads due to RBCs just being lysed at that exact moment
• Porphyrias


  Urine specimens containing porphyrins may be colored red (characteristically described as portwine) because of the oxidation of porphobilinogen to porphyrins
• Dark brown / black urine

  May contain melanin and homogentisic acid, melanin is an oxidation product of the colorless pigment melanogen produced in large amounts in cases of melanoma, homogentisic acid is a metabolite of phenylalanine that imparts a black color to alkaline urine in persons with alkaptonuria
• Medications causing brown/black urine

  Levodopa, methyldopa, phenol derivatives and metronidazole
• Blue / green urine

  Pathologic causes are limited to bacterial infections (urinary tract infections) caused by Pseudomonas species, due to the pigments pyocyanin and pyoverdin
• Medications causing blue urine

  Methocarbamol, methylene blue and amitriptyline
• Urine clarity


  Refers to the transparency or turbidity of a urine specimen, common terminology includes clear, hazy, cloudy, turbid, milky
• Freshly voided urine from normal, healthy persons are usually clear, especially if it is a midstream clean-catch specimen
• Non-pathologic causes of urine turbidity

  • Normal crystals
  • Radiographic contrast media
  • Mucus
  • Squamous epithelial cells
  • Spermatozoa
  • Prostatic fluid
  • Fecal contamination
  • Talc
• Pathologic causes of urine turbidity

  • RBC
  • WBC
  • Bacteria
  • Yeast
  • Renal epithelial cells
  • Fat
  • Abnormal crystal
  • Calculi
  • Pus
• Renal tubular cells


  The cytoplasm is not abundant and the nuclei are enlarged and they are seen in clusters
• We cannot establish the cause of urine turbidity unless we can examine the chemical and microscopic aspects of urinalysis
• Specific gravity


  The density of a solution compared with the density of a similar volume of distilled water at a similar temperature, provides a measurement of the concentrating abilities of the kidneys which are often the first to be impaired in renal disease
• The kidneys function to filter blood (plasma), reabsorb and secret various substances, with reabsorption occurring in the tubules and collecting ducts (water)
• Urine turbidity cannot be established without examining the chemical and microscopic aspects of urinalysis
• Specific gravity


  The density of a solution compared with the density of a similar volume of distilled water at a similar temperature