Urinalysis Overview

Urine Analysis Overview

• Urinalysis involves chemical and microscopic tests to detect products of normal and abnormal metabolism, cells, and bacteria in urine.
• Urine is the filtered product of the urinary system.
• Microscopically, microbiologically, chemically, and immunologically, urine reflects the state of the urinary system's normality or abnormality.
• Urinalysis is categorized into two main groups: routine and specific urinalysis.

Routine urinalysis consists of:

• General Urine Examination (GUE) which includes:
  • Physical appearance examination (volume, color, odor, reaction (pH), specific gravity)
  • Chemical composition examination (proteins, sugars, ketone bodies, bile salts, bile pigments, blood)
  • Microscopic composition examination (cells, crystals, casts, microorganisms, parasites, contamination)

Specific urinalysis includes:

• Urine culture: detects the presence of bacteria
• Microbial sensitivity test: determines specific bacteria sensitivity to antibiotics
• Immunological tests: identify specific immune factors

Physical Appearance of Urine

• Normal urine is pale yellow to amber, clear to slightly hazy, with a pH range of 4.5-8.0.
• Urine appearance can change due to various abnormalities:
  • Cloudy urine, often with an unpleasant odor, containing white blood cells (WBCs), may indicate a bacterial infection.
  • Red or cloudy urine due to red blood cells (RBCs) can result from urinary shistosomiasis or bacterial infection.
  • Brown or cloudy urine due to hemoglobin can indicate blackwater fever or other conditions causing intravascular hemolysis.
  • Yellow-brown or green-brown urine (bilirubin) can suggest acute viral hepatitis or obstruction jaundice.
  • Urine that contains urobilin/oxidized urobilinogen can be due to haemolysis, or hepatic cellular jaundice
  • Milky white urine may contain chyle (fatty lymph) which is an indication of Bancroft filarial.

Urine pH

• Urine pH is not a reliable indicator of abnormalities on its own.
• Kidneys play a key role in maintaining acid-base balance and urine pH correlates with blood acidosis or alkalosis.
  • Increased protein intake leads to acidic urine.
  • Increased vegetable & citrus fruit intake can result in alkaline urine.

Specific gravity

• Specific gravity (SG) measures the concentration of dissolved substances in urine.
• Normal urine ranges from 1.010 to 1.025.
• High SG (above 1.025) indicates highly concentrated urine, which could be due to: diabetes mellitus, large amounts of medication, or radiological studies.
• Low SG (below 1.010) indicates low concentrated urine indicative of diabetes insipidus, renal failure, or polyuria.

Chemical and Biochemical Composition

• Reagent strips (dipsticks) are used for routine chemical tests using chemical reactions on the strip which cause a color change when contacted with urine.
• The color change is compared to a color chart to determine the amount of the specific substance in the urine sample
• Key tests identified include glucose, proteins, bilirubin, urobilinogen, ketones, blood, and uric acid.

Microscopic Examination of Urine

• Examine urine microscopically to identify solid components.
• Normal sediment can include white blood cells (WBCs), red blood cells (RBCs), casts, yeast cells, parasites, bacteria, epithelial cells, and spermatozoa.
• Increased WBCs suggest urinary tract infection or inflammation (pyuria).
• RBCs indicate potential kidney damage, urinary tract tumors or menstruation.
• Epithelial cells, if found in large quantities, could indicate urinary tract infection (UTI), inflammation in the urinary tract or kidney issues.
• Casts are formed from abnormal proteins and indicate kidney issues.
• The presence of yeast or parasites indicates infections.

Specific Substances in Urine

• Glucose: Excess glucose in urine typically indicates diabetes or conditions increasing blood glucose beyond the renal threshold.
• Proteins: High protein levels, particularly albumin, are indicative of kidney dysfunction.
• Bilirubin: Elevated bilirubin suggests liver issues (hepatitis, biliary obstruction).
• Urobilinogen: Increased urobilinogen indicates liver or prehepatic issues(jaundice).
• Ketones: High ketone levels can suggest problems like insulin deficiency or starvation.
• Blood: Presence of red blood cells (RBCs) can indicate damage to the kidney or urinary tract.
• Uric acid: High or low levels might indicate conditions like gout or metabolic issues.