Urinalysis

• URINE: 'Sterile liquid by-product derived from metabolic processes of the body and is secreted by the kidneys via a process that may be called micturition, urination or voiding.'
• Urine refers to an ultrafiltrate containing waste products excreted by the kidneys, temporarily stored in the urinary bladder and excreted through the urethra.
• Urine is a liquid tissue biopsy of the urinary tract.
• Urine is continuously formed by the kidneys in varying amounts depending on physical activity, the time of day, and the activity of hormones such as ADH.
• Urine Composition


  • Composed of 95% water and 5% solutes
  • Consists of urea and other organic and inorganic chemicals dissolved in water
  • Total solids (TS) in 24 hours = 60 grams (35g organic & 25g inorganic)
  • Major components include UREA, CHLORIDE, and other substances like Hormones, Vitamins, Medications, Formed Elements
• Urea


  Major organic dissolved solid in the urine, a metabolic waste product produced in the liver from the breakdown of protein and amino acids
• Chloride


  Major inorganic dissolved solid in the urine, followed by Na and K
• Other Substances Found in Urine

  • Hormones
  • Vitamins
  • Medications
  • Formed Elements (Cells, Casts, Crystals, Mucus, Bacteria)
• Normal urine volume ranges from 600-2000mL/day, with an average of 1200-1500mL/day
• Night:Day ratio of urine output is 1:2 to 1:3, with mornings having twice/thrice daily output compared to night
• Factors that influence urine volume

  Fluid intake, Fluid loss from nonrenal sources, Variations in the secretion of antidiuretic hormone
• Polyuria is an increase in daily urine volume, often associated with Diabetes Mellitus and Diabetes Insipidus
• Polyuria may be artificially induced by diuresis, diuretic medication, diuretic drinks, nervousness, and diabetes mellitus
• In Diabetes Mellitus, polyuria is present due to high solute (glucose) concentration leading to excessive urination volume
• In Diabetes Insipidus, the problem lies in the hormone ADH, leading to excessive water excretion through urine
• Diabetes insipidus is a condition related to decreased or defective ADH, leading to excessive water excretion through urine
• ADH


  Hormone responsible for water reabsorption
• Polydipsia and polyuria are signs of diabetes insipidus
• The secretion of ADH is increased at night, leading to water retention and possible edema or swelling
• Diabetes mellitus insipidus is characterized by defects in insulin production, increased glucose concentration, and decreased or defective ADH
• Signs of diabetes mellitus insipidus

  • Polyuria
  • High SG
• Oliguria


  Decreased urine output
• Oliguria levels


  • Adults: ≤400mL/day
  • Infants: ≤1ml/kg/hr
  • Children: ≤0.5mL/kg/hr
• Oliguria is commonly seen in dehydration due to excessive water loss
• Anuria


  Cessation of urine flow
• Anuria may result from complete obstruction or toxic agents
• Nocturia


  Increased nocturnal excretion of urine with specific gravity of <1.018 at night
• Nocturia associations


  • Normal day to night urine ratio - 2:1 to 3:1
  • Increased in pregnancy
  • Associated with chronic progressive renal failure
• Dysuria


  Painful urination
• Urinalysis


  Examination of urine for diagnostic purposes, aiding in disease treatment monitoring
• Urine contains most of the body's waste products
• Urine chemical changes are directly related to pathologic conditions
• History of Urinalysis dates back to 5th Century BC with Hippocrates writing about "uroscopy"
• Color charts describing the significance of different urine colors were developed in 1140 AD
• Thomas Bryant published a book in 1627 about the credibility of urinalysis being compromised by charlatans
• Frederik Dekker discovered "albuminuria" in 1694 by boiling urine
• The invention of the microscope in the 17th Century led to the examination of urinary sediment
• Richard Bright introduced the concept of urinalysis as part of a doctor's routine patient examination in 1827
• In the 1930s, urinalysis tests became impractical, leading to its disappearance from routine examinations
• In the 1950s, chemically impregnated strips were developed for urinalysis