QS Study

Characteristics of Normal Urine

Urine is a fluid by-product of the body concealed by the kidneys through a procedure called urination. It is an aqueous solution of greater than 95% water. Other constituents include urea, chloride, sodium, potassium, and other dissolved ions, and inorganic and organic compounds. Visual observation of a urine test can give vital clues as to indication of pathology. The color of normal urine is regularly light yellow to amber.

Physical characteristics – The physical characteristics of urine include observations and measurements of color, turbidity, odor, specific gravity, pH, and volume.

  • Volume → 0.5 – 2L (Average – 1.5L/day)
  • Colour → Straw (due to urochrome)
  • Specific gravity → 1.015 – 1.035
  • Osmolarity → Normally hypertonic 500 – 600 mos m/L.
  • Appearance → clear
  • Smell → NH3 smell

Chemical characteristics: The normal chemical composition of urine is mostly water substance, but it also includes nitrogenous molecules, such as urea, as well as creatinine and other metabolic waste components.

pH: Normally acidic [pH = 4.5 – 6.8]

Organic substance –

(a) Protein – normally no protein (< 30 mg/day)

(b) Urinary nitrogenous substances. (<14 gm /day) Urea, Uric acid, Creatinine, NH4+.

Inorganic Substance –

(a) Cation: Na+, K+, Ca++, Mg++

(b) Anion: Cl, SO4, PO4.

Microscopic findings

  • Epithelial cells – 1-10/ HPF.
  • Pus cells – 0-3/HPF.

Others features

  • Glucose → Absent
  • Ketone body → Absent
  • Bilirubin → Absent
  • Bile salt → Absent
  • Blood → Absent
  • Urobilinogen → A small amount.