Urinalysis

URINALYSIS OVERVIEW

  • Urine is a waste product consisting primarily of urea and other substances eliminated from the bloodstream by kidneys.
  • Urinalysis serves as a critical tool in in vitro diagnostics, allowing for over 100 different tests to be performed on urine samples.
  • Urinalysis generally encompasses three main components:
    • Physical Examination: Involves assessing urine color, clarity, and odor.
    • Chemical Examination: Involves quantitative tests using reagent strips or other technologies to measure compounds.
    • Microscopic Examination: Involves centrifuging urine to observe sediment under a microscope.

TESTS AND READING TIME

  • General testing parameters include:
    • Leukocytes (LEU)
    • Negative: Suggests absence of infection.
    • Nitrite (NIT)
    • Negative: Indicates no bacterial infection, especially if Gram-negative.
    • Protein (PRO)
    • Variants ranged from negative to 2000 mg/dL indicating severe presence (++++).
    • Specific Gravity (SG)
    • Normal range: 1.005 to 1.030, indicating kidney concentrating ability and hydration level.
    • pH
    • Normal: 4.6 to 8.0, indicating acidity or alkalinity.
    • Ketone (KET)
    • Ranges from negative to large (80+ mg/dL), indicating metabolic states.
    • Bilirubin (BIL)
    • Normal is negative, presence indicates liver dysfunction or bile obstruction.
    • Glucose (GLU)
    • Normal level is negligible; presence suggests diabetes or high sugar consumption.

SUBJECTIVE TESTS FOR URINE

  • Color: Influenced by hydration levels, diet, medications, and disease states.

    • Dark urine: Indicates dehydration.
    • Bright yellow from Vitamin B supplements.
    • Red-brown from: blood, blackberries, beets, or some medications.
    • Green from: asparagus consumption.

  • Clarity: Urine should be clear; turbidity suggests possible infections, crystals, or blood presence.

  • Odor: Typical is slightly "nutty". Changes can signal disease presence:

    • Bad odor: UTI or E. coli infection.
    • Sweet, fruity odor: Common in uncontrolled diabetes or during periods of starvation.

SPECIFIC GRAVITY

  • Normal range is 1.005-1.030; an important measure of urine concentration:
    • Low SG: Indicated by high fluid intake, leading to more dilute urine.
    • High SG: Indicated by dehydration or the inability to concentrate urine, potentially signaling hormonal imbalances or renal issues.

pH AND PROTEIN

  • pH: Indicates acidity vs basicity:

    • Normal range: 4.6 to 8.0.
    • Abnormal values may indicate diet or infections (4 is very strong acid, 7 is neutral, 9 is strong base).

  • Protein: Typically absent in urine; presence indicates renal dysfunction, caused by:

    • Infections, strenuous exercise, kidney damage, or conditions such as preeclampsia during pregnancy.

GLUCOSE IN URINE

  • Glucose should not be present in urine:
    • Presence indicates high blood sugar, often seen in uncontrolled diabetes or from consuming large amounts of sugar or glucose I.V.
    • Random urine sample with glucose warrants further investigation for diabetes.

NITRITES IN URINE

  • Nitrates usually excreted converted to nitrites by bacteria:
    • Presence typically indicates a urinary tract infection (UTI).
    • E. coli and similar Gram-negative bacteria are commonly involved.
    • Some UTIs might not have nitrites, especially if caused by Gram-positive bacteria.

PHOSPHATES AND ESTERASE

  • Phosphates: High urine levels indicate potential kidney issues or high dietary phosphorus intake.

  • Leukocyte Esterase: Indicates presence of leukocytes in urine:

    • Suggests possible UTI.

KETONES IN URINE

  • Ketones result from fat/protein metabolism; normally undetectable:
    • Large amounts indicate diets like ketoacidosis or metabolic abnormalities.
    • Some dietary monitors track moderate ketone levels to help manage progress.
    • Starvation or severe vomiting may also trigger ketone presence.

BILIRUBIN IN URINE

  • Bilirubin, a breakdown product of red blood cells, should not be present in urine:
    • Presence suggests potential liver damage or bile flow obstruction.

UROCHROME

  • Urochrome: A breakdown product of bilirubin that imparts yellow color to concentrated urine, often seen in dehydration.

MICROSCOPIC ANALYSIS

  • Under microscopy, urine sediment can reveal:
    • Red/White Blood Cells:
    • Normally absent; presence may indicate inflammation or kidney injury.
    • Physical trauma or strain (e.g., marathon running) can also result in blood presence.
    • Casts:
    • May form in renal tubules, giving insights into kidney disease types (red/white blood cells, waxy, or fatty casts).
    • Crystals:
    • Healthy individuals may have a few, but an abundance may indicate kidney stones or metabolism issues.

LAB PROCEDURES AND CLEANUP

  • Complete the Urinalysis Mystery Sheets as part of coursework.
  • Laboratory cleanliness is essential; trays must be cleaned thoroughly before departure.