UA Diagnostics Flashcards
When would you order a UA
- Flank pain, back pain, abdominal pain, painful or frequent urination, changes in urine color (blood)
- Part of wellness exam, new pregnancy evaluation
Purpose of the UA
Detect:
- substances secreted in the urine reflecting metabolic disturbances
- ->Ex: glucose, nitrite, ketones
- Intrinsic renal conditions
- ->Ex: acute or chronic kidney dz, other dx’s resulting in the failure of the kidney to maintain homeostasis of body fluid volume and composition
Types of Urine Specimens
- Random
- Catheter
- Midstream clean-catch
- First morning
- Fasting
- 2 hour post prandial
- Suprapubic puncture
- Pediatric bags
Three components of UA
- Physical: color, transparency, odor, volume
- Chemical: protein, glucose, ketone, bilirubin, pH, blood, nitrite, leukocyte esterase, urobilinogen, specific gravity
- Microscopic (“formed elements”): WBC’s, RBCs, epithelial cells, casts, crystals, microorganisms
How is a UA ordered?
- Dipstick UA: typical UA point of care diagnostic test
- Dipstick UA w/micro if indicated
- Complete UA (includes micro)
- Complete UA with relax urine culture: UA, micro eval, and culture
Colored Urine Specimen and what it means
Straw: normal
Red: blood in the urine
Amber: Dehydrated
Turbid Urine Specimens
=Cloudy samples
–>Cells, infection
Reagent Strip/Dipstick Analysis
- Convenient and easy to use
- Requires strict compliance w/ directions to ensure analytical reliability
- DO NOT store in a refrigerator
- Avoid exposing reagent strips to moisture, fluorescence light, sunlight, heat, acids, alkalis,
- Do not touch test areas of reagent strip
Leukocyte esterase
- WBC’s in the urine
- ->this is a marker for WBC’s
Nitrites
- Most specific test on dipstick to identify infection!
- Convert nitrates to nitrites by bacteria (gram -)
Most common cause of UTI’s
E. coli
Urobilinogen
- RBC breakdown
- Indicative of hemolysis, bilirubin process
Protein
- Reabsorption should be 100% by the kidneys, thus there should be NO protein in the urine (a.k.a Albumin)
- Filtering process in the kidney is breaking down= DM, HTN that lead to nephropathy/chronic kidney dz (CKD)
pH
-Helps you assess if acidic or alkalotic
Blood
- Should be no blood in the urine
- Kidney stones: nephrolithiasis
- Menstruation: contaminated sample
- Note: not actually detecting RBC’s
- ->enzymatic rxn when RBC’s are present in the urine
Specific gravity
- Concentration of pt’s urine low= hydrated
- Concentration high=Dehydrated
Ketones
-Metabolite of fat breakdown in the body
Causes: dietary changes, persistent N/V (body starts to breakdown fat for energy source)
-DKA!!! uncontrolled diabetes, hyperglycemia
Bilirubin
-Part of physiological process of bilirubin breakdown
Glucose
Approximately 250, patient starts spilling over glucose into urine (DM)
Microscopic exam of the. urine sediment used to identify:
- Cells
- Casts
- Crystals
What are the associated conditions with RBC?
- Acute Kidney Injury (AKI)
- Ureterolithiasis
- neoplasm
- Infection
WBC
- Infection
- Renal inflammatory process: interstitial nephritis
Renal epithelial
AKI: acute tubular necrosis, interstitial nephritis, nephritic syndrome
Squamous epithelial
Contamination!!
Oval fat bodies
Nonspecific, nephrotic syndrome
Urinary Casts
- Urinary protein forms fibrils that attach to the epithelial cells lining the tubule lumen as:
- ->Urine tubules become very concentrated
- ->Urine flow ceases (stasis occurs)
- ->Urinary pH is very low
- ->Urinary salt concentration is high
-Fibrils may intertwine to form cast–> Casts may entrap chemicals or formed elements that are present in the urine–>casts are eventually washed out of their point of origin and appear in. urine
Tamm-Horsfall Glycoprotein
- Major protein constituent of normal urine (and often forms the common matrix of casts)
- Major defense protein of urothelium against bacteria
- Reagant chemical strips DO NOT detect this protein b/c so heavily glycosylated
Common Urinary Casts
- Hyaline
- WBC
- RBC
- Granular
- Renal tubular epithelial cell
- Waxy
- Broad
Associated condition with Hyaline casts
Nonspecific, may be normal
RBC
AKI (glomerulonephritis), nephritic syndrome
WBC
Infection (pyelonephritis), AKI/renal inflammatory process
Epithelial
AKI (acute tubular necrosis interstitial nephritis), nephritic syndrome
Granular (“muddy brown”)
AKI. (acute tubular necrosis)
Waxy
Nonspecific; chronic renal dz
Broad
Chronic renal dz
Abnormal Urinary Crystals
-Typically found @ acidic urinary pH
Causes: Abx, amino acids, altered metabolism (bilirubin, cholesterol)
