Urinalysis

Urine sample Acquisitions

-Midstream "Clean Catch": Sterile container; sterile wipes

-Catheter Acquisition: Indwelling-Foley; One time sampling

Colony forming units

-Usually only indicative for a concern when it reaches past 10^5

-Seen in Pylonephritis

Dipstick Colors for UA

-The darker the color, the more saturated that variable is in the urine

Yellow Urine Colors

Pale: Volume replete, hydrated

Dark: volume depleted, hyperbilirubinemia

Gross Hematuria

-Red Color

-Red Sediment

Hemoglobinuria & Myoglobinuria

-Red color

-Red Supernatant

Diet Related Red Urine

Beets, Rhubarb, blackberries

Orange colored Urine causes

Medication-induced:

Rifampin, Azo (UTI; bladder numbing)

Blue-Green Urine

-P. Aeruginosa UTI

Cloudy/turbid urine

pyuria - infection

Foamy/Frothy Urine

proteinuria

Specific Gravity (Dipstick UA)

how concentrated are solutes in the urine compared to water

-Density of urine relative to water

-Normal: 1.009-1.030

Presence of urinary glucose, protein, or RBC's invalidate test and urine osmolality must be used

Urine Osmolality (Lab)

-Concentration of particles per kilogram of solution

-Normal: 50-1200

Dilute Urine (specific Gravity & Osmolality)

-Low for both

Concentrated Urine (Gravity & OSmolality)

-High SG or osmolality

Arginine Vasopressin (AVP) and SG/Osmalality

AKA antidiuretic hormone (ADH)

Act on renal tubules to increase water retention → increases concentration of urine

(less water to particle ratio)

Diabetes Insipidus: SG/OSmolality

-Central: Inadequate AVP production

-Nephrogenic: Impaired AVP action on kidney

Cx: Polyuria, Polydipsia, large urine volumes; hypernatremia; Low Urine gravity

(you have no ADH. body can not reabsorb the water it is losing to urine. low urine gravity. lots of water, not a lot of stuff)

Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

-Excessive production of AVP: Neoplasms; CNS disorders, medications, or infections

-CX manifestations: H/A, confusion, N/V, Coma; Hyponatremia; Elevated Urine gravity

(body make too much ADH. very high SG. not much water in urine)

Acidotic Urine

pH <5

-Common causes: Metabolic acidosis

Alkalotic Urine

pH >7

Common causes: metabolic alkalosis. Infection with urea causing pathogen (Proteus spp); Standing urine samples

Urine Bilirubin

Total: direct and indirect

-Either Direct (Conjugated) or indirect (unconjugated)

Indirect/Unconjugated: bound to albumin and is NOT filtered by the kidney (bilirubin in urine can only be conjugated)

Direct/Conjugated: filtered but most is reabsorbed within proximal tubules

bilirubin presence is indicative of Hepatocellular disease

-May occur with jaundice

Urobilinogen

-Conjugated bilirubin is broken down by Gut Bacteria and leads to formation and absorption of urobilinogen

-Most is excreted by the liver

-Small amounts are excreted by the kidneys (should be very small amount in urine)

-In Liver failure: liver will be unable to clear this → increased levels of Urinary excretion

Gross or Microscopic Findings: Hematuria

loss of RBC in urine

(+) Heme

(+) Microscopic RBC's

Gross/Micro Findings: Hemoglobinuria (Hemolysis) or Myoglobinuria (Rhabdo)

(+) Heme

(-) Microscopic RBC's

Obstructive Jaundice UA

cannot pass bile into GI tract

Color: dark yellow (pigment of conjugated bilirubin)

Bilirubin: positive

Urobilinogen: depends on how much it is obstructed. less ub, more obstructed.

Blood: negative

Hemolysis

Color: red

Bilirubin: negative

Urobilinogen: positive

Microscopy: no RBC

Urine Protein

Protein: too large to fit through glomeruli and should not be present in urine

Dip-sticks are usually insensitive to non-albumin substances

Dipsticks measure as +1, 2+, 3+, 4+

-Used as a screening tool for Renal Disease

Urine Glucose + associated diseases

Continuously filtered by glomeruli and reabsorbed within the renal tubules

Glucosuria occurs when Renal threshold for this reabsorption is exceeded (>180 mg/dL)

Associated: Diabetes Mellitus; Medications (SGLT2 Inhibitors increase urinary output of this)

Urine Ketones + associated with

Ketones: byproduct of fatty acid break down (Lipolysis)

-Should NOT be present in Urine

Associated with: uncontrolled DM; Diet; Starvation

-Associated with metabolic acidosis

Urine Nitrite

Nitrites: byproduct of Gram (-) species metabolism

Agents: E. Coli and other enterobacteriaecae (Klebsiella & Proteus)

-usually NOT produced by Gram (+) organisms

Leukocyte Esterase

-Enzyme within WBC's

-Will be + with infection or inflammation

Acute Tubular Necrosis causes/signs

-Renal Tubular Damage results in AKI

-Causes: Ischemia, Nephrotoxins, Sepsis

-Signs: AKI + Reduced Urine Output

Glomerulonephritis causes/signs

-Inflammation of the Renal Glomeruli

-Causes: Autoimmune Process, Infection Related (Group A Strep)

-Signs: Hematuria, AKI, Edema, Proteinuria, HTN

Nephrotic Disease causes/signs

-Glomerular disease which result in alterations of basement membrane permeability

-Causes: Diabetes Mellitus, Amyloidosis

-Signs: Proteinuria (>3 g/24 Hours); Hypoalbumemia, Edema, HLD

Hyaline Casts

-Faint, colorless

-Concentration of mucoproteins secreted from renal tubules

-Non-specific; can be normal

Granular Casts

-Broad, fine or coarse

-Degraded cell products and serum proteins

indicative of Renal Parenchymal Disease; ATN (acute tubular necrosis)

Renal Tubular Epithelial Cell Casts

-Collection of Renal tubular epithelial cells

-Associated with ATN

Fatty Casts

-Hyaline casts which contain lipid droplets and can be overserved in pts with lipuria

-Associated with Nephrotic syndromes

Red Blood Cell Casts

-Collection of RBCs which have leaked into renal tubules through damage of glomerular basement membrane

-Occurs in Glomerularnephritis

White Blood Cell Casts

-Collection of WBCs which leaked into renal tubules

-Typically occur in upper urinary tract infections (Pyelonephritis)

Calcium Oxalate Crystals

-Small square crystals with Central cross

MC stone type

Uric Acid Crystals

-Rhomboids, Hexagons, or Squares

-Acidic Urine (Gout)

Struvite Stone (Triple Phosphate)

-"Coffin-Lids"

-Alkaline urine (Proteus infections)

Cystine Crystals

-Colorless hexagons

-Seen in patients with Cystinuria

Pathologies for 24 hour urine collection

-Calcium

increased: hyperparathryroidism, sarcoidosis, hyperthryoidism

decreased: hypothyroidism, renal failure

-Catecholamines

oncreased: phoechromocytoma

-Free Cortisol

-increased: cushing syndrome

Creatinine

decreased: renal disease

Protein

nephrotic syndromes, peeclampsia

Urine Microalbumin

-Used as screening tool for diabetic pts for risk of nephropathy

tx: ACE inhibitor/ARB

Urine Electrolytes

-Urine can be used as a "Spot Test" for various electrolyte abnormalities and metabolic states

Urine Sodium:

-<10 mEg: Hyponatremia, volume depletion

->20 mEg: SIADH, ATN

->40 mEg: ATN

Urine Potassium:

-<10 mEg: Hypokalemia, potassium depletion, extrarenal loss