Urinalysis and Body Fluids Review

Random Urine Specimen

Routine urinalysis (UA) collected anytime; not ideal since urine may be dilute & contaminated.

First Morning Urine Specimen

Routine UA collected upon awakening; best for screening as it is most concentrated.

2-Hour Postprandial Urine Specimen

Collected 2 hours after eating; best for detecting glycosuria.

24-Hour Urine Specimen

Quantitative chemical tests; discard 1st void on day 1, collect all urine for next 24 hours, including first void at same time on day 2.

Clean Catch Urine Specimen

Routine culture; cleanse external genitalia & collect midstream in sterile container to reduce contamination.

Catheterized Urine Specimen

Culture collected by inserting a catheter into the urethra to avoid contamination.

Suprapubic Aspiration

Culture collected by inserting a needle through the abdomen into the bladder to avoid contamination.

Normal Daily Urine Volume

600-2,000 mL with an average of 1,200-1,500 mL.

Normal Day-to-Night Urine Ratio

2:1-3:1.

Diuresis

Increased urine production.

Polyuria

Marked increase in urine flow; Adult: >2,500 mL/day; Children: 2.5-3 mL/kg/day.

Oliguria

Marked decrease in urine flow; Adult: <400 mL/day; Children: <0.5 mL/kg/hr; Infants: <1 mL/kg/hr.

Anuria

No urine production.

Urine Color Normal

Yellow due to urochrome.

Dilute Urine Color

Colorless, pale yellow.

Concentrated Urine Color

Dark yellow, amber.

Bilirubin in Urine

Amber, orange, yellow-green; yellow foam on shaking.

Urobilin in Urine

Amber, orange; no yellow foam on shaking.

Homogentisic Acid in Urine

Normal on voiding; brown or black on standing.

Melanin in Urine

Brown or black on standing.

Methemoglobin in Urine

Brown or black.

Myoglobin in Urine

Red; brown on standing.

Blood/Hemoglobin in Urine

Pink or red when fresh; brown on standing.

Porphyrin in Urine

Port-wine.

Drugs, Medications, Food Effects on Urine Color

Green, blue, red, orange.

Pseudomonas Infection Urine Color

Green, blue-green.

Bilirubin

Liver disease, biliary obstruction. Only conjugated bilirubin is excreted in urine.

Urobilinogen

1 Ehrlich unit or 1 mg/dL. Liver disease, hemolytic disorders. Reagent strips don't detect absence of urobilinogen, only ↑.

Nitrite

Some bacteria reduce nitrates to nitrites. 1st am specimen best. ↑sensitivity when urine in bladder at least 4 hr.

Leukocyte esterase

Longest rxn time. Detects intact & lysed grans & monos, not lymphs. Can be used with nitrite to screen urines for culture.

Specific gravity (SG)

Random specimen: 1.003-1.030. Only measures ionic solute. Not affected by urea, glucose, radiographic contrast media, plasma expanders. Not always same as SG by refractometer. Indication of kidney's concentrating ability & state of hydration. ↑in diabetes mellitus due to glucose. ↓in diabetes insipidus due to ↓ADH.

False-neg enzymatic rxns

Failure to bring refrigerated specimens to RT before testing.

False-neg leukocyte, blood

Failure to mix specimen well. WBCs, RBCs settle out.

Erroneous results

Failure to follow manufacturer's instructions.

False-neg rxns

Prolonged dipping. Reagents may leach from pads.

Expired strips

Erroneous results.

Highly pigmented urine

Pigment masks true rxns. Test by alternate method.

pH

Improperly preserved specimen. Acid runover from protein square.

Protein

Proteins other than albumin.

Glucose

Unpreserved specimen, ↑ascorbic acid, ↑SG, ↓temp.

Ketones

Improper storage. Acetone is volatile. Bacteria break down acetoacetic acid.

Blood

Menstruation, oxidizing agents, bacterial peroxidase.

Oxidizing agents

Chemical substances that can accept electrons from other substances.

Formalin

A solution of formaldehyde in water, used as a preservative.

Nitrofurantoin

An antibiotic used to treat urinary tract infections.

Vaginal discharge

Fluid that is expelled from the vagina, which can indicate various health conditions.

Specific gravity

A measure of the concentration of solutes in urine.

↑protein

Indicates an increase in protein levels in urine, which may suggest kidney issues.

Alkaline urine

Urine with a pH of 7.0 or higher, indicating a basic environment.

Microalbumin

Albumin in low concentration, indicative of early kidney damage.

Immunoassay

A laboratory technique that uses antibodies to detect specific substances.

Albumin-to-creatinine ratio (ACR)

A test comparing the amount of albumin to creatinine in urine, used to assess kidney function.

Diabetic nephropathy

Kidney damage resulting from diabetes, often indicated by elevated microalbumin levels.

Acid precipitation

A method used to confirm the presence of proteins in urine.

Sulfosalicylic acid (SSA)

A reagent used to test for proteins in urine.

Clinitest

A test that detects reducing substances in urine.

Copper reduction

A method used to detect glucose and other reducing sugars in urine.

Acetest

A test that detects ketones in urine using the sodium nitroprusside reaction.

Diazo reaction

A chemical reaction used to detect bilirubin in urine.

Epithelial Cells in the Urine Sediment

Cells shed from the lining of the urinary tract, observed in urine samples.

Squamous epithelial cell

A type of epithelial cell originating from the lower urethra or vagina.

Transitional epithelial cell

Cells that line the renal pelvis, ureters, bladder, and upper urethra.

Renal tubular epithelial cell

Cells originating from the renal tubules, indicative of tubular necrosis or damage.

Oval fat body

A renal tubular epithelial cell containing fat droplets, often seen in certain kidney diseases.

White blood cell (WBC)

Cells that are part of the immune system, often present in urine during infections.

Origin of WBC

Kidney, bladder, or urethra

Clinical significance of WBC

Cystitis, pyelonephritis, tumors, renal calculi. Normal: 0-8/HPF. Clumps of WBCs associated with acute infection. Seen in hypotonic urine.

Glitter cell

Same as WBC. WBC with Brownian movement of granules. Stain faintly or not at all.

Red blood cell (RBC)

Biconcave disk, about 7 µm. Smooth. Non-nucleated.

Origin of RBC

Kidney, bladder, or urethra

Clinical significance of RBC

Normal: 0-3/HPF. Crenate in hypertonic urine. Lyse in hypotonic urine & with 2% acetic acid. Infection, trauma, tumors, renal calculi. Dysmorphic RBCs indicate glomerular bleeding.

Amorphous urates

Irregular granules. Form pink precipitate in bottom of tube. May obscure significant sediment. Dissolve by warming to 60ºC. Birefringent. Polarizes light.

Uric acid

Pleomorphic. 4-sided, 6-sided, star-shaped, rosettes, spears, plates. Colorless, red-brown, or yellow.

Calcium oxalate

Octahedral (8-sided) envelope form is most common. Also dumbbell & ovoid forms. Occasionally found in slightly alk urine. Monohydrate form may be mistaken for RBCs. Most common constituent of renal calculi. From oxalate-rich foods.

Amorphous phosphates

Irregular granules. Form white precipitate in bottom of tube. Dissolve with 2% acetic acid.

Triple phosphate

"Coffin-lid" crystal.

Ammonium biurate

Seen in old specimens. Yellow-brown "thorn apples" & spheres.

Calcium phosphate

Only needle form seen in alkaline urine. Needles, rosettes, "pointing finger". Colorless dumbbells or aggregates.

Leucine

Often seen with tyrosine. Severe liver disease. Yellow, oily-looking spheres. Radial & concentric striations.

Tyrosine

Often seen with leucine. Severe liver disease. Fine yellow needles in sheaves or rosettes.

Cystine

Hexagonal (6-sided). Cystinuria. Must differentiate from uric acid. Doesn't polarize light. Confirm by cyanide-nitroprusside test.

Cholesterol

Nephrotic syndrome. Birefringent. Flat plates. Notched out corners. "Stair-steps."

Hyaline cast

Homogeneous with parallel sides, rounded ends. Normal: 0-2/LPF. ↑with stress, fever, trauma, exercise, renal disease. Most common type. Least significant. Tamm-Horsfall protein only. Dissolve in alk urine. Same refractive index as urine; may be overlooked with bright light.

Granular cast

From disintegration of cellular casts.

Granular Casts

From disintegration of cellular casts. Same as hyaline, but with granules. Normal: 0-1/LPF. ↑with stress, exercise, glomerulonephritis, pyelonephritis.

RBC Casts

IDs kidneys as source of bleeding. Most fragile cast. Often in fragments. RBCs in cast matrix. Yellowish to orange color. Acute glomerulonephritis, strenuous exercise.

Blood Casts

From disintegration of RBC casts. Same as RBC cast. Contain hemoglobin. Yellowish to orange color.

WBC Casts

IDs kidneys as site of infection. Pyelonephritis. WBCs in cast matrix. Irregular in shape.

Epithelial Cell Casts

Renal tubular damage. Renal tubular epithelial cells in cast matrix. Transitional & squamous epithelial cell aren't seen in casts. Distal to renal tubules & collecting ducts where casts are formed.

Waxy Casts

Urinary stasis. From degeneration of cellular & granular casts. Unfavorable sign. Homogeneous, opaque, notched edges, broken ends.

Fatty Casts

Nephrotic syndrome. Casts containing lipid droplets. Maltese crosses with polarized light if lipid is cholesterol. Sudan III & Oil Red O stain triglycerides & neutral fats.

Broad Casts

Advanced renal disease. Formed in dilated distal tubules & collecting ducts. 'Renal failure casts.' Wide. May be cellular, granular, or waxy.

Bacteria

Rods, cocci. UTI or contaminants. If clinically significant, WBCs present (unless patient is neutropenic).

Yeast

5-7 µm. Ovoid, colorless, smooth, refractile. May bud & form pseudohyphae. Add 2% acetic acid to differentiate from RBCs. RBCs lyse; yeast don't. Pseudohyphae indicate severe infection. WBCs are present in true yeast infections. Usually due to vaginal or fecal contamination. May be due to kidney infection. Often in urine of diabetics.

Sperm

4-6 µm head, 40-60 µm tail. Usually not significant in adult. May be sign of sexual abuse in child.

Trichomonas

Parasitic infection of genital tract. More common in females. Don't report unless motile. Resembles WBC. Flagella & undulating membrane. Rapid, jerky, nondirectional motility.

Mucus

Transparent, long, thin, ribbon-like structure with tapering ends.

Acute Glomerulonephritis

Protein, blood. Inflammation & damage to glomeruli. RBCs (some dysmorphic), WBCs, hgb casts. Frequently follows untreated group A strep infection.

Nephrotic Syndrome

Protein (large amount). Increased glomerular permeability. Hypoproteinemia, hyperlipidemia. Casts (all kinds), free fat & oval fat bodies.

Kidney Infection (Pyelonephritis)

WBCs, WBC casts, bacteria. Protein, leukocyte esterase, nitrite.