Urine and Body Fluids

 

Introduction to UA

Urine – easily collected and available specimen

·         Aids in disease diagnosis, asymptomatic screening, monitor disease progression and therapy effectiveness

·         UTIs – infections of urinary tract that are often screened in UA

o   Cystitis – infection of bladder and lower UT

o   Nephritis – Kidney inflammation

§  NO infection – glomerulonephritis

§  INFECTION – Pyelonephritis

o   Nephrosis/Nephrotic syndrome – non-inflammatory/degeneration of kidney

Renal system overview – filtration and fluid homeostasis

·         Kidneys – urine formed from blood filtration

·         Ureters – carries urine to bladder

·         Bladder – storage of produced urine

·         Urethra – delivers urine to outside world

o   Blood pressure and blood flow determine kidney function

o   Series of reabsorption and secretions

·         Hilus – section of kidney where ureters, renal artery, and renal vein intersect

·         Adrenal glands – miter shaped glands above kidneys, endocrine

·         Cortex – outer part of kidney

·         Medulla – inner section

·         Renal Pelvis – where filtrate begins to enter ureter

o   Columns and pyramids

 Renal Blood Flow and Glomerulus

·         Arrives via afferent arteriole

o   Glomerulus – ball of fenestrated capillaries

o   BP forces water and solutes through GBM and Podocytes into Bowman’s capsule

o   Remaining blood leaves via efferent arteriole – becomes vasa recta and PTC

Urine formation

·         Similar to plasma = ultrafiltrate

·         170 L of fluid/plasma filtered a day

·         Average urine output is 1.2 L

·         Composition

o   Variations in diet and activity

o   Urea is approximately 50% of dissolved organic solute

§  AA breakdown

o   Major inorganic solutes: Chloride, Potassium, Sodium

§  Lesser extent calcium and magnesium

o   Urea and creatinine – identifiers of urine (Creatinine – muscle breakdown)

o   Ammonium – tissue fluid acidity regulator

o   Watch for mucus, cells, casts, bacteria

Not Normally in Urine = blood, bilirubin, glucose, ketones, proteins, most formed elements

Volume – normal range is .6 Liters to 2 Liters – influenced by fluid loss and ADH

Definitions

·         Oliguria – less than 400 mL of urine a day in adults, scant amounts

o   Vomiting, diarrhea, acute nephritis

·         Anuria – complete cessation of all urine flow

o   Severe kidney damage

·         Nocturia – increased urine excretion at night

o   Prostate issues

·         Polyuria – greater than 2.5 liters of urine a day

Diabetes

DM – Diabetes Mellitus, very high specific gravity (sugar in urine), polydipsia and polyuria

DI – Diabetes Insipidus, very LOW specific gravity, dilute, polydipsia and polyuria

Collection

·         Gloves, leak proof containers, screw caps

·         12 mL “minimum” for analysis

·         Large 24 hour plastic containers

·         Name/ID, DOB on label

·         Label on container/not lid – must match requisition form

·         Reject unlabeled, QNS, too much lapse, too much contamination

Must test within 2 hours of collection

·         Refrigerate 2-8 degrees Celsius and chemically preserve if greater than 2 hours

·         Increased color, turbidity and pH (bacteria) – decreased glucose, ketones, bilirubin, formed elements

o   Return to RT before testing

·         Preservatives

o   Boric Acid – growth preventer for bacteria, keeps pH at 6.0

o   Formalin – sedimentation preserver

§  Others – Sodium Borate, Sodium Formate, Sodium Propionate

Types of specimens

·         Random – anytime, most common

·         First morning – basal state, orthostatic proteinuria check, more concentrated

·         24 hour specimen – diurnal variations, mix thoroughly and record volumes

o   Void in morning, then collect including next morning’s void

·         2 hour post prandial (post meal)

o   Compare before and after meal, monitor insulin therapy and diabetes

§  Glucose Tolerance Urine – similar to blood, not used

·         Midstream Clean-Catch

o   Cleanse urethral opening, void first in toilet, then collect, finish in toilet

·         Catheter specimen – bacterial culture, may be ‘sterile’

·         Suprapubic Aspirate – needle introduced to bladder – often pediatric

·         Prostatitis specimen – three sample collection

o   First collection, Second mid-stream, third is post prostatic massage

§  2 – control for UTI / 3 is indicative of prostate infection

o   Two specimen collection (before and after)

·         Drug specimen – need to maintain chain of command (documenting times and initials)

o   Reporting temperatures for body range check

o   Withstand legal scrutiny

o   Often requires Photo ID

Myoglobin urine – often from rhabdomyolysis – extreme trauma to muscle

 

Microscopy Review: Cells, Casts, Crystals and Intro

Sediment analysis – centrifuging 10-15 mL of urine at 2000 RPM for 5 minutes

Pour off supernatant but resuspend sediment in 1mL – continually adjust up and down

            Low power 10x – casts and mucus

            High power 40x – everything else

Sternheimer-Malbin Stain – Crystal violet and safranin in ethanol

Phase contrast – watch for halos                                                         RBCs

RBCs

Indicative of urinary tract damage

Menstrual contamination

Watch for ghosts in hypotonic urine

Crenation in hypertonic

            Confused with WBCs and Yeast

            2% Acetic acid lyses cells

            Correlate to strip – protein positive                                           WBCs

WBCs

Smaller than renal, larger than red

Almost always neutrophils

Clumping, granules, lobes

Indicative of infection - Pyelonephritis

Glomerularnephritis – inflammation                                                     Group of RTEs

 

Epithelial cells – differentiation among types

Renal Tubular cells originate in Convoluted Tubules

            Larger than WBCs, large round but off-center nucleus, may be cuboidal

            Tubular damage: Pyelonephritis, salicylate intoxication, renal rejection

 

May incorporate fat and become oval fat body – degeneration                     Oval fat body

            Sudan III – oil droplet staining red

            Not detected chemically, fatty tubule degeneration

            Nephrotic Syndrome, Diabetes Mellitus, Eclampsia, Injuries of subcutaneous fat

 

 

 

 

 

Transition originate in upper urethra or renal pelvis                                Transitional/Urothelial

            May have tail like projections or be pear shaped with two nuclei

 

Squamous – vaginal contamination or lower urethra, non-disease

            Most abundant, scallop shape, small nuclei in center

            Often folded over shape, not significant

 

 

 

 

 

 

 

 

 

 

 

 

Bacteria – should not be present but can be contamination

Watch for positive nitrite test, often appear with WBCs - correlate

 

 

Yeast – watch for budding

            Often mistaken for RBCs

            C. albicans most common

            Often found in diabetic patients, sugary urine

            Pseudohyphae – long chains that branch

 

 

Sperm – oval bodies with tails, usually immobile

            Male or female

 

Parasites – watch for WBCs, may be parasite

            May also be contamination from feces or vagina                    Trichomonas Vaginalis

Trichomonas vaginalis – frequent in women with vaginitis, motility required to report out

            Small balls with outer halo and flagellum

Enterobius vermicularis – pinworm

            Developing larva resemble footballs

            Transparent shell of egg

                                                                                                            Enterobius vermicularis

 

Artifacts – contamination

Vegetable and hair fibers, air bubbles

 

 

Crystals – Usually not of any significance, may appear upon standing especially in refrigeration

            Those of clinical significance: Cystine and Leucine crystals

                        Sulfonamide crystals form from high doses (also salicylates)

            Affected by pH and solute concentration

Polarization – aids in identification, two polarizing fields, watch which polarize light

            Birefringence – ability to refract in two directions

            Negative birefringence – left rotation and yellow

            Positive birefringence – right rotation and blue

Most common in acidic urine – uric acid and calcium oxalates

            Often amorphous urates, purine metabolism and nucleic acid breakdown, GOUT

Negative birefringence

 

 

 

 

 

            Can be football shaped or in clusters

            Amorphous urates – often from refrigeration, pink precipitate (sandy background)

 

 

 

 

 

Calcium oxalate – found in acidic but can be in neutral, found with excessive rhubarb or spinach

            Oxalate high foods, may be indicative of renal calculi/stones

            Appears like diamond shaped stones – x marks spot (bipyramidal)

            May also come in monohydrate form, dissolves in NaOH and HCl

 

 

 

 

Alkaline urine crystals – often includes triple phosphates and ammonium biurates

            Amorphous phosphates do occur

            Triple phosphates – coffin crystals, often found in renal calculi, dissolves in AA

            Polarizes light

 

 

 

 

 

Ammonium biurate – often found in alkaline urines, older specimens, abnormal if fresh

            Thorny apples, with yellow-brown sphere bodies

            Dissolves in Sodium Hydroxide

 

 

 

 

 

Abnormal metabolic urine crystals

Cystine – found in acid urine, indicative of amino acid disorder

            Cystinuria, refractile hexagons

            Dissolves in HCl and NaOH

 

 

Tyrosine crystals – seen in severe liver disease, acidic urine

            Bundles of hay appearance

            Dissolves in HCl and NaOH

 

Leucine – liver disease if with Tyrosine

            Wagon—wheel appearance, citrus sections

            Polarizes to Maltese cross

            Dissolves in NaOH

 

Cholesterol – acidic pH

Free fat from RTE degeneration

            Nephrotic Syndrome

            Chipped glass shape                                                                                      Cholesterol

            Dissolves in hot alcohol

 

Bilirubin – bilirubinuria

            No normal amount, acid urine

            Red brown bundles

            Dissolves in HCl and NaOH

 

 

 

 

 

 

 

 

 

Iatrogenic crystals – often of drug origin

Sulfonamide crystals – an indicator of antibiotic use, can cause damage as precipitate out in nephron

            Often yellow-brown and distinct clam shell shape

            Dissolves in NaOH, polarizes light                                        

 

Also radiographic crystals

            Like Renograin, look like knives

Artifacts – starch and talc

 

Casts – larger structures that form in lumen of DCT/PCT/LoH

            Formed from uromodulin protein

            May contain cells

            Increased proteins in urine

            Affected by acid pH, hypertonic solutions, stasis

            PARALLEL SIDES WITH ROUND/BLUNT ENDS

Width indicates diameter of tubule

            Broad – dilated or atrophied tubules/CD

            ALMOST ALWAYS PATHOLOGY – DAMAGE AND INFLAMMATION

Sequence of degeneration

Cellular – Coarse Granular – Fine Granular – Waxy

Hyaline cast – almost invisible/mucoid

            A few indicative of normal renal functioning

 

 

 

 

 

Red Cell cast

            Brown or colorless, can have many or few cells

Hematuria – conditions include renal trauma, lupus nephritis, acute glomerulonephritis, and Goodpasture Syndrome

                       

White cell cast

            Primarily neutrophils

            Indicative of renal infection/inflammation

            Acute pyelonephritis and lupus nephritis

 

 

 

 

 

Epithelial cell cast

            Rarely seen, often from urine stasis and desquamation of RTEs

            Lack of urine flow, seen in tubular necrosis

            After nephrotoxic agent exposure, kidney rejection

 

Granular Casts – Coarse

            Degeneration of cellular cast or protein aggregation

            NO clinical significance coarse or fine granular

            Indicate renal disease – remained long enough for degeneration

                        Can be from extreme exercise

 

 

Waxy casts – results from degenerated granular casts

            High refractive index

            Severe chronic renal failure, diabetic nephropathy, acute renal disease, kidney rejection

            Must be in urine a long time, may look like butter

 

Fatty casts – few to may droplets, Maltese cross

            Fatty degeneration of RTE cells

            Nephrotic syndrome, glomerulonephritis, diabetic glomerulosclerosis

 

 

 

 

 

 

 

Artifacts – Mucous threads, fibers, hairs, and yeast

 

Overview

Glomerulonephritis – see hematuria, may see RBC casts if acute or other casts if chronic

Pyelonephritis – Bacteria, WBCs, may see WBC casts if chronic

Nephrotic Syndrome – Oval fat bodies, fatty casts, fat droplets, waxy casts

Lower UTI – bacteria and WBCs