chem: urinalysis crystals and casts

what is nephrolithiasis

kidney calculi (stones)

what crystal is soluble in acetic acid with bubbling?

calcium carbonate

amorphous urates are formed from urate salts of Na, K, Mg, and Ca usually during ___________

refrigeration (not usually seen in freshly voided urine

what crystal does this describe: appears following sample refrigeration (pink sediment), redissolved when heated to 60 degrees celcius

acid crystal: amorphous urates

what diseases/ disorders is uric acid associated with

• gout

• Lesch-Nyhan syndrome

• chemotherapy

• leukemia

• may be associated with kidney stone formation

• can be normal

what crystal is this? is it alk or acid?

uric acid crystal; acidic

amorphous urates can change to uric acid crystals in the presence of?????

concentrated HCl

what urine crystal is formed from oxalic acid in food (tomatoes, asparagus, spinach, berries, oranges)

calcium oxalate

what crystal is this? is it alk or acid?

calcium oxalate; acidic

what is the most common form of calcium oxalate?

dihydrate octrahedral (envelope shape)

what acidic crystal may be misidentified as red blood cells

ovoid forms of calcium oxalate

what is a chemical property of calcium oxalate and how would it help in identifying this crystal?

insoluble in acetic acid; if we are questioning what the crystal is we can add dilute acetic acid which will lyse rbcs but not calcium oxalate as they get mixed up when calcium oxalate is in its ovoid form.

what is the clinical significance of calcium oxalate in urine

• can be normal

• major component of renal calculi

what acidic crystal is the major component of renal calculi (kidney stones)

calcium oxalate

what crystal is seen in patients with ethylene glycol poisoning/ antifreeze poisoning

long form of monohydrate calcium oxalate

long form of monohydrate calcium oxalate are seen in patients dealing with what?

ethelyne glycol/antifreeze poisoning

what crystal is this? acid or alk?

long form monohydrate calcium oxalate

bilirubin crystals are soluble in?? insoluble in??

soluble in

• acetic acid

• HCl

• NaOH

• acetone

insoluble in

• alcohol

if you see a bilirubin crystal under the mic, but the dipstick is neg for bilirubin, what must you report?

re test. if neg again, dont call it a bilirubin crystal. bili crystals should always be accompanied by pos bili dipstick

clinical significance of bilirubin crystals

seen in many hepatic disorder (liver)

what crystal? acid or alk?

bilirubin; acidic crystal

most frequent cause of calculi in kids

cystine crystals

which crystal is being described: colourless, thin, hexagonal plates. exhibit slight/ no birefringence

cystine

cystine is soluble in??? insoluble in???

soluble in:

• HCl

• ammonia

insoluble in:

• acetic acid

how can you confirm that a crystal in the urine is a cystine crystal?

confirmed by a positive CYANIDE NITROPRUSSIDE TEST (purple/blue); if the test turns clear it is a negative result and the crystal is likely uric acid.

clinical significance of cystine crystals

• IEM: cystinura

• kidney stones in kids

what crystal is this? acidic or alk?

cystine; acidic

what crystal is being described: fine colourless to yellow/brown single needles. also seen as sheaves or rosettes

tyrosine

what are the key findings also found when tyrosine crystals are seen?

• often accompanied by pos BILI on dipstick

• Leucine crystals seen as well

clinical significance of tyrosine crystals

• associated w severe liver disease

• IEM: tyrosinemia

what crystal is this, is it acidic or akaline?

tyrosine; acidic

what crystal is being described: oily looking yellow brown spheroids with concentric rings around the outer edge and radial striations

leucine

key findings seen when leucine crystals are present

• often accompanied by positive bili on dipstick

• tyrosine crystals usually seen

clinical significance of leucine crystals

• associated with severe liver disease

• amino acid metabolism impairement

what crystal; acidic or alk?

leucine; acidic

what crystal: clear, flat plates w notched corners

cholesterol (no other crystal looks like dis)

what is the clinical significance of cholesterol crystals

• associated w nephrotic syndrome

• associated with disorders that produce lipiduria

what other findings are seen along side cholesterol crystals

• can appear when urine is refrigerated

• usually accompanied by pos protein on urine test pad

• oval fat bodies, fatty casts, free fat droplets may also be seen in the sediment

what crystal; acid or alk?

cholesterol; acid

what crystal; acid or alk?

sulfonamide (antibiotic); acid

what crystal is being described: flat needles, sheaves of small needles or as spheroids. often brown in color

sulfonamide

if suspecting sulfonamide crystals what must you do confirm that these crystals are actually there?

• should consult the floor to see if said drug is/was being administered

• biochemically test urine for sulfa before reporting. sulfa must be pos

what crystal is being described: flat needles or sheaves accompanied by round globules but are variable in form

radiopaque dye/ contrast dye

what is the specific gravity of urine when it has radiopaque dye in it (measured by refractometer)

>1.035

what must you do before reporting that there is radiopaque dye in a patient’s urine

must confirm via the ordering location that the patient recieved contrast media

what crystal; acid or alk

radiopaque dye; acidic

how do we tell the difference between amorphous urates and amorphous phosphates

• they are identical visually but amorphous phosphates are soluble in acetic acid while urates are not.

• upon refrigeration, amorphous phosphates precipitate out white while urates are pink

• when heated at 60 degrees celcius they do not redissolve unlike urates

what crystal: coffin lid or fern leaf (if freshely formed) form

triple phosphate/ struvite

struvite/ triple phosphate is formed from?

• ammonium

• magnesium

• phosphate

what crystal ; acid or alk?

struvite/triple phosphate; alkaline

what crystal: large, flat shaped rectangular plates or wedge shaped prisms, often appearing in rosettes.

calcium phosphate

what crystal; acid or alk

calcium phosphate; alk

what crystal: yellowish brown “thorn apple” shape (round with thorny projections) or in spherical form

ammonium biurate crystal

presence of ammonium biurate crystals indicates what? how would you report it

old/ poorly preserved urine specimen. reject and request recollect

what crystal; acid or alk

ammonium biurate; alkaline

what alkaline crystal is often misidentified as RBCs

calcium carbonate

what crystal: small, colourless granules/dumbells

calcium carbonate

what crystal effervesces w HCl or acetic acid ? *

calcium carbonate

what crystal; alk or acid

calcium carbonate; alk

what crystal is seen as long thin needles following a certain antiviral therapy

acyclovir (antiviral drug) crystals

we find what looks like a circular crystal in the urine of an elderly male patient. under a polarized microscope it looks to have a maltese cross pattern. what is this likely

starch crystal

what is this

pinworm ova

what dis

schistosoma ova (parasite)

what dis

pollen

what is the major constituent in a cast?

tamm horsfall (TH) protein aka: uromodulin

factors promoting cast formation

• increased amts of plasma proteins entering tubules

• decreased pH

• decreased urinary flow rate

• increased urine concentration

• sodium and calcium present

what cast: clear, colourless; parallel sides and rounded ends.

hyaline cast (most commonly seen)

normal amt of hyaline casts in urine

0-2/ lpf (can be a product of exercise)

pathological reason for increased hyaline casts

• increased acute glomerulonephritis

ALL cellular casts arise from the _____ tubules. what is it made of?

distal tubules; TH protein matrix with rbcs, wbcs, renal tubular epi cells (always clinically significant)

rbc casts indicate?

bleeding w in nepherons

what are the other key findings associated with rbc casts

• free rbcs

• pos blood dipstick

• pos pro dipstick

what is the most diagnostic element in urinary sediment?

rbc cast

rbc casts are primarily indicative of what disease/ state?

glomerulonephritis (exception: if hit in the kidneys rlly hard or vvv strenuous exercise)

what cast

hyaline cast

what cast

rbc cast

what cast

wbc cast

what is the clinical significance of wbc casts

• associated w inflammation or infection w in the nephron

• pyelonephritis (upper UTI of pelvis and parenchyma of the kidney

what is the primary marker to distinguish between pyelonephritis and lower UTIs

WBC casts

present in pyelonephritis and not present in lower UTIs

what does the presence of epithelial casts indicate

renal tubular damage

• heavy metal toxicity/ chemical induced toxicity

• viral infections

• may be seen w wbc casts in pyelonephritis

what cast

epithelial cell cast

what cast: composed of plasma protein aggregates and cellular remnants that look like granules incorporated into cast matrix

granular casts

what do granular casts represent

disintegration of cellular casts

if granular casts are seen with hyaline casts, what is the significance? what if they are seen with cellular casts?

normal;disease

what do granular casts in urine specifically mean pathologically?

not indicative of any specific renal disorder, just lets us know that there is something happening in the kidneys

if there is a waxy cast in patient urine what would it indicate

• represent increased urine stasis

• indicates chronic to end stage renal disease= kidney failure

what cast

granular cast

what cast

waxy cast

what are broad casts

aka renal failure casts

• represents extreme urine stasis (anuria) and destruction/ widening of the tubule

when are fatty casts seen

• usually associated with nephrotic syndrome (rot= protein)

acute glomerulonephritis urinalysis findings

test strip: POS BLOOD, POS PRO

microscopic: rbcs, wbcs, rte cells, hyaline casts, granular casts, rbc casts

chronic glomerulonephritis urinalysis findings

test strip: POS BLOOD , POS PRO

microscopic: rbcs, wbcs, rte cells, hyaline casts, granular casts, rbc casts, waxy, and broad casts

describes what disease: immune response to strep infection resulting in hematuria, proteinuria, casts in urine

acute glomerulonephritis

what state does this describe: end stage glomerular damage with loss of renal function

chronic glomerulonephritis

what disease/ state: increased permeability of the glomerulous causedby toxins/ drugs, diabetes mellitus, infections, etc (loss of lots of alb)

nephrotic syndrome

urinalysis findings of nephrotic syndrome

test strip: POS PROTEIN (BC ALB IN URINE), MAY SEE POS BLOOD

microscopic: wbc, fat droplets, oval fat bodies, fatty casts, waxy casts, cholesterol crystals (can see rbcs)