Urinary casts form in the distal nephron and indicate kidney disease. They are cylindrical aggregations of particles that precipitate from Tamm-Horsfall mucoprotein secreted by renal tubule cells. Different types of casts provide information about underlying kidney conditions - hyaline casts are common, granular casts suggest chronic kidney disease, and red blood cell casts indicate glomerular damage. Urinary crystals also form in the urine and can provide some clinical information, though many patients with crystalluria do not develop kidney stones. The type of crystal present depends on urine pH and composition.

1. by Dr.Vivekanandan
Urinary Casts
Theyare cylindrical aggregationsof particlesthatforminthe distal nephron,dislodge,andpassintothe urine.Inurinalysis they indicate kidneydisease.
Theyformvia precipitationof Tamm-Horsfall mucoprotein whichissecretedby renal tubulecells.
Acellular casts Cellular casts
Hyaline casts Red cell casts
Granular casts White cell casts
Waxycasts Epithelial casts
Fatty casts
Hyaline casts :
The most commontype of cast, hyaline castsare solidified Tamm-Horsfallmucoprotein
secretedfromthe tubularepithelial cells.Seeninfever&after strenuousexercise
Granular casts :
Granular casts can result from breakdownof cellularcastsorthe inclusionof aggregatesof
plasmaproteins orimmunoglobulinlightchain,indicative of chronickidneydisease
Waxy casts :
Waxycasts suggestlongstandingkidneydisease
Fatty casts :
Formedbythe breakdownof lipid-richepithelialcells,these are hyaline castswith
fat globule inclusions,presentinnephroticsyndrome, diabeticorlupusnephropathy,
acute tubularnecrosis
Red blood cell casts :
The presence of redbloodcellswithinthe castisalwayspathologic,and isstrongly
indicative of glomerulardamage.Theyare usuallyassociatedwith nephriticsyndromes.
White blood cell casts :
Indicative of inflammation orinfection,pyelonephritis,acute allergicinterstitialnephritis,
nephroticsyndrome, post-streptococcal acute glomerulonephritis
Epithelial casts :
Thiscast is formedbyinclusionoradhesionof desquamatedepithelialcellsof the tubule lining,
seeninacute tubularnecrosis andtoxicingestion,suchasfrom mercury,diethyleneglycol,orsalicylate

2. by Dr.Vivekanandan
Urine Crystals
Exceptfor the cystine crystalsanda fewothers,the majorityof crystalsfoundinthe urinarysedimentare of limited clinical value.Itistempting toassociate
crystalswitha riskof urolithiasis,butthe majorityof patientswithacrystalluriadonothave andwill notdevelopkidneystones.Manybenignsituations can
provoke crystal formation. Inthe majorityof cases,the crystalsfoundinurine are not presentinthe freshlyvoidedspecimen.Alkalizationandrefrigeration
are promotersof crystalsformation.
Crystals in acidic urine Crystals in alkaline urine
Uric acid Ammonium magnesium phosphates
Calciumoxalate Calcium carbonate
Leucine
Cysteine
Uric acid and Urates :
Amorphousuratesappearasred granulesandare dissolvedbyheatandsodiumhydroxide
but notacetic acid. Uric acid crystalsvary inshape and are yellow brownincolourandare not
dissolvedbyheat,aceticacidorHcl but are soluble whenheatedwithsodiumhydroxide.
Seenindisturbancesof uricacidmetabolism, duringfeverwhen the urine isconcentrated.
Calcium Oxalate :
Commonlyfoundin dietsrichintomatoes,spinachetc.Typicallyenvelope shaped crystalsbut
occasionally dumb- bell shaped.Insoluble instrongHcl.
Cystine :
Highlyrefractile,hexagonal plates.They are soluble inHcl butinsolubleinaceticacid.Theyare seen
incystinosis whichisaninbornerror of metabolisminwhichcystinecrystalsare foundinthe urine,
reticuloendothelial systemandeyes.
Leucine :
Slightlyyellow,oilylookingsphereswithradial andconcentricstriations.Theyare notsoluble inHcl
or ether. Theyare foundin liverdisorders
Ammonium MagnesiumPhosphates: ( Triple phosphate)
Theyare featheryorleaf like forms.Infreshlypassedurinetheyindicate stonesinthe bladder
or kidney. Dissolves inaceticacid.
Dicalcium Phosphates :
Theyare alsoseeninslightlyacidorneutral urine.Theyare colourlessprismsarrangedinstars
and rosettes.Theyare soluble inaceticacid.
Calcium carbonate:
Amorphousgranulesorcolourlessspheresanddumb-bellswhichare solubleinaceticacid
withgas formation. Occursinalkaline urine.