Cast and Crystal Composition

Casts

• come from the kidney

• form in DCT and collecting duct

What do casts indicate?

• conditions of the nephron

How are casta analyzed?

• detected under low power and identified under high power

Tamm Horsfall Protein

• secreted by RTE cells

  • ascending loop of henle

  • DCT

  • upper part of collecting ducts

TH protein gels

• urine stasis

• acid pH

• Na and Cl

How do casts form

• aggregated TH structure attached to RTE

• elements get trapped and form a solid matrix

• matrix detaches from RTE and is excreted as a cast

Hyaline Casts

• most frequently seen

• 0-2 per Ipf is normal

Nonpathologic reasons for hyaline casts

• stress

• exercise

• fever

• heat exposure

• dehydration

Pathologic reasons for hyaline casts

• glomerunephritis

• pyelonephritis

• chronic renal disease

• congestive heart failure

RBC Casts

• orange-red color

• should be confirmed by a positive reagent strip

What do RBC casts indicate

• bleeding within the nephron

• glomerular damage/nephron capillary damage

What are muddy brown casts associated with?

• acute tubular nephritis

What diseases are RBC casts associated with?

• acute glomerulonephritis

• nephritic syndrome

WBC Casts

• mainly neutrophils

• tightly packed

What is the clinical significance of WBC casts

• infection and inflammation of tubules

WBC casts AND bacteria

• pyelonephritis

WBC cast and NO BACTERIA

• acute interstitial nephritis

Fatty Casts

• seen with oval fat bodies and free fat droplets

• highly refratcile

What diseases are associated with fatty casts?

• nephrotic syndrome

• diabetes mellitus

• tubular necrosis

Granular Casts

• coarse and fine

• pathologic and nonpathologic oragines

Granules from granular casts disintegrate and form what?

• waxy casts

Waxy casts

• brittle, fragmented

• form from degranulated hyaline/granular casts

What do waxy casts represent?

• extreme urine stasis

• chronic renal failure

Broad Casts

• chronic renal failure casts

• form in the upper collecting duct

what casts are associated with widening of tubule walls?

• broad casts

How do you tell the difference between artifacts and casts?

• casts DO NOT POLARIZE

• artifacts/fibers will

FIndings of a lower UTI

• RBC

• WBC

• Trans. Epi

• BACTERIA

Findings of an upper UTI

• RBC

• WBC

• Renal Epi

• WBC cats

• RTE casts

• Gran. casts

FIndings of acute glomerunephritis

• RBC

• WBC

• Renal epi

• RBC casts

• WBC

• RTE casts

• Gran. casts

• Dysmorphic RBC

  • ancathocytes

Findings of chronic glomerulonephritis

• RBC

• WBC

• Renal Epi

• RTE casts

• Gran casts

• waxy casts

• BROAD CASTS

Findings of Nephrotic Syndrome

• RBC

• Renal epi

• Gran casts

• waxy casts

• fatty casts

• CHOLESTEROL CRYSTALS

Findings of Acute Tubular Necrosis

• RBC

• WBC

• Renal epi

• RTE cells

• gran casts

• waxy casts

• Proximal RTE and Collecting duct RTE

Findings of renal transplant failure

• RBC

• WBC

• renal epi

• WBC casts

• RTE casts

• gran casts

• LYMPHOCYTES

Urinary Crystals

• significant in freshly voided urine

• cause tubular damage/ formed in vivo

How are urinary crystals identified?

• appearance

• pH

How are crystals formed?

• precipitation of urine solutes

  • salt,organic compounds, medication

What is crystal formation based on?

• temperature

• solute concentration

• urine pH

• old urine

Crystals in fresh specimen are associated with what?

• high specific gravity

What is the most valuable identification for urinary crystals?

• urine pH

What helps in crystal identification?

• polarized microscopy

What contribute to formation and solubility of crystals?

• temperature

• pH

Amorphous urates

• form in refrigerated acid urine

• dissolve via heat

Amorphous Phosphates

• form in refrigerated alkaline urine

• dissolve via acetic acid

Amorphous urates

• pH >5.5

• urine sediment as pink color

What crystals form in acid urine?

• amorphous urates

• uric acid crystals

• calcium oxalate crystals

• cystine crystals

Uric Acid Crystals

• seen in patients with gout

Calcium oxalate crystals

• acid/neutral pH

• major component of renal calculi

Crystals seen in alkaline urine

• triple phosphate

• amorphous phosphates

• amonion biurate crystals

Triple phosphate cyrtsals

• coffin-lid shape

• seen in highly alkaline urine/ UTI

Amorphous phosphates

• seen in alkaline pH

• have heavy white precipitate after refrigeration

Ammonium Biurate crystals

• ONLY urate in alkaline urine

• found in old specimen and urea-splitting bacteria producing ammonia

Cystinuria

• inherited inability to reabsorb cystine

• form renal calculi

• cystine crystals will be present

Cystine crystals

• seen in acidic urine

• only thick cystine crystals will polarize

Cholesterol Crystals are associated with what disorders?

• nephrotic syndrome

• fatty casts

• oval fat bodies

Bilirubin Crystals

• seen in viral hepatitis/ tubular damage

• associated with positive reagent strip for bilirubin

Tyrosine crystals

• seen with leucine crystals

• inherited amino acid disorders

• positive bilirubin test

Leucine crystals

• yellow -brown speres

• positive bilirubin test

Ampicillin Crystals

• colorless needles that form bundles after refrigeration

• massive dosage with inadequate hydration

Sulfa Crystals

• most common to precipitate

• variety of shapes