Sediment Constituents (Casts) Flashcards
What is the term for molds of the renal tubule?
Cylindruria
What does cylindruria represent?
Biopsy of individual tubule
What is the uniform diameter of the renal tubule mold in relation to RBCs?
7-8 times the diameter of RBCs
What is the most difficult and most important urinary sediment constituent?
Casts
Where are casts primarily formed in the kidney?
DCT and Collecting Duct
What is the major constituent of casts?
Uromodulin (Tamm Horsfall Protein)
What has the same significance as casts?
Cylindroids
How are casts examined?
Along the coverslip edges with subdued light
Under what magnification are casts counted?
LPF (Low Power Field)
Under what magnification are casts identified?
HPF (High Power Field)
What is the first step in the formation of casts?
Aggregation of uromodulin into individual protein fibrils attached to RTE cells
What is the last step in the formation of casts?
Excretion of casts
What is the order of cast degeneration?
Hyaline, Cellular, Degenerating cellular, Coarsely Granular, Finely granular, Waxy
What is the prototype cast and most frequently encountered?
Hyaline cast
What is the appearance of a hyaline cast?
Colorless and translucent, requires subdued light
What is the normal value of hyaline cast in urine?
0-2/LPF
What pathologies cause hyaline casts?
Glomerulonephritis, pyelonephritis, CHF, CKD
What is the most fragile cast that indicates bleeding within the nephron?
RBC Cast
What is the color of an RBC cast?
Orange-red
In what conditions is RBC cast significant?
Glomerulonephritis, strenuous exercise (physiologic cause in hyaline cast)
What is a muddy brown cast composed of?
Hemoglobin from lysed RBCs
What is the color and appearance of a blood (hemoglobin) cast?
Orange-red, homogeneous appearance
What cast indicates inflammation or infection within the nephron?
WBC/Leukocyte/Pus cast
What is required to distinguish WBC casts?
Phase microscope and supravital stain
In what conditions are WBC casts significant?
Pyelonephritis, acute interstitial nephritis
What is not a true cast but a clump of leukocytes?
Pseudoleukocyte casts
Where are pseudoleukocyte casts seen?
Lower UTI (without matrix)
What type of cells are visible on the cast matrix in Epithelial (RTE) casts?
Smaller, round and oval cells
What is the significance of Epithelial (RTE) casts?
Advanced tubular destruction, tubular damage
How is a bacterial cast confirmed?
Gram stain
What is the significance of bacterial casts?
Pyelonephritis
Where are the granules of granular casts derived from?
Lysosomes of RTE cells during normal metabolism (nonpathologic)
What is the appearance of a fine granular cast?
Sandpaper
What possible casts are seen in pyelonephritis?
Bacterial, WBC casts, Granular Cast (Coarse and Fine)
What is the significance of granular casts?
Glomerulonephritis, pyelonephritis, stress, strenuous exercise
What does the Sternheimer-Malbin stain?
Cast matrix (not fat globules)
How is cholesterol seen in casts?
Polarizing microscope
What is the significance of fatty casts?
Nephrotic syndrome, toxic tubular necrosis, diabetes mellitus, crush injuries
What is the final degenerative form of all types of casts?
Waxy casts
What is the appearance of waxy casts?
Ground glass
What is the significance of waxy casts?
Urinary stasis, chronic renal failure, ESRD
What is often referred to as a Renal Failure Cast?
Broad cast
What does a broad cast indicate?
Destruction (widening) of the tubular walls
What is the appearance of broad casts compared to ordinary casts?
2-6x wider than ordinary casts
What is the significance of broad casts?
Extreme urine stasis, renal failure
What is the appearance of a miscellaneous cast that incorporates bilirubin color?
Golden-brown
What is the appearance of a miscellaneous cast that incorporates hemoglobin or myoglobin color?
Yellow to red-brown
What is a cast containing multiple cell types called?
Mixed cellular casts
What is the composition of a mixed cellular cast in glomerulonephritis?
RBC and WBC casts
What is the composition of a mixed cellular cast in pyelonephritis?
WBC and RTE casts or WBC and bacterial casts
What types of casts contain urates, calcium oxalate, and sulfonamides?
Crystal casts
Where are crystal casts formed?
Tubule or collecting duct