Microscopic Analysis of Urine PDF

Microscopic analysis of urine URINARY CAST  CYLINDRURIA– term for the presence of urinary cast Casts are the only elements found in the urinary sediment that are unique to the kidney. The major constituent/mould /template/ matrix of cast is UROMODULIN which is secreted by...

Microscopic analysis of urine URINARY CAST  CYLINDRURIA– term for the presence of urinary cast Casts are the only elements found in the urinary sediment that are unique to the kidney. The major constituent/mould /template/ matrix of cast is UROMODULIN which is secreted by the RTE Cells. The protein (uromodulin) gels more readily under conditions of urine-flow stasis, acidity, and the presence of sodium and calcium. Uromodulin protein is found in both normal and abnormal urine Casts are Formed in DCT, and Collecting duct Examination of casts should be performed along the edges of the cover slip.  Cylindroids are formed at the ALH and DCT with tapered end or have a tail at the other tail. They have the same significance as casts (hyaline cast). Cylindroids are product of incomplete cast formation, or cast disintegration. CAST FORMATION From least significant to the most significant Hyaline Cast→ Cellular cast→ Coarse granular cast → Fine granular cast → Waxy cast → Broad Cast Step by Step Analysis of the Formation of Tamm-Horsfall protein matrix 1. Aggregation of Tamm-Horsfall protein into individual protein fibrils attached to the RTE cells 2. Interweaving of protein fibrils to form a loose fibrillar network (urinary constituents may become enmeshed in the network at this time) 3. Further protein fibril interweaving to form a solid structure 4. Possible attachment of urinary constituents to the solid matrix 5. Detachment of protein fibrils from the epithelial cells 6. Excretion of the cast DIFFERENT TYPES OF CASTS HYALINE CAST Most frequently seen cast which consists almost entirely of uromodulin Pro – cast Hyaline casts appear colorless in unstained sediments and have a low refractive index similar to that of urine; thus, they can easily be overlooked if specimens are not examined under subdued light The morphology of hyaline casts is varied, consisting of normal parallel sides and rounded ends, cylindroid forms, and wrinkled or convoluted shapes that indicate aging of the cast matrix  The accompanying dehydration of the protein fibrils and internal tension may account for the wrinkled and convoluted appearance of older hyaline casts Sternheimer-Malbin stain and KOVA stain: Pink-color Normal value: 0-2 /low power field ➔ Physiologic increase- Strenuous exercise, Dehydration, Heat exposure, Emotional stress ➔ Pathologic increase- Acute glomerulonephritis, Pyelonephritis, Chronic renal disease, Congestive heart failure RBC CAST Seen during bleeding in the nephron, especially associated with glomerulonephritis RBC casts are easily detected under low power by their orange-red color. They are more fragile than other casts and may exist as fragments or have a more irregular shape as the result of tightly packed cells adhering to the protein matrix They have also been observed in healthy individuals following participation in strenuous contact sports As an RBC cast ages, cell lysis begins and the cast develops a more homogenous appearance, but retains the characteristic orange-red color from the released hemoglobin. These casts may be distinguished as blood casts, indicating greater stasis WBC CAST The appearance of WBC casts in the urine signifies infection or inflammation within the nephron. They are most frequently associated with pyelonephritis and are a primary marker for distinguishing pyelonephritis (upper UTI) from Cystitis (lower UTI) They are also present in non-bacterial inflammations such as acute interstitial nephritis and may accompany RBC casts in glomerulonephritis WBC casts are visible under low-power magnification but must be positively identified using high power Staining and the use of phase microscopy can be helpful to enhance the nuclear detail needed for differentiating WBC cast from Epithelial cast BACTERIAL CAST Bacterial casts containing bacilli both within and bound to the protein matrix are seen in pyelonephritis. Their presence should be considered when WBC casts and many free WBCs and bacteria are seen in the sediment Confirmation of bacterial casts is best made by performing a Gram stain on the dried or cytocentrifuged sediment. FATTY CAST Fatty casts are seen in conjunction with oval fat bodies and free fat droplets in disorders causing lipiduria. They are most frequently associated with the nephrotic syndrome, but are also seen in toxic tubular necrosis, diabetes mellitus, and crush injuries Confirmation of fatty casts is performed using polarized microscopy and Sudan III or Oil Red O fat stains. GRANULAR CAST Coarsely and finely granular casts are frequently seen in the urinary sediment and may be of pathologic or nonpathologic significance. The origin of the granules in non-pathologic conditions appears to be from the lysosomes excreted by RTE cells during - normal metabolism. Granular casts are easily visualized under low-power microscopy. However, final identification should be performed using high power to determine the presence of a cast matrix. Pathologic increase: Glomerulonephritis and pyelonephritis Physiologic increase: Strenuous exercise WAXY CAST Waxy casts are representative of extreme urine stasis, indicating chronic renal failure. They are brittle, and highly refractive compared to hyaline cast They often appear fragmented with jagged ends and have notches in their sides Ground glass appearance, homogeneous matrix, with cracks or fissures from margins or along the length of the cast With supravital stains, waxy casts stain a homogenous, dark pink Waxy casts are more easily visualized than hyaline casts because of their higher refractive index BROAD CAST Often referred to as renal failure casts Broad casts may result from tubular distension or, in the case of extreme urine stasis, from formation in the collecting ducts The presence of broad casts indicates destruction (widening) of the tubular walls. Also, when the flow of urine to the larger collecting ducts becomes severely compromised, casts form in this area and appear broad. All types of casts may occur in the broad form Bile-stained broad, waxy casts are seen as the result of the tubular necrosis caused by viral hepatitis Two most commonly seen broad cast: granular and waxy GRANULAR DIRTY BROWN CAST Granular, dirty, brown casts representing hemoglobin degradation products such as methemoglobin may also be present They are associated with the acute tubular necrosis often caused by the toxic effects of massive hemoglobinuria that can lead to renal failure. These dirty, brown casts must be present in conjunction with other pathologic findings such as RTE cells and a positive reagent strip test for blood