Sediment and Microscopic Discussion Flashcards
Pyelonephritis Macroscopic and Microscopic
Macroscopically-cloudy urine, protein, blood, nitrites, leukocyte esterase Microscopically-WBCs, renal epithelial cells, WBC casts, moderate bacteria
Discuss the presence of WBCs in urine sediment including appearance, other cells that may be confused with, and clinical correlation of disease. Average size:
12 um in diameter. Predominant cell see is the neutrophil. Neutrophils exposed to hyptonic urine absorb water and swell. Brownian movement of the granules within these larger cells produces a sparkling appearance, and they are referred to as “glitter cells.”
Discuss the presence of WBCs in urine sediment including appearance, other cells that may be confused with, and clinical correlation of disease. Eosinophils:
Primarily associated with drug-induced interstitial nephritis; however small number of eosinophils may be seen with UTI and renal transplant rejection. Since not commonly found in urine >1% is considered significant
Discuss the presence of WBCs in urine sediment including appearance, other cells that may be confused with, and clinical correlation of disease Mononuclear cells
Lymphocytes may be confused with RBCs. Monocytes, Macrophages, and histiocytes may appear vacuolated or containing inclusions. An increase of WBCs in the urine is called pyuria
Describe general cast composition
Major constituent of a cast is Tamm-Horsfall protein. Tamm-Horsfall protein is a protein secreted by RTE cells of the distal convoluted tubules and upper collecting duct. The rate of excretion appears to increase under conditions of stress and exercise. Protein gels more readily under conditions of urine-flow stasis, acidity, and presence of sodium and calcium
Describe general cast formation
urinary flow within the tubule decreases due to a blocked lumen. Cast width is dependent on the tubule size in which it was formed. Formation of casts at the junction of the ascending loop of Henle and the distal convoluted tubule may produce a structures with a tapered end.
Hyaline
Little significance Dehydration, strenuous exercise, heat exposure, and emotional stress. Most common. Increased in acute glomerulonephritis, pyelonephritis, chronic renal disease, and congestive heart failure.
RBC / True blood / hemoglobin
Shows bleeding within the nephron. Associated with glomerular damage and usually associated with proteinuria and dysmorphic RBCs
WBC casts
Signifies infection or inflammation within the nephron. Most frequently associated with pyelonephritis. Primary maker for distinguishing pyelonephritis (upper UTI) from lower UTIs.
Epithelical Cells
If they contain RTE’s it represents the presence of advanced tubular destruction causing urinary stasis along with disruption of the tubular linings.
Granular (coarse & fine)
Healthy patient and renal disease
Waxy casts
Representative of extreme urine stasis, indicating chronic renal
Fatty casts
Seen in conjuction with oval fat bodies and free fat droplets in disorders causing lipiduria. Most frequently associated with the nephritic syndrome
Broad casts
Represents extreme urinary stasis. Most commonly seen are granular and waxy. May see bile stained with viral hepatitis
Sediment stains:
increases the overall visibility of sediment elements being examined using bright field microscopy. Most common stain is: Sternheimer-Malbin stain: which consists of crystal violet and safranin O. Dye is absorbed well by WBCs, epithelial cells, and casts. Toluidine blue stain (0.5 %) is a metachromatic stain that provides enhancement of nuclear detail. Can be used to differentiation between WBCs and renal tubular cells.
Discuss sediment examination using gram stains and Hansel stain
Gram Stain: Used primary for microbiological examination.
Hansel stain: Polynuclear WBCs usually in urine are neutrophils. Used to confirm presence of eosinophil’s caused by drug-induced allergic reaction producing inflammation of the renal interstitium. Stain consists of methylene blue and eosin Y.
Nephrotic syndrome
Macroscopically and Microscopically:
Macroscopically: cloudy/foamy urine, large amount of protein, small amount of blood
Microscopically: renal cells and casts, granular, waxy, fatty casts, oval fat bodies, urinary fat droplets, renal tubular epithelial cells, epithelial, fatty, and waxy casts, and microscopic hematuria.
Discuss both polarizing microscopy and the Sudan III stain and how they are used to aid in the identification of urine sediment.
Polarizing microscopy: ID of crystals and lipids. Used when sediment demonstrates birefringence which is the ability to refract light in two dimensions at 90 degrees. Used to confirm the identification of fat droplets, oval fat bodies, and fatty casts that produce a characteristic Maltese cross formation.
Lipid Stains: Oil Red O and Sudan III – can be used to confirm the presence of free fat droplets and lipid-containing cells, and casts in urinary sediment.
Describe Oval Fat Bodies
Illustrate
Origin
Significance
Illustrate: Appear highly retractile, and the nucleus may be difficult to observe.
Origin: RTE + absorbed lipids
Significance: Most commonly associated with damage to the glomerulus caused by the nephritic syndrome. Also seen with severe tubular necrosis, diabetes mellitus, and in trauma cases that cause release of bone marrow fat from long bones
Compare and contrast how cholesterol crystals, triglycerides, oval fat bodies and fatty casts look under polarized microscopy
Oval fat bodies -Maltese cross
cholesterol crystals- Rainbow squares and rectangles with notched corners.
Triglycerides- Invisible
Compare and contrast how cholesterol and triglycerides look when stained with Sudan III
Cholesterol will not stain
Triglycerides will stain red or orange
What artifacts can be mistaken for polarizing fat:
Talc crystals
Oils from creams or lubricants
