Page 476 - Concise Pathology for Exam Preparation ( PDFDrive )

16 Diseases of the Kidney and Lower Urinary Tract 461

2. Systemic disorders: Blood disorders and collagen diseases
3. Drugs: Salicylates, cyclophosphamide and anticoagulants
WBCs
• More than 20/HPF abnormal
• More than 30/HPF indicative of acute infection
• Adding 2% acetic acid yields better nuclear morphology
• Presence of leukocyte casts is suggestive of renal infection or involvement.
Epithelial Cells
Squamous, transitional and round cells may be seen in the urinary sediment.

Casts
Casts are cylindrical structures with rounded edges composed of Tamm–Horsfall protein
secreted by tubular cells. They usually appear in the urine in renal diseases.
• Hyaline casts are the most frequently occurring casts in urine. Hyaline casts can be seen
in even the mildest renal disease. They are colourless, homogeneous, transparent and
usually have rounded ends. Up to 0–2/low power field are considered normal.
• Red cell casts indicate renal haematuria. Red cell casts may appear brown to almost
colourless and are usually diagnostic of glomerular disease.
• White cell casts are present in renal infection (pyelonephritis) and in noninfectious
inflammation. The majority of white cells that appear in casts are neutrophils.
• Granular casts almost always indicate significant renal disease. However, granular casts
may be present in the urine for a short time following strenuous exercise. Granular casts
that contain fine granules may appear grey or pale yellow in colour. Granular casts that
contain larger coarse granules are darker. These casts often appear black because of the
density of the granules.
• Epithelial casts are rarely seen in urine because the renal disease that primarily affects
the tubules is infrequent.
• Waxy casts result from the degeneration of granular casts. Waxy casts have been found in
patients with severe chronic renal failure, malignant hypertension and diabetic disease of
the kidney. Waxy casts appear yellow, grey or colourless. They frequently occur as short,
broad casts, with blunt or broken ends and often have cracked or serrated edges.
• Fatty casts are seen when there is fatty degeneration of the tubular epithelium, as in
degenerative tubular disease. Fatty casts also result from nephrotic syndrome, lupus and
toxic renal poisoning.

Q. Write briefly on Bence Jones proteinuria.
Ans. Bence Jones proteins are dimers of immunoglobulin light chains, normally produced
by plasma cells.
• They are sufficiently small to be excreted by the kidney and are characteristically found in the
urine of most patients with multiple myeloma, macroglobulinaemias and amyloidosis.
They are used for diagnosis of the disease as well as for monitoring the response to treatment.
• Persistent Bence Jones proteinuria may eventually result in renal failure by two mechanisms:
• Direct toxicity to epithelial cells
• Cast nephropathy (combination of Bence–Jones proteins with Tamm–Horsfall protein
under acidic conditions may form large tubular casts, which obstruct the lumen and
also induce peritubular inflammatory reaction)
• Bence–Jones proteins are detected by:
• Heat coagulation test
• Immunoelectrophoresis, which is a more sensitive method and detects even minute
quantity of the protein

Q. Enumerate renal function tests.
Ans. Renal function tests include
1. Urine examination
(a) Physical and chemical examination

mebooksfree.com