Crystals & Casts - Answers

Arlo Guthrie — Mon, 20 Apr 2009 13:37:46 GMT

Current Revision posted to Revision Guide For Student Nurses - Part 2 by Arlo Guthrie on 4/20/2009 1:37:46 PM

ANSWERS

Where are casts formed?
The renal tubules.
What is the main component of casts?
Precipitated proteins (usually albumin).
What are the 4 types of cast?
- Hyaline (transparent, cylindrical).
- Cellular (contain rbcs, wbcs or epithelial cells).
- Granular(degenerate cellular casts).
- Waxy.
Are casts generally found in alkaline or acid urine?
Acidic urine.
Of the casts listed above, which are normally present in urine in small numbers?
Hyaline casts.
What might a large percentage of hyaline casts represent?
- Mild tubular inflammation.
- Pyrexia.
- Poor circulation.
What might the presence of cellular casts in the urine indicate?
Acute renal disease.
What might the presence of granular casts in the urine indicate?
Chronic renal disease; these casts are associated with significant inflammatory change.
Waxy casts are very uncommon. Under what circumstances might they be seen?
- Nephroses.
- Amyloidosis.
Define crystalluria.
The presence of crystals in the urine.
What are crystals made of?
Mineral salts.
From what are uroliths composed?
95% Mineral salts and 5% protein/mucoprotein matrix.
What is urolithiasis?
The presence of urinary calculi. These are composed of crystals and may cause a blockage or damage to the urinary tract.
How could you increase the likelihood of confirming the presence of crystals in a urine sample?
Allow it to stand and cool prior to preparing a slide. In addition Sedistain may enhance visualisation.
What is the most common type of crystal seen in cats?
Struvite; also known as triple phosphate or magnesium ammonium phosphate.
What breed of dog is most commonly predisposed to struvite crystalluria?
The miniature Schnauzer.
Struvite usually forms in alkaline urine. What other type of crystal most commonly forms in this environment?
Calcium oxalate crystals.
What dog breeds are predisposed to ammonium urate crystals?
- Dalmatian.
- British bulldog.
- Yorkshire terrier.
What shape describes ammonium urate crystals?
Thorn apple.
What type of poisoning may result in the formation of calcium oxalate crystals?
Ethylene glycol (anti-freeze) poisoning.
What type of crystal may be in evidence in cases of acute hepatic damage?
Leucine.
It is vital that urine samples are fresh, since crystals may form in urine after collection. State the reasons for this.
- Refrigeration.
- Evaporation.
- Increased pH of urine with time (favouring struvite formation).