MLPAO Urinalysis and Body Fluids Fundamentals Flashcards
6 cards from real MLPAO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 MLPAO Urinalysis and Body Fluids Fundamentals flashcards as text
What is the significance of finding bacteria and WBCs in urine but a negative nitrite test?
Answer: A UTI caused by a nitrite-negative organism (enterococci, staphylococci) is possible; culture should be performed
Not all uropathogens produce nitrite from nitrate. Gram-positive organisms (enterococci, staphylococci) and some others (Pseudomonas, Acinetobacter) do not produce nitrite reductase. Therefore, a negative nitrite with positive WBCs and bacteria still warrants urine culture. Additionally, urine may not have been in the bladder long enough for nitrite conversion.
Which body fluid analysis is used to differentiate a transudate from an exudate?
Answer: Light's criteria (protein ratio, LDH ratio, and LDH level) applied to pleural fluid
Light's criteria classify pleural effusions as exudates if any one criterion is met: 1) Pleural fluid protein/serum protein >0.5, 2) Pleural fluid LDH/serum LDH >0.6, 3) Pleural fluid LDH >2/3 the upper limit of normal serum LDH. Transudates result from hydrostatic/oncotic pressure imbalance (CHF, cirrhosis), while exudates indicate infection, malignancy, or inflammation.
What is the significance of finding oval fat bodies in urine?
Answer: They indicate nephrotic syndrome with lipiduria
Oval fat bodies are renal tubular epithelial cells or macrophages that have absorbed lipid (cholesterol and triglycerides). They are highly characteristic of nephrotic syndrome, where massive proteinuria is accompanied by hyperlipidemia and lipiduria. Under polarized light, cholesterol in oval fat bodies shows a characteristic Maltese cross pattern.
What is the correct procedure for performing a manual urine microscopic examination?
Answer: Centrifuge 10-12 mL of well-mixed urine, decant supernatant, resuspend sediment, place a drop on a slide with coverslip, and examine at low and high power
Standard procedure: 1) Mix specimen well, 2) Transfer 10-12 mL to a centrifuge tube, 3) Centrifuge at 400 × g for 5 minutes, 4) Decant to approximately 0.5-1 mL, 5) Resuspend sediment, 6) Place a drop on a slide with coverslip, 7) Examine under low power (10×) for casts and scan, then high power (40×) for cells, crystals, and organisms. Standardized systems (e.g., KOVA) improve reproducibility.
What does the presence of ketones in urine indicate?
Answer: Increased fat metabolism, seen in uncontrolled diabetes, starvation, high-protein/low-carb diets, and prolonged vomiting
Ketonuria indicates accelerated fat metabolism as an alternative energy source when glucose is unavailable or cannot be utilized. Causes include diabetic ketoacidosis (most clinically significant), starvation, prolonged fasting, low-carbohydrate diets, prolonged vomiting, and strenuous exercise. The dipstick primarily detects acetoacetate.
What crystal with a hexagonal plate shape found in acidic urine is always pathological?
Answer: Cystine
Cystine crystals are hexagonal, colourless, flat plates found in acidic urine and are ALWAYS pathological. They indicate cystinuria, an inherited disorder of amino acid transport in the renal tubules. Cystine stones are among the most difficult to manage urological conditions. The cyanide-nitroprusside test confirms cystine in urine.