Medicine MCQs -7
Which of the following stone formation is promoted by the alkaline urine (pH >7.2) and the presence of ammonia in the urine?
Two conditions must coexist for the formation of struvite calculi. These are (1) alkaline urine (pH >7.2) and (2) the presence of ammonia in the urine.
Struvite stones are also known as triple-phosphate (3 cations associated with 1 anion), infection (or infection-induced), phosphatic, and urease stones.
Urease-positive bacteria increase chances of which of the following stone formation?
Urease-positive bacteria, such as Proteus mirabilis can produce the enzyme urease, which converts urea to ammonia and carbon dioxide.
This increases the urinary pH and promotes struvite stone formation.
Which of the following is the diagnostic method to detect kidney stones?
helical CT scan with 5 millimeters (0.2 in) sections is the diagnostic method to use to detect kidney stones and confirm the diagnosis of kidney stone disease
Adding contrast to the CT scan study may sometimes help clarify a difficult or confusing case but in general, contrast obscures calcific densities and as such, contrast scans are usually only indicated during subsequent evaluation of patients with stones.
The noncontrast CT is the cornerstone of initial radiographic assessment.
If a stone grows to more than ----- millimeters, it can cause blockage of the ureter
Which of the following microorganism is not associated with struvite stone formation in urinary tract.
Struvite stones are formed by urinary tract infection with urease producing bacteria that splits urea to ammonium, and increases urine pH to neutral or alkaline values.
Organisms splitting urea are Proteus, Pseudomonas, Klebsiella, Staphylococcus, and Mycoplasma.
E coli is not associated with struvite stones
Randall's plaque is microscopically a plaque of -
Randall's plaque is microscopically a plaque of calcium deposited in the interstitial tissue of the renal papilla. These plaques are thought to serve as a nidus for urinary stone formation. Large amounts of Randall's plaque are unique to idiopathic calcium oxalate stone formers.
What is the composition of Jackstone calculus?
Jackstone calculi - almost always composed of calcium oxalate dihydrate and consist of a dense central core and radiating spicules.
All of the following true for Struvite stone EXCEPT ?
Struvite readily forms in alkaline conditions.
Potentiated by alkaline urine and high magnesium excretion
Which of the following is most common type of kidney stone?
Calcium oxalate: The most common type of kidney stone
High dietary intake of potassium appears to reduce the risk of stone formation because potassium promotes the urinary excretion of citrate, an inhibitor of calcium crystal formation.
Which of the following is used to differentiate between phleboliths and ureteric stone ?
"rim sign " - rim, ring, or halo of soft tissue visible on CT scans that completely surrounds ureteral stones.
The effect is enhanced by the local inflammation a stone produces in the ureteral wall, with subsequent edema at the site of the calculus.
The rim sign is generally missing or incomplete with phleboliths.