USMLE Forum Archives - USMLE Step 2 CK - Rheumatology
Rheumatology
Youngdoctor - 03-25-07 02:38
An old lady with pain in the knee on examination was found to have meniscal calcification. The aspirate from joint showed positively birefringent crystals. What is the likely composition:
a) urate crystals
b) calcium pyrophosphate dehydrate
c) di calcium pyrophosphate
d) hydroxyapatite
Youngdoctor - 03-25-07 02:38
An old lady with pain in the knee on examination was found to have meniscal calcification. The aspirate from joint showed positively birefringent crystals. What is the likely composition:
a) urate crystals
b) calcium pyrophosphate dehydrate
c) di calcium pyrophosphate
d) hydroxyapatite
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#2
Re: Rheumatology TheOne - 03-25-07 19:18 B..."Birefringent" means: splitting a ray of light in two.
Crystals bend light and become visible in joint fluid when viewed through a microscope with crossed polarizing filters.When a compensator plate is used on the microscope,monosodium urate crystals (Choice A) parallel to the axis of the compensator appear yellow (negatively birefringent) and calcium pyrophosphate dihydrate crystals (Choice B) parallel to the axis of the compensator appear blue (positively birefringent).
#3
Re: Rheumatology ammulufy - 07-05-10 21:56 Its probably peudogout whch is associated wid deposition of calcium pyrophosphate n hydroxyapatite crystals....derfore I go wid d.
#4
Re: Rheumatology babbu5508 - 07-06-10 23:19 This usually asymptomatic condition of the elderly is due to deposition of calcium pyrophosphate dihydrate (CPPD) crystals in large joints, most commonly the knee.
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