NBME 24 Monosodium urate (NBME Answers)

NBME 24 Answers ↦

nbme24/Block 2/Question#27 (32.5 difficulty score)
A 47-year-old man comes to the physician ...
Monosodium urate🔍,📺
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+7
submitted by neonem(578),

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hseTe ear gtou sstaclry. I pusepos eth sbte ywa ot itrtfeneefdia isth caes form otpgusoedu is hatt hte tyarlscs rae haspr &am;p edsdpaelne-he and nto mbd.o-heiaphsrod

sympathetikey Yep. They tried to throw you off with the picture, but the wording in the stem says its a "photomicrograph" -- not exposed to plane polarized light, where you would see the negative birefringence. +18

linwanrun1357 Why is NBME so mean to us. Do those mean a lot in clinic？ +

suckitnbme @linwanrun1357 I highly doubt you would be looking at your own joint fluid aspirates instead of sending it to the lab. +3

nnp what those yellow white nodules signify? +

peqmd In clinic gout is typically a clinical diagnosis. If you can treat w/ NSAIDs instead of aspirate you would do that. You would aspirate if you are considering septic arthritis so you can get culture. I don't think anyone aspirate for heck of it. +

lowyield @nnp, the yellow white nodules are tophus which is a sign of chronic gout, characterized histologically by aggregates of uric acid crystals, can show up as skin nodules most commonly on external ear, olecranon bursa or achilles tendon (pg 467 FA 2020) +

+2
submitted by abhishek021196(79),

Calcium Pyrophosphate [Pseudogout] Crystals are rhomboid and weakly ⊕ birefringent under polarized light (blue when parallel to light).

Gout [Monosodium urate] Crystals are needle shaped and ⊝ birefringent under polarized light (yellow under parallel light, blue under perpendicular light

jj375 https://i.pinimg.com/originals/f3/4f/e8/f34fe895aaa93a554469bf6a51cba428.jpg +

+0
submitted by mtkilimanjaro(12),

Also to note: Uric acid KIDNEY STONES are rhomboid not needle shaped. I was dumb and thought gout crystals in synovial fluid were rhomboid and forgot about needle shape :(