Rheuma Case: 51-year-old Man with R Knee and L Ankle Pain

00:02 Okay, today we're gonna talk about gout and pseudogout.

00:06 Fist off, let's do a case.

00:08 A 51-year old man presents to your office with 5 days of right knee and left ankle pain.

00:14 His past medical history is notable for HIV with undetectable viral load, hypertension, CKD stage III, obesity and gout.

00:24 He was also recently hospitalized for a MRSA cellulitis about 2 weeks ago.

00:29 He denies any recent hiking or gardening and his medications include chlorthalidone, gabapentin and he is also on on some antiretroviral medication for his HIV.

00:40 Initial vitals, a little bit of a temperature 37.8 C, heart rate's 87, blood pressure is okay.

00:48 On exam, he has a hot, swollen right knee and a warm, left, swollen ankle.

00:54 Skin exam is normal.

00:56 His creatinine is 1.6 with a baseline of 1.5, indicative of his stage III kidney disease and his white count's a little elevated at 10.4 Uric acid 7.8 So let's use those 4 important features to try and characterize or draw out some of the important features of the case.

01:13 So, time course, sounds like it's subacute.

01:16 It's been going on for about 5 days.

01:18 Next up, the pattern of joint involvement, well, it's his right knee and his left ankle.

01:23 So, it's asymmetric and since it involves 2 to 4 joints, we would use the term oligoarticular.

01:30 Thirdly, looks like with a hot, swollen knee, the very definition of inflammation, we do have evidence of joint inflammation.

01:38 And lastly, is there systemic involvement? Unclear.

01:42 Temperature of 37.8 maybe suggest low-grade fever but hard to say at this time.

01:48 We'll have to get some blood work.

01:50 Blood work there, at least initially, again, a mild white count but not much else going on.

01:56 So, let's look at our differential diagnoses.

01:59 So the things at this point, in favor of gout is the fact that, hey! he's got a history of gout.

02:04 Uric acid level of 7.8 is important.

02:08 Keep in mind that a uric acid level should be less than 7 and the supersaturation point for uric acid is around 7.

02:16 But many patients can have an elevated uric acid level without any evidence of gout.

02:20 So that's something to keep in mind.

02:22 His recent hospitalization as we'll see later is also relevant.

02:26 In favor of pseudogout, it involves the knee.

02:29 He does have a history of hypertension, we'll talk about that later.

02:32 And the things that are in favor of septic joint, he's immunocompromised with his HIV status even if his CD-4 count is okay.

02:40 He did just have a MRSA cellulitis so we're worried about bacteremia and seeding a joint and thus have a low grade temperature.

02:47 And lastly, in favor of Lyme is the fact that he had an oligoarticular arthritis with a low grade temperature, that's pretty classic presentation for Lyme.

02:56 So at the moment, we kinda have all 4 of these items is on our differential diagosis.