Rheumatology Part 1 (Gout)- Paulson (Exam 2) Flashcards
Gout definition?
Recurring attacks of acute arthritis Chronic deforming arthritis
Gout epidemiology/RF?
- Men>women
- Pacific islanders
- Alcohol consumption, esp beer
- Red meat, seafood, fructose
- Obesity
- Meds: thiazide & loop diuretics, low dose ASA
Gout pathophys:
- Hyperuricemia needed (but doesn’t always mean gout)
- Serum urate levels > 6.8mg/dL
- Monosodium urate (MSU) level has to be high enough for crystals to precipitate (causes inflammation in joints)
- Resolution of acute inflammation is mediated by immune mechanisms (even w/o tx)
- Over time, chronic inflammatory process, leads to tophi (deposits of MSU) formation, erosion of bone, joint injury
Gout uric acid balance: Underexcreters v overproducers
Underexcreters (majority):
- Renal insufficiency
- Meds: diuretics (loop/thiazide), ASA, levodopa, ethambutol, pyrazinamide)
- Acidosis (dka, ketogenic diet, lactic acidosis)
- Volume depletion/dehydration
- Lead exposure
Overproducers (minority):
- Inherited defect of metabolism
- Lesch-Nyhan syndrome
- Kelley-Seegmiller syndrome
- Myeloproliferative and lymphoproliferative disorders, polycythemia, carcinoma
- Chronic hemolytic anemias
- Transient hyperuricemia associated with ATP consumption
- strenuous exercise, status epilepticus, MI, sepsis
3 stages of gout?
- Acute gouty arthritis 2. Intercritical (interval) gout 3. Chronic articular and tophaceous (MSU crystals) gout
Acute gouty arthritis sx?
- “My big toe hurts”
- Sudden onset, often at night
- Severly painful and tender, swollen joint, red, warm
- May complain of fever
- Reaches maximal severity in about 12-24hrs
- May have hx of similar attacks prior
Seen on acute gouty arthritis exam?
- Swollen, very tender, red, warm overlying skin
- May see desquamation
- May see tophi
-
MTP of great toe is classic sign “podagra”
- usually monoarticular and in the lower extremity
- polyarticular is possible
What is tophi?
- Irregular, asymmetric, macroscopic deposits of urate
- Pathognomonic for gout
- Common sites include external ear, hands, olecranon, feet, knee, achilles tendon, forearm
- Usually painless but can become acutely inflamed Usually develop after years
- Maintain state of inflammation
- promote tissue and joint destruction around them
Gout renal manifestations?
- Uric acid nephrolithiasis (kidney stones)
- Chronic urate nephropathy
- __MSU crystals are deposited in the renal medulla and pyramids
- Uric acid nephropathy
-
ARF (acute renal failure) when large amounts of uric acid crystals precipitate in the collecting ducts and ureters
- usually seen as part of tumor lysis syndrome
-
ARF (acute renal failure) when large amounts of uric acid crystals precipitate in the collecting ducts and ureters
Gout diagnosis?
- Aspirate of synovial fluid showing monosodium urate (MSU) crystals
- “negatively birefringent”, needle-like, when viewed with polarized light microscopy
- US: hyperchoic linear density (double contour sign) over the joint cartilage or deposits that look like tophi
- Radiographs: “rat bite” lesions later in disease process (if next to a tophus=gout)
What labs would you order for suspected gout?
- Serum uric acid (can be normal or low, though)
- Peripheral WBC can be high
- ESR/CRP can be elevated
How many criteria needed to make clinical dx?
>6 Or MSU crystals in joint fluid or tophus
Gout tx?
- If asymptomatic hyperuricemia: don’t treat
- Lifestyle mods:
- lose wt
- reduce etoh
- reduce purine-rich food consumption
- drink lots of water
- Avoid hyperuricemic meds, if possible
Tx of acute gout attack?
- Goal is to relieve pt’s pain
- Start tx asap
- Urate-lowering meds (allopurinol) : don’t help in acute attacks so don’t start one
Gout tx contraindications for NSAIDs
CKD with CrCl< 60, active ulcer, NSAID allergy, concurrent use of anticoagulant, CV disease (esp uncontrolled CHF or HTN)
3 types of Gout meds for acute attack?
NSAIDs 1st choice
- naproxen (Aleve)
- indomethacin
- Discontinue 1-2 days after complete clinical resolution. (Typical course might be 5-7 days)
Colchicine:
- good for pts w/ nsaid intolerance
- commonly causes diarrhea and abd cramping
- possible reversible peripheral neuropathy
- Contraindications: severe hepatic or renal impairment with colchicine use in past 2 wks, concomitant use of a mod-strong inhibitor of P-gp and/or CYP3A4 inhibitor (antifungals, antivirals, some antiarrhythmics)
Corticosteroids:
- good for people who can’t take nsaids or colchicine
- intra-articular injection: triamcinolone
- oral prednisone
- IV methylprednisolone
- IM triamcinolone
- Caution for pts with CHF, glucose intolerance, poor control of HTN
How do we prevent gout?
- Adress preventative issues during the intercritical period
- Goal is to achieve a serum urate level <6mg/dL
- Slowly (not > 1-2mg/dL/month)
- use low-dose prophylactic colchicine (or low-dose NSAID) when initiating antihyperuricemic therapy to reduce risk for acute flare
Meds for chronic gout?
Xanthine Oxidase Inhibitors (XOI) - reduce production of uric acid
- Allopurinol OR Febuxostat
- Give prophylactic colchicine when initiating
Uricosuric meds?
-
Block tubular reabsorption of urate and increases the rate that uric acid is renally excreted
- Pt must have nl renal function
- Probenecid
- Do not give to a pt with G6PD (increases risk of hemolysis)
Uricase med for gout?
- Enzyme present in other mammals that breaks urate down to allantoin, which is more easily excreted
- For pts who have been refractory to all other therapies
- Pegloticase: given IV q 2 weeks
- Don’t give to people with G6PD
Gout prognosis/referral?
- Acute attack will self-resolve even w/o tx
- Over time attacks become more frequent and longer
- W/ urate lowering meds (XO allopurinol or uricase Pegloticase), much less chronic gouty arthritis, tophi, and deformity
- Can refer to rheumatology
How is pseudogout different from gout?
- Gout is urate crystal (needle-like) deposition in joints, while pseudogout is calcium pyrophospate dihydrate (CPPD) crystal (rhomboids) deposition, which can mimic gout.
- Gout usually effects the great toe, while CPPD or pseudogout usually effects larger joints such as the knee.
What is a sign of CPPD pseudogout seen on plain film radiographs?
Chondrocalcinosis: which look like white deposits in the joint space.
What does the typical CPPD pseudogout pt look like?
- Older adults (rare before 55)
- Around 50% of those >85 are affected
- Joint trauma
- Familial chondrocalcinosis
- Hemochromatosis