Crystal arthritis Flashcards
What is gout?
heterogeneous group of disease with deposition of monosodium urate (MSU) crystals occurs due to hyperuricemia
how can Gout manifest?
Gouty arthritis, Tophi, Gouty nephropathy, and Uric acid nephrolithiasis (kidney stones)
Whats is Gouty arthritis?
recurrent attacks of severe acute and chronic articular and periarticular inflammation
What is Tophi?
aggregated deposits of MSU in joints, bones, and soft tissues. Commonly in digits of hands and feet, olecranon bursa, extensor surface of forearm, Achilles tendon, and antihelix of ear
What is Gouty nephropathy?
renal interstitial, glomerular, and/or tubular deposition of MSU crystals
What are the stages of Gout?
Asymptomatic hyperuricemia (MSU above 7mg/dL), Acute Gouty arthritis, intercritical gout (asymptomatic intervals between attacks, Chronic Tophaceous Gout (Tophi occurs)
Describe an acute gouty arthritis attack
abrupt onset of an exquisitely painful, warm, red swollen joint often at night or early morning. Typically in MTP joint of great toe (podagra) followed by insteps, ankles, heals, knees, wrists, fingers, and elbows. Early attacks Spontaneously resolve in 3-10 days
T or F: gout is more common in men after the age of 30 than women
TRUE
What other medical conditions are often seen with gout?
alcohol abuse, obesity, insulin resistance syndrome, and hypertension
What 2 dysfuctions canlead to hyperuricemia?
increased production or decreased renal excretion of urate
What can does a 24h urinary excretion of >750mg/24h uric acid tell you in gout?
overproduction of uric acid
What can does a 24h urinary excretion of <750mg/24h uric acid tell you in gout?
underexcretion of uric acid
What is the cause of primary gout in most patients?
underexcretion of uric acid seen in 90% of patients
What is the steady state of uric acid?
urate produced + absorbed = urate excreted by kidney + GI tract
What are the 4 steps to Urinary uric acid excretion?
1) glomerular filtration, 2) pre secretory reabsorption in proximal tuble, 3) secretion back into the tuble, and 4) post secretory reabsorption.
What is the net reabsorption of filtered uric acid?
90%
What does the urate/organic anion exchanger (URAT1) do?
reabsorbs uric acid in exchange for tubular secretions and excretions of unwanted organic acids (lactate, acetoacetate, etc).
What drugs cause decreased renal excretion of uric acid?
nicotinate, pyrazinoate, diuretic and low-dose asprin by activating URAT1
What drugs cause increased renal excretion of uric acid?
probenecid, sulfinpyrazone, metaolite of losartan, and high-dose asprin by inactivating URAT1