Rheumatology: Crystal Arthropathies Flashcards
The _____ are a group of diseases characterized by tissue deposition of monosodium urate (MSU) crystals due to hyperuricemia.
crystal arthropathies
Name the 4 manifestations of crystal arthopathies.
- gouty arthritis
- tophi (deposits of MSU)
- gouty nephropathy
- uric acid nephrolithiasis (kidney stones)
____ usually refers to acute or chronic arthritis 2a to MSU crystals.
Gout
Hyperuricemia without symptoms is referred to as _____, not gout.
asymptomatic hyperuricemia
What are the 4 stages of gouty arthritis?
- asymptomatic hyperuricemia
- acute gouty arthritis
- intercritical gout
- chronic tophaceous gout
What are the features of asymptomatic hyperuricemia?
elevated serum uric acid (>7.0mg/dL) w/o gouty arthritis, tophi, or uric acid nephrolithiasis
What are the features of acute gouty arthritis?
- Acute onset of painful, warm, red, swollen joint, especially at night or morning.
- MTP of great toe most common (podagra) but also can be insteps, ankles, heels, knees, wrists, fingers, and elbows.
- Resolves after 3-10 days.
What is intercritical gout?
asymptomatic intervals between acute attacks of gout
What is chronic tophacous gout?
- subcutaneous, synovial, or subchondral bone deposits of MSU crystals
- commonly on digits of hands and feet, olecranon bursa, extensor surface of the forearm, Achilles tendon, or antihelix of the ear
Gout typically occurs in _____, age _____.
men; 30+ (peak incidence 50)
What other conditions are associated with gout?
EtOH abuse
obesity
insulin resistance
hypertension
How is gout definitively diagnosed?
synovial fluid evaluation
In gout, the intracellular crystals in the PMNs are _____-shaped and _____ when parallel to the axis.
needle; yellow
In gout, the synovial fluid is inflammatory (______-_____ leukocytes/mm3) with predominance of ______.
20,000-100,000; neutrophils
Hyperuricemia can result from ______ or _____ of urate.
increased production; decreased renal excretion
The majority of pts (90%) with 1a gout are _____ of uric acid.
underexcretors
Urinary uric acid excretion occurs thru a 4 compartment model:
- glomerular filtration
- pro-secretory filtration
- secretion back into the tubule
- post-secretory reabsorption
Net tubular reabsorption is about ____ of the filtered uric acid, therefore only ____ of the UA is excreted in the urine.
90%; 10%
What is the urate/organic ion exchanger in the proximal tubule?
URAT1
Certain drugs/metabolites decrease the renal excretion of uric acid by activating URAT1, including ____.
nicotinate, pyrazinoate, diuretics, and low-dose aspirin
Certain drugs/metabolites increase the urinary excretion of UA by inhibiting URAT1, including _____.
probenecid, sulfinpyrazone, a metabolite of losartan, and high-dose aspirin
Uric acid is a product of _____ metabolism bc humans lack the enzyme, _____.
purine; uricase
In rare cases, overproduction of UA can be due to superactivity of _____ or deficiencies of ______.
PRPP; HGPRT
Complete deficiency of HGPRT results in ______.
Lesch-Nyhan syndrome
What are the features of Lesch-Nyhan Syndrome?
mental retardation, spasticity, choreoathetosis, and self-mutilation
What factors affect urate solubility?
- temperature (cold)
- dehydration
- trauma
- pH (less soluble at low pH)
Uric acid crystals interact with synovial lining cells leading to the activation of ____ and _____.
monocytes; mast cells
How is acute gout treated/prevented?
weight loss reduction of dietary purines limitation of fructose and EtOH NSAIDs colchicine corticosteroids
How is chronic gout treated?
- uricosuric (probenecid)
- xanthine oxidase inhibitor (allopurinol, febuxostat)
What does CPDD stand for?
calcium pyrophosphate dihydrate deposition disease
CDDD is a type of arthritis associated with the release of ______ crystals into the joint space and chondrocalcinosis.
calcium pyrophosphate dehydrate (CPPD)
_____ is the term used to describe an acute episodic arthritis due to CPPD crystals.
Pseudogout
Psuedogout attacks are characterized by?
sudden onset pain, swelling, warmth, and redness of a large joint, most often the knee
Unlike gout, in pseudogout the ____ joint is rarely involved.
first MTP
CPDD is a disease of the ______, with associations to ____ and _____ disease.
elderly; hyperparathyroidism, hemachromatosis
What are risk factors for CPDD?
osteoarthritis, trauma, surgery
In CPDD, the synovial fluid will have _____-shaped crystals and will be _____ when parallel to the red compensator light.
rhomboid; blue
In CPDD, the synovial fluid will be inflammatory (____-____ leukocytes/mm3) with predominately _____.
2000-80,000; neutrophils
What does PPi stand for?
pyrophosphate
The source of PPi is from the metabolism of ______, particularly from articular chondrocytes.
nucleoside triphosphates (NTP)
What gene can be mutated in CPDD?
ank gene (ANKH)
CPDD crystals do not form spontaneously in the synovium- they are released by the _______ of pre-formed crystals in the cartilage matrix.
“shedding phenomenon”
What is the treatment of CPDD?
anti-inflammatory drugs similar to gout
