Crystalline Arthropathies

Crystalline Arthropathies
Presentation by: Walter Eisenhauer MMSc, PA-C

Gout

* The Disease of Kings, The King of Diseases
o Predominately disease of adult men
o Females spared until postmenopause
o Uric Acid by product of Purine metabolism
o 10% of those with gout overproduce- the remaining 90% are underexcretors
* Urates circulate in plasma mainly in unbound form
o Referred to as urate pool
o Pool increases as Uric acid levels increase
o Excreted by two mechanisms
+ Renal
+ Bacterial oxidation in the gut
* Total Body urate Pool 1200 mg males/600 mg females
o 85% denovo synthesis
o 15% dietary intake of purines
o Purine restricted diet may only decrease serum urate level by 1-1.2 mg/dl
Urate – complete filtration

+ Presecretory tubular resorption 99%
+ Tubular excretion 50%
+ Post secretory resorption 80%
+ Excretion of 10% filtered load (600 mg/day)
+ Additional 1/3 excreted by pancreatic and intestinal juices
* Two Main Classifications
o Overproducers
o Under Excreters
* Overproducers
o 10%
o Primary
+ Idiopathic
+ Enzyme abnormalities in purine metabolism
o Secondary
+ Excessive dietary uptake
+ Myeloproliferative disorders
+ Severe muscle exertion
* Decreased excretion- 90%
o Primary Vs Secondary
+ Primary
# Unidentified defect in tubular secretion ( up to 40 % less)

* Secondary
+ Renal insufficiency
+ Diuretics
+ Low dose ASA
+ Cyclosporine
+ Ethambutol
+ Lead toxicity
+ Saturnine gout due to nephropathy
+ DKA
+ Starvation
+ Ketosis
+ Ethanol
+ Lactic acidosis
+ Predisposing illness- HTN, DM etc
+ Combined ETOH/G6PD deficiency
* Urate Pool substantially enlarged in Gout
o Non Tophaceous- 2-4gm
o Tophaceous 30 gm or more
* Urate solubility
o At physiologic ph 99% as urate not uric acid
o Soluability at 37degrees is 7.0 vs 30 degrees is 4.5 mg/dl
o Intrarticular temp at the knee is 33 degrees- ankle 29 degrees
* Acute Gout clinical features
o Males 4th-6th decade
o Consider enzyme abnormality if before 60
o 38% with normal uric acid
o Monoarticular 85-90%
o Podagra in 50%, ultimately 90%
o Primarily lower extremity joints
o Precipitated by
+ Surgery
+ Trauma
+ Febrile Illness
+ Excessive eating or ETOH consumption
* Systemic symptoms in polyarticular forms
o Fever
o Chills
o Elevated WBC/ESR
* Spontaneous resolution over days to weeks
* Females older, post menopausal
* Intercritical gout
o 7-10% only experience initial attack
o 62% with second attack within 1 year
o Majority with attack within 6-24 months
o Ultimately attacks more frequent and polyarticular

* Tophaceous Gout
o 3-21% develop
o Average 11.6 years after initial episode
o Typically ear, elbows, fingers, Achilles tendons but may appear anywhere
o Synovial tophi can lead to bone erosions
* Transplant Gout
o Primarily related to cyclosporine
o Acute gout often after one year
o Tophaceous gout within 5 years
o 13% decrease in ADL’s secondary to gout
* Renal Manifestations
o Stones presenting manifestation of up to 1/3
o Gouty Nephropathy-inter parenchymal deposits of monosodium urate crystals causing inflammation and scarring
o Acute Uric Acid Nephropathy caused by obstruction of tubules with uric acid crystals

* Diagnosis
o Can not make dx with blood studies
o Demonstrate crystals in synovial fluid
o Presence of tophi
o Presumptive on basis of clinical presentation
o Strongly negative birefringent, needle shaped, often intracellular crystals

* Xray
o Punched out lesions
o Asymmetric nodular soft tissue swelling
o Joint space narrowing- often asymmetric

* Treatment

Pseudogout

* CPPD- Calcium Pyrophosphate Dihydrate
* Chondrocalcinosis when calcium in cartilage
* Mimics presentation of Gout attacks
* Treat with NSAIDS
* Rule out Hyperparathyroidism

Crystalline Arthropathies.ppt