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87 Cards in this Set

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hyperurecemia
serum uric acid level that is elevated more than 2 std deviations above the poppulaltion mean
upper limit of normal
7mg/dl (uricase mtd)
gout
dz that is characterized by recurrent acute attacks of urate crystal-induced arthritis
- incl tophi
tophi
deposits of monosodium urate in and around the joints and cartilage and in the kidneys as well as uric acid nephrolithiasis
serum uric acid level rises
risk of developing gout inc
gout pts serum uric acid level
> 7mg/dl
uric acid
end product of purine metabolism

-produced from both dietary and endogenous sources
- formation results from the conversion of adenine and guanine moieties of nucleoproteins and nucleotides
xanthine oxidase
catalyzes the rxn that occurs as the final step in the degradation of purines to uric acid
uric acid via kidneys excretion
300-600mg/day

2/3's of total uric acid
uric acid via gi tract excretion
100-300mg/day
bodies total uric acid content
1-1.2g
daily turnover rate of uric acid content
600-800mg
urine ph
1-5
poorly soluble free acid
uric acid
exists as monosoium urate salt
uric acid
primary hyperurecemia and gout
result fr an innate defect in purine metabolism or uric acid excretion
hyperurecemia
result fr uric acid overprodxn, impaired renal clearance of uric acid or combo
enzymatic defect
pt's with hyperurecemia and gout
ex of enzymatic defect
HGPRT
PRPP
HGPRT
hypoxanthine-guanine phosphoribosyltransferase
PRPP
phosphoribosyl-1-pyrophosphate

synthetase excess
classified as overproducers or underexcretors of uric acid
primary hyperurecemia and gout
overproducers
synthesize abnormally large amts of uric acid and excrete excessive amts-more than 800-1000mg daily on an unrestricted diet or more than 600 mg daily on a purine-restricted diet
underexcretors
90% of pts

produce normal or nearly normal amts of uric acid but excrete less than 600 mg daily on a purine restricted diet

-slightly inc miscible urate pool
pathway of uric acid
glomerulus ->proximal convoluted tubule ->distal tubule
proximal tubule
here approx 99% if uric acid is reabsorbed into the bloodstream.
glomerulus
uric acid is filtered and enters proximal tubules
distal tubule
uric acid is secreted

about 75% of the amt secreted is reabsorbed therefore almost all urinary uric acid is excreted at the distal tubule
hematological
assoc with inc nucleic acid turnover and breakdown of uric acid
hematological causes
lymphoproliferative disorders
myeloporliferative disorders
hemolytic anemia
hemoglobinopathies
hyperuricemia
reduced renal clearance of uric acid
asa and other salicylates
inhibit tubular secretion of uric acid at low doses
uricosuria
high doses of asa and other salicylates
inc uric acid conc by enhancing nucleic acid turnover and excretion
cytotoxic drugs
ethambutol and nicotinic acid
inc uric acid conc
cyclosporine
pyrazinamide
levodopa
dec renal urate clearance
ethanol
alters uric acid metabolism by inc uric acid producxn thru an inc in adenine nucleotide catabolism and by suppressing renal uric acid excretion as a result of lactate inhibition of renal tubular uric acid secretion
examples of conditions that may cause hyperuricemia
diabetic ketoacidosis
psoriasis
chronic lead poisoning
gouty arthritis
monosodium urate crystals are deposited in the synovium of involved joints
inflam response to mono-na urate crystals
leads to an attack of acute gouty arthritis
sx of acute gouty arthritis
redness
warmth
tenderness
tophi or tophaceous deposits
deposits of monosodium urate crystals
lead to joint deformity and disability
untreated gout -> tophi
kidney involvement
lead to renal impairment
renal complications of hyperurecemia & gout
acute tubular obstruction
urolithiasis
chronic urate nephropathy
acute tubular obstruction
develop 2ndary to uric acid preceipitation in the collecting tubules and ureters with subsequent blockage and renal failure
urate oxidase (rasburicase)
used in prophylaxis and trmt of hyperurecemia in peds w/ leukemia, lymphoma and solid tumor malignancies who are receiving anticancer therapy
conversion of uric acid to allantoin
5x more soluble in urine than uric acid
urolithiasis
formation of uric acid stones in the urinary tract
contributing factor to urolithiasis
low urine pH
chronic urate nephropathy
urate deposits arise in the renal interstitium
asymptomatic hyperuricemia
elevated serum uric acid level but has no s/s of deposition dz
deposition dz
arthritis
tophi
urolithiasis
acute gouty arthritis
painful arthritic attacks
pathogenesis of acute gouty arthritis
monosodium salts -> articular tissue ->inflam rxn
initial attack
abrupt
night or early am -> synovial fluid reabsorbed

involves a few joints
most common site of initial attack
1st metatarsophalangeal joint
podagra
attack at metatarsophalangeal joint
common serum findings for acute gouty arthritis
leukocytosis
moderately elevated erythrocyte sedimentation rate
pseudogout
calcium pyrophosphate dihydrate crystal dz

septic arthritis
drug trmts
nsaids
indomethacin
naproxen
sulindac
colchicine
methyprednisolone acetate
prednisone
corticotropin
triamcinolone acetonide
colchicine
relieves pain and inflam and ending acute attack
moa colchicine
impairs leukocyte migration to inflammed areas and disrupts urate deposition and the subsequent inflam response
iv colchicine
shld never be given IM or subcutaneously due to tissue irritation
bone marrow depression
colchicine therapy
intracritical gout
symptom free period after 1st attack
inc urate productxn
high purine diet
obesity
alcohol comsumption
high purine diet
all meats
organ meats
seafood
beans
peas
asparagus
prophylaxis of acute gout attack
low doses colchicine
low dose nsaids
urate reducing drug therapy
uricosurics
xanthine oxidase inhibitor
uricosurics
increse renal uric acid excretion
zanthine oxidase inhibitor
reduces uric acid production
probenecid
sulfinpyrazone
uricosurics

preferred for underexcretors
long term uricosuric therapy
reduces teh incidence of gouty arthritis attacks

prevents formation of new tophi

helps resolve existing tophi
uricosuric moa
blk uric acid reabsorption at the proximal convoluted tubule -> inc rate of uric acid excretion
uricosuric indication
reduce hyperurecemia for pt's excreting less than 600mg of uric acid per day
not initiated during an acute gout attack
uricosuric therapy
maintain high fluid intake
during uricosuric therapy to dec renal urate precipitation
greatest potential risk of uricosuric drugs
-formation of uric acid crystals in urine
-deposition of uric acid in the renal tubules, pelvis or ureter causing renal colic or the deterioration of renal fxn
maintain an high alkaline irone volume
take 1 g of sod bicarb 3-4x a day + high intake of fluid -> 2L/day
c/i
urinary tract stones
asa
salicylates
antagonize axn of uricosurics
sulfinpyrazone
reduces platelet adhesiveness
cause bld dyscrasias
allopurinol moa
long acting metabolite, oxypurinol, blk the final steps in uric acid synthesis by inhibiting xanthine oxidase
xanthine oxidase
enzyme that converts xanthine to uric acid -> reduces serum uric acid level while inc renal excretion of more soluble oxypurine precursors-> dec the risk of uric acid stones and nephropathy
allopurinol indicaions
doc for lowering uric acid levels in both underexcretors andoverproducers

preferred urate reducing agt
se of allopurinol
exfoliative dermatitis