18 - Gout Flashcards
Define gout
A group of heterogenous diseases characterized by arthropathy resulting from the deposition of rate crystals in and around the joint
More common in ____
males
Peak incidence after ___ yo
40
Modifiable comorbidities for gout
- hyperuricemia
- hypertension
- obesity
- diabetes
- alcohol consumption (binge)
- high purine intake
- drugs
Non-modifiable comorbidities
- chronic kidney disease
- male gender
- age
- family history (genetics)
_____ and high uric acid levels are risk factors for each other.
hypertension
*another point to note is that the medications used to treat hypertension contribute to decreasing kidneys ability to excrete uric acid thus contributing to hyperuricemia
Risk of ______ may be related to chronic low grade inflammation associated with gouty arthritis and type 2 DM as “inflammasome activation disorders” in which monosodium rate and glucose respectively trigger increased processing of IL-Ib
diabetes
How can hyperuricemia promote renal disease?
bc the deposition of urate crystals in the kidney can cause interstitial inflammation and tubular injury, which impairs renal function.
controlling uric acid levels with rate lowering therapy can slow the progression of CKD
What dietary factors can increase uric acid level?
- high purine diet (meats and shell fish)
- decreased mild product intake
What serum uric acid level defines hyperuricemia?
> 480 umol/L in males
> 420 umol/L in females
Etiology behind hyperuricemia?
- overproduction
- underexcretion
What is uric acid?
- just a waste product
- it has no physiological function
- in many other species uric acid is further broken down (typically cats and dogs don’t develop gout) but in humans we do bc the degradation stops at uric acid
10-20% of patients with gout are due to _______ of uric acid
overproduction
How is overproduction of uric acid defined?
3.5 mol/day uric acid excretion while on a 5 day purine free diet
Possible etiologies of overproduction of uric acid?
- diet
- tissue/cell breakdown
- metabolic derangement
80-90% of patients with gout is due to _______
underexcretion
How is under excretion of uric acid defined?
< 3.5 mol/day uric acid excretion while on a 5 day purine free diet
What are some possible etiologies of under excretion?
Renal abnormalities
67% of uric acid is excreted by the kidneys
Describe the renal excretion of uric acid
- uric acid enters glomerulus
- most of this is reabsorbed
- you get 10% of the initial amount being excreted in the urine
- a lot of movement from uric acid in and out of the kidney
What factors alter renal excretion of uric acid?
- Decreased GFR
- Decreased active secretion of uric acid (salicylate, thiazides, acute alcohol, ketoacidosis, lactic acidosis)
- Increased post-secretory resorption (ex. dehydration, high dose ASA)
- Undefined (hypertension, hyperparathyroidism, cyclosporine)
How does temperature affect solubility of uric acid?
decreased temp = decreased solubility of uric acid
*why it precipitates in toe (cold extremely, distal part of body)
Why can you have high uric acid levels and not develop gout?
- need a joint to be damaged which makes it susceptible to uric acid precipitating at that joint level
- our toe undergoes a tremendous amount of stress and develops damage that we don’t address
What 2 things do you need to develop gout?
1) need high uric acid level
2) need susceptible joint
What is the Symkin hypothesis?
when you lay down, an acute gout attack will present
Describe an acute gouty attack
- Sudden onset of warmth, swelling, erythema, and unbearable joint pain
- 50% of first attacks are in toe only
- 90% will have involvement of toe joint sometime during their disease
- usually severe pain
- systemic symptoms such as fever, chills, malaise
- HAS TO BE SUDDEN
- if pt says their toe joint has been hurting for a few days - not a typical presentation
10% of first acute gouty attack involve how many joints?
2 or more
How long do untreated symptoms last in an acute gouty attack?
3-14 days before spontaneous recovery
List 2 reasons why peripheral joint sites are more common for gouty attacks
- decreased temp
- tend to have more joint damage
Precipitating factors of a gout attack?
- stress or trauma to joint
- binge drinking (high purine content)
- infection
- surgery
- rapid lowering of serum uric acid
- drugs that increase uric acid
About half the time, ppl with gouty attack with have ____ uric acid level
normal
- uric acid in plasma is redistributed into joint (so brings down plasma uric acid level)
- if they have a normal uric acid level at the time of flare, it does not mean that they don’t have gout
What lab data needs to be done in the case of an acute attack?
- uric acid level needs to be drawn
- CrCl and BUN (to measure kidney fcn)
- CBC (abnormal CBC can go along with leukaemia or cancer)
What are inter-critical periods?
Periods between attacks:
- Second attack occurs within 6 months to 2 years
- With subsequent attacks inter critical periods become shorter
- Attacks become polyarticular, more severe, and longer lasting
What are some chronic complications of gout?
- Nephrolithiasis (development of uric acid stones in kidneys)
- Gouty nephropathy (chronic or acute): precipitation of uric acid in kidneys
- Tophi formation (uric acid deposits into many peripheral sites)
_____ is really used to prevent precipitation of uric acid in the kidneys
allopurinol
What is chronic tophaceous gout?
-chronic urate deposits in cartilage, tendons, synovial membranes
Common sites of chronic tophaceous gout?
- toe, fingers, wrists, ears, knees
- achilles tendon
When does chronic tophaceous gout occur?
- when inter critical periods no longer pain free (10 years of acute intermittent gout)
- the chronic accumulation of uric acid in the joint will eventually destroy the joint
50-70% of patients will develop chronic tophaceous gout if ?
hyperuicemic therapy not initiated