Pitfalls to watch for in the treatment of gout

Gout is a very common form of arthritis.  It is due to abnormal metabolism of foods that contain purines.  A product of purine metabolism is uric acid.  Either the body produces too much uric acid or uric acid is not excreted (gotten rid of) fast enough.  The end result is an accumulation of uric acid in the body.

The excessive uric acid deposits out in joints, kidneys and other areas. Gouty arthritis is characterized by the sudden onset of severe pain, tenderness, redness, and swelling due to inflammation in the affected joint.

Gout usually affects a single joint, most often the big toe. Other joints that also are affected include the knee, ankle, foot, hand, wrist, and elbow. Attacks often occur in the early morning hours.  They can be triggered by dietary indiscretion, eg. eating foods high in purines (red meat, shellfish, etc.) or drinking alcohol (beer and red wine are the chief offenders).

Gout is more common in men than women.  However, it also tends to occur quite often in postmenopausal women receiving diuretic therapy.  It then becomes a more difficult diagnosis to make since the deposits of uric acid may occur in the hands, mimicking osteoarthritis or rheumatoid arthritis.  Women who develop gout often do not have the acute painful episodes seen in male gout.

Gout, while usually not that difficult to diagnose, is fraught with many potential treatment pitfalls.  These include:

Treating patients without gout but who have asymptomatic serum uric acid elevations. Just because the serum uric acid is elevated doesn’t mean the patient has gout.  It is also not an indication for the patient to receive anti-gout therapy.

Allopurinol is the drug of choice for most patients with gout.  It works by reducing the amount of uric acid produced. However, in patients with abnormal kidney function, the dose of allopurinol needs to be adjusted downward to compensate for the kidney dysfunction.

Allopurinol interacts with a number of different medicines.  Some of these interactions can be potentially serious. It is mandatory to recognize some of the important ones.  For instance, concomitant use of allopurinol and azathioprine (a drug used to treat cancer) leads to a marked elevation of azathioprine levels in the blood. This is potentially life-threatening.

Diet needs to be scrutinized while starting therapy for gout.  High purine foods and alcohol should be avoided.

Patients who are started on allopurinol need to be titrated up slowly with their dose.  They should also receive concomitant low dose colchicines to reduce the likelihood of acute attacks of gout that often occur when a patient starts anti-gout therapy.

One of the chief reasons for “failure of a patient to respond” to therapy is not monitoring the serum uric acid level.  This must be kept below 6 mg/dl in order to achieve optimal benefit. Serum urate levels should be checked at six weeks after initiation of medication, then at 3 monthly intervals. In addition, kidney and liver function as well as a complete blood count should be checked to guard against untoward side-effects from the allopurinol.

Probenecid is another medicine used for gout.  It  works by making a patient urinate out excess uric acid.  It is indicated in patients who already do not excrete a lot of uric acid in the urine.  A 24 hour urine collection for uric acid shouldbe obtained to make sure a patient is not an “overexcreter” if probenecid is being considered.  Otherwise, kidney stones can develop.

Febuxostat is a new gout medication that is expected to be FDA approved soon and will increase treatment options