Gout in the elderly. Clinical presentation and treatment

Identification of crystals in synovial fluids and joint tissues

The identification of crystals in synovial fluids and joint tissues is the most rapid and accurate method of diagnosing the common forms of crystal-associated arthritis. Although there are numerous methods available for identifying and characterizing crystals in biologic specimens including x-ray crystallography and Fourier transform infrared spectroscopy, in practice, polarizing light microscopy is used almost exclusively for articular crystals. Unfortunately, problems with reliability and reproducibility undercut the usefulness of this simple procedure. This article highlights recent developments in the field and discusses the importance of identifying synovial fluid crystals, proper handling of specimens, and the appropriate use of available technologies for crystal identification.

Difficult gout and new approaches for control of hyperuricemia in the allopurinol-allergic patient

A major obstacle to the treatment of hyperuricemia in patients allergic to allopurinol is the limited availability of suitable, equally effective, alternative, urate-lowering drugs. Conventional uricosuric drugs, including probenecid and sulfinpyrazone, are recommended for allopurinol- intolerant patients with gout and "underexcretion" hyperuricemia who have normal renal function and no history of nephrolithiasis. Therapeutic options in those in whom traditional uricosuric drugs are contraindicated, ineffective, or poorly tolerated include slow oral desensitization to allopurinol and cautious administration of oxipurinol. Allopurinol desensitization is useful particularly in those who have failed other treatment modalities. If available (as in Europe, South Africa, and Japan), benzbromarone may be tried in patients with gout and mild-to-moderate renal insufficiency. Recombinant urate oxidase can be used in the short-term prophylaxis and treatment of chemotherapy- associated hyperuricemia in patients with lymphoproliferative and myeloproliferative disorders. Hyperuricemia and gout occur with increased frequency in cyclosporine-treated allograft transplant recipients. The management of gout in these patients is complicated by two main factors: cyclosporine-induced renal impairment, and interactions with medications used to preserve the allograft.

Crystal-associated arthritis in the elderly

The understanding of the clinical syndromes of gout and pseudogout, and the role of basic calcium crystals in arthritis has increased since the original descriptions of the involvement of crystals in arthritis. Gout is usually considered an affliction confined to middle aged males but has an increasing prevalence in older populations, with unique and often atypical features. Calcium pyrophosphate dihydrate crystal deposition disease is common in elderly patients. The diagnosis of these common forms of arthritis and the need to individualize therapy in patients with other medical problems remain important clinical challenges to the practicing physician.

Clinical manifestations of gout and their management

Gout is an inflammatory response to deposition of monosodium urate crystals in and around joints. It is primarily a disease of adult men. In acute gout, treatment options include non-steroidal anti-inflammatory drugs (NSAIDs), colchicine and corticosteroids, administered either intra-articularly, orally or parenterally. Asymptomatic hyperuricaemia does not require specific treatment, but should prompt screening for atherosclerosis risk factors, and general lifestyle modification to reduce serum urate levels. Gout presents differently in the elderly. Both women and men are affected, attacks are frequently polyarticular and in the upper limbs, and the gout may be associated with diuretic use, hypertension and renal impairment. In patients with peptic ulcer disease, selective COX-2 inhibitors provide another treatment option. In the presence of renal impairment, allopurinol is the treatment of choice for urate lowering therapy, but doses of allopurinol and colchicine must be adjusted. Urate lowering therapy should only be used if recurrent episodes of gout occur despite aggressive attempts to reverse or control the underlying causes. It should not be introduced or discontinued during an acute episode of gout, and gout prophylaxis (NSAIDs or colchicine) should be prescribed during the introduction of urate lowering therapy.

Pharmacokinetics and pharmacodynamics of allopurinol in elderly and young subjects

AIMS

The prevalence of hyperuricaemia and gout increases with age as does the incidence of adverse effects to allopurinol, the major uric acid lowering drug. The present study was performed to compare the disposition and effects of allopurinol and its active metabolite oxipurinol in elderly and young subjects without major health problems.

METHODS

Ten elderly (age range 71-93 years) and nine young subjects (24-35 years) received an oral dose of 200 mg allopurinol in an open, single dose, cross sectional design. Four of these individuals were additionally dosed with 200 mg allopurinol intravenously. Plasma and urine concentrations of allopurinol, oxipurinol, hypoxanthine, xanthine, and uric acid were measured by h. p.l.c.

RESULTS

Total clearance of allopurinol was not different in elderly (15.7+/-3.8 ml min-1 kg-1, mean+/-s.e. mean) and young subjects (15.7+/-2.1), whereas total clearance of oxipurinol was significantly reduced in the aged (0.24+/-0.03) compared with young controls (0.37+/-0.05) as was the distribution volume of oxipurinol (0.60+/-0.09 and 0.84+/-0.07 l kg-1, respectively). Oxipurinol was eliminated primarily by the kidneys, allopurinol by metabolism. Fractional peroral bioavailability of allopurinol was 0.81+/-0.16 (n=4, two elderly and two young subjects). Although maximal plasma concentrations of oxipurinol were significantly higher in elderly (5. 63+/-0.83 microgram ml-1 ) than in young persons (3.75+/-0.25) as was the area under the oxipurinol plasma concentration-time curve, AUC (260+/-46 and 166+/-23 microgram ml-1 h, respectively), the pharmacodynamic effect of oxipurinol was smaller in elderly than young subjects (time-dependent decrease of plasma uric acid 83+/-30 microgram ml-1 h in elderly compared with 176+/-21 in young controls). Oxipurinol increased the renal clearance of xanthine, suggesting inhibition of tubular xanthine reabsorption by oxipurinol.

CONCLUSIONS

Although allopurinol elimination is not reduced in the aged, that of its active metabolite oxipurinol is because of an age-dependent decline in renal function. Xanthine oxidase inhibition by oxipurinol appears to be reduced in old age. In addition to its uricostatic action, oxipurinol has a xanthinuric effect which is also diminished in the elderly.

A practical approach to gout. Current management of an 'old' disease

Gouty arthritis is the culmination of a number of physiologic mechanisms that ultimately result in deposition of uric acid within joints and soft tissues. Decreased uric acid clearance through the kidney is the most common cause of gout. Tophaceous gout occurs in less than 10% of patients. Acute episodes are treated with NSAIDs or colchicine. Low-dose therapy with these agents can also prevent recurrent attacks. Most patients with gout need long-term treatment with either uricosuric agents or xanthine oxidase inhibitors.