Hyperuricemia and gout in renal transplant recipients

Treating Gout in Kidney Transplant Recipients

Objective

To review the etiology, treatment, and preventive strategies of hyperuricemia and gout in kidney transplant recipients.

Data Sources

Primary literature was obtained via Medline (1966-June 2003).

Study Selection and Data Extraction

Studies evaluating treatment and prevention of hyperuricemia and gout in kidney transplantation were considered for evaluation. English-language studies were selected for inclusion.

Data Synthesis

Approximately 14000 kidney transplantations were performed in the United States in 2003, and of those transplant recipients, nearly 13% will experience a new onset of gout. The prevalence of hyperuricemia is even greater. There are several mechanisms by which hyperuricemia and gout develop in kidney transplant recipients. Medication-induced hyperuricemia and renal dysfunction are 2 of the more common mechanisms. Prophylactic and treatment options include allopurinol, colchi cine, corticosteroids, and, if absolutely necessary, nonsteroidal anti-inflammatory drugs.

Conclusion

It is generally recommended to decide whether the risks of prophylactic therapy and treatment outweigh the benefits. Often, the risk of adverse events associated with agents to treat these ailments tends to outweigh the benefits; therefore, treatment is usually reserved for symptomatic episodes of acute gout. Practitioners must also decide if changes in immunosuppressive regimens may be of benefit on a patient-by-patient basis.

Hyperuricemia and gout in solid-organ transplant: update in pharmacological management

Hyperuricemia is a common comorbid condition experienced by up to 28% of kidney transplant recipients. These patients are at elevated risk of acute flare-ups of gout because of transplant-specific risk factors such as impaired renal function, chronic contributing pharmacotherapy (eg, calcineurin inhibitors, diuretics), and associated comorbid conditions. After transplant, treatment is often complicated by drug-drug interactions, renal impairment, and toxic effects of drugs with the use of first-line recommended agents. A number of therapeutic options remain available for transplant recipients, including dose modifications of historic agents and newer pharmacotherapeutic options. Notably, the Kidney Disease Improving Global Outcomes guidelines address the management of hyperuricemia and gout, but these guidelines were last published in 2009, and new data and treatment options have emerged since then. The management of hyperuricemia and acute and chronic gout is described, including the use of novel agents including urate oxidases, interleukin 1 inhibitors, and human urate transporter 1 inhibitors and alternative immunosuppressive therapy strategies.

Prevalence and risk factors of hyperuricemia among kidney transplant recipients

Hyperuricemia is common in renal transplant patients (RTRs), especially those on cyclosporine (CsA)-based therapy. We conducted a retrospective study to determine the prevalence of hyperuricemia and its risk factors among RTRs. A total of 17,686 blood samples were obtained from 4,217 RTRs between April 2008 and January 2011. Hyperuricemia was defined as an uric acid level of ≥7.0 mg/dl in men and of ≥6 mg/dl in women that persisted for at least two consecutive tests. Majority (68.2%) of RTRs were normouricemic. Hyperuricemia was more frequent in younger and female RTRs. On multivariate logistic regression, we found high trough level of cyclosporine to be a risk factor for hyperuricemia. In addition, female gender, impaired renal function, and dyslipidemia (hypercholesterolemia, hypertriglyceridemia, and elevated LDL) were also associated with higher probability of hyperuricemia. Hyperuricemia is a common complication after renal transplantation. Risk factors implicated in post-transplant hyperuricemia include high trough level of cyclosporine, female gender, renal allograft dysfunction, and dyslipidemia.

Effect of cyclosporine on the pharmacokinetics of colchicine in healthy subjects

OBJECTIVE

Colchicine and cyclosporine are often administered together, particularly in patients who have undergone solid-organ transplantation. However, the potential for drug-drug interactions between these agents resulting in colchicine toxicity is high.

METHODS

This study sought to determine the effect of cyclosporine (100-mg capsule) on the pharmacokinetics of the US Food and Drug Administration-approved formulation of colchicine (0.6-mg tablet) after single oral-dose administration in 24 healthy subjects under fasted conditions in a phase 1, single-sequence, 2-period drug-drug interaction trial.

RESULTS

Coadministration of cyclosporine increased colchicine maximum observed plasma concentration, area under the plasma concentration-time curve to the last measurable time point, and area under the plasma concentration-time curve to time infinity on average by 224%, 216%, and 215% (ie, almost doubled), respectively, and decreased colchicine oral clearance on average by 72% (from 48.24 to 13.42 L/h), indicating substantially higher colchicine exposures when combined with cyclosporine, compared with colchicine alone.

CONCLUSION

The dose of colchicine should be reduced by ≥ 50% when colchicine and cyclosporine are administered concurrently for treatment and prophylaxis of gout flares or treatment of patients with familial Mediterranean fever. Health care professionals should be vigilant for potential adverse events during colchicine/cyclosporine coadministration, notably in patients who have undergone solid-organ transplantation.

TRIAL REGISTRATION

www.ClinicalTrials.gov identifier NCT00983931 (http://clinicaltrials.gov/ct2/show/NCT00983931).

Effects of hyperuricemia on renal function of renal transplant recipients: a systematic review and meta-analysis of cohort studies

Background

Hyperuricemia is an independent risk factor of nephropathy, but its role in renal transplant recipients (RTRs) is controversial.

Methods

Based on the methods of Cochrane systematic reviews, we searched MEDLINE (1948–2011.6), EMBASE (1956–2011.6), CBM (Chinese Biomedicine Database) (1978–2011.6) to identify cohort studies assessing the association between uric acid level and kidney allograft. Two authors independently screened the studies, assessed the risk of bias of included studies and extracted data. Unadjusted odds ratio(OR), mean difference (MD), adjusted hazard ratio (aHR) and their corresponding 95%CI were pooled to assess the effects of hyperuricemia on kidney allograft.

Results

Twelve cohort studies were included and the quality was moderate to high based on the NEWCASTLE-OTTAWA quality assessment scale. RTRs with hyperuricemia had lower eGFR (P<0.0001, 95%CI−16.34∼6.14) and higher SCr (P<0.00001, 95%CI 0.17∼0.31) than those with normal uric acid level. Meta-analysis showed that hyperuricemia was a risk factor of chronic allograft nephropathy (Unadjusted OR = 2.85, 95%CI 1.84∼4.38, adjusted HR = 1.65, 95%CI 1.02∼2.65) and graft loss (Unadjusted OR = 2.29, 95%CI 1.55∼3.39; adjusted HR = 2.01, 95%CI 1.39∼2.94).

Conclusions

Current evidence suggests that hyperuricemia may be an independent risk factor of allograft dysfunction. Hyperuricemia may modestly increase the risk of poor outcomes of RTRs. Future research is needed to verify whether lowering uric acid level could improve the kidney function and prognosis of RTRs with hyperuricemia.

Hyperuricemia after renal transplantation

BACKGROUND

Hyperuricemia is a common complication after kidney transplantation, and may adversely affect graft survival.

OBJECTIVE

To assess the prevalence of and predictors for development of hyperuricemia after renal transplantation.

MATERIALS AND METHODS

Hyperuricemia was defined as a serum uric acid concentration of at least 7.0 mg/dL in men and 6.0 mg/dL in women. From March 2008 to May 2010, uric acid concentration was measured in 12,767 blood samples from 2961 adult renal transplant recipients (64% male and 36% female patients).

RESULTS

Hyperuricemia was observed in 1553 patients (52.4%). The disorder frequently occurred in women (P=.003) and in patients with impaired renal graft function (P=.00). After adjustment for sex, serum creatinine concentration, diabetes mellitus, cyclosporine concentration, and dyslipidemia, only female sex (P=.03) and renal allograft dysfunction (P=.05) were associated with hyperuricemia after kidney transplantation.

CONCLUSION

Hyperuricemia is a common complication after kidney transplantation, and renal allograft insufficiency predisposes to higher uric acid concentration.

Epidemiology, risk factors, and lifestyle modifications for gout

Gout affects more than 1% of adults in the USA, and it is the most common form of inflammatory arthritis among men. Accumulating data support an increase in the prevalence of gout that is potentially attributable to recent shifts in diet and lifestyle, improved medical care, and increased longevity. There are both nonmodifiable and modifiable risk factors for hyperuricemia and gout. Nonmodifiable risk factors include age and sex. Gout prevalence increases in direct association with age; the increased longevity of populations in industrialized nations may contribute to a higher prevalence of gout through the disorder's association with aging-related diseases such as metabolic syndrome and hypertension, and treatments for these diseases such as thiazide diuretics for hypertension. Although gout is considered to be primarily a male disease, there is a more equal sex distribution among elderly patients. Modifiable risk factors for gout include obesity, the use of certain medications, high purine intake, and consumption of purine-rich alcoholic beverages. The increasing prevalence of gout worldwide indicates that there is an urgent need for improved efforts to identify patients with hyperuricemia early in the disease process, before the clinical manifestations of gout become apparent.

Influence of cyclosporine and tacrolimus on serum uric acid levels in stable kidney transplant recipients

Although hyperuricemia is a well-known adverse effect of cyclosporine (CsA) treatment, there are contradictory data regarding the effect of tacrolimus on uric acid levels. The aim of this study was to examine the influences of CsA and tacrolimus-based treatment regimens on serum uric acid levels in 155 renal transplant recipients with normal allograft function who underwent renal transplantation between 1999 and 2002. Serum uric acid levels were recorded at 1, 6, 12, 18, and 24 months follow-up. The patients were treated with CsA-based (n = 73), tacrolimus-based (n = 47), or conversion from CsA-based to tacrolimus-based (n = 35) immunosuppressive regimens. Serum uric acid levels for patients in the CsA and tacrolimus groups were 6.3 +/- 1.6 versus 7.9 +/- 1.9 mg/dL and 6.5 +/- 1.8 versus 8.0 +/- 1.8 mg/dL at the study outset and 24 months, respectively. Both of the treatment regimens showed progressively increasing serum uric acid levels (P < .001). Serum uric acid levels of patients with treatment conversion from CsA to tacrolimus were 8.6 +/- 2.8 mg/dL before conversion and 8.1 +/- 1.9 mg/dL after conversion. There was no alteration in serum uric acid levels after the change of treatment (P > .05). These findings indicate that, compared with CsA, tacrolimus offers no advantage for serum uric acid levels in renal transplant recipients.

Hyperuricaemia and preeclampsia: is there a pathogenic link?

OBJECTIVE

A hypothesis, based on animal studies and human observational studies, was developed proposing a direct pathogenic link between hyperuricemia and preeclampsia. Epidemiological characteristics of preeclampsia such as its uniqueness to humans and an increased incidence of preeclampsia in multiple pregnancies, increased body mass index, renal and hypertensive disease all have uric acid as their common denominator. Animal studies have linked hyperuricaemia to hypertensive, cardiovascular and renal disease. The aim of the study was to determine whether lowering the serum uric acid levels in preeclampsia would affect biochemical parameters and hypertensive control.

DESIGN

A randomized, double-blind, placebo controlled study.

SETTING

A tertiary referral center.

POPULATION

Forty women with preeclampsia between 26 and 32 weeks gestation.

INTERVENTION

Probenecid 250 mg twice daily for seven days.

MAIN OUTCOME MEASURES

Renal function and haematological parameters, hypertensive control.

RESULTS

In the Probenecid group, there was a significant drop in the serum uric acid levels. Lower uric acid levels in the Probenecid group had no significant effect on blood pressure. Patients in the Probenecid group had a significantly lower serum creatinine value at the end of the study when compared to patients in the placebo group. Other renal function parameters (creatinine clearance, urea, 24 h urinary protein excretion) did not show any significant difference between the two groups. Platelet count differed between the two groups with the platelet count being significantly higher in the Probenecid group at the end of the study.

CONCLUSION

The significant improvement in the platelet count in the Probenecid group warrants further study.