Dietary factors associated with hyperuricemia in adults

Recent advances in management of gout

Incidence and prevalence of gout have markedly increased over the last few decades in keeping with the rise in prevalence of obesity and metabolic syndrome. Until recently, management of gout in patients with associated metabolic syndrome and comorbid illnesses such as renal impairment was difficult because of limited treatment options. However, significant progress has been made in the last few years, with introduction of new treatments such as interleukin-1 antagonists for management of acute gout, and febuxostat and pegloticase for chronic gout. The association of gout with alcohol, dietary purines and fructose ingestion has been confirmed in large prospective studies, thus enabling the clinician to now provide evidence-based advice to patients. Recent efficacy and safety data favour lower over higher doses of colchicine, and oral corticosteroids over non-steroidal anti-inflammatory drugs for patients with acute gout. Local ice therapy might help to differentiate gout from other forms of inflammatory arthritis, and supplementation with vitamin C help to reduce risk of gout. Several other drugs with rational mechanisms of action are in the pipeline, and likely to be introduced over the next few years. A new era has thus begun in the field of gout.

High plasma uric acid concentration: causes and consequences

High plasma uric acid (UA) is a precipitating factor for gout and renal calculi as well as a strong risk factor for Metabolic Syndrome and cardiovascular disease. The main causes for higher plasma UA are either lower excretion, higher synthesis or both. Higher waist circumference and the BMI are associated with higher insulin resistance and leptin production, and both reduce uric acid excretion. The synthesis of fatty acids (tryglicerides) in the liver is associated with the de novo synthesis of purine, accelerating UA production. The role played by diet on hyperuricemia has not yet been fully clarified, but high intake of fructose-rich industrialized food and high alcohol intake (particularly beer) seem to influence uricemia. It is not known whether UA would be a causal factor or an antioxidant protective response. Most authors do not consider the UA as a risk factor, but presenting antioxidant function. UA contributes to > 50% of the antioxidant capacity of the blood. There is still no consensus if UA is a protective or a risk factor, however, it seems that acute elevation is a protective factor, whereas chronic elevation a risk for disease.

Major dietary patterns and risk of asymptomatic hyperuricemia in Chinese adults

In this study, we conducted a case-control study to evaluate the association of major dietary patterns and asymptomatic hyperuricemia taking account of blood lipids in Chinese adults. 187 cases with confirmed asymptomatic hyperuricemia and 187 controls were frequency matched on age, gender and area of residence. We conducted factor analysis using dietary information from a validated food frequency questionnaire to derive dietary patterns. The association between major dietary patterns and asymptomatic hyperuricemia was assessed by logistic regression analysis. Three major dietary patterns were found: 1) "animal products and fried food," 2) "western," 3) "soybean products and fruit." In multivariate analyses the "animal products and fried food" pattern score was associated with an odds ratio (OR) of 2.15 (95% CI, 1.22-3.76) compared with the lowest tertile. The OR for the top tertile of score for "soybean products and fruit" pattern was 0.32 (95% CI, 0.19-0.57) compared with the lowest tertile of "soybean products and fruit" pattern score. The significant association of these two patterns and asymptomatic hyperuricemia persisted after further adjusting for blood lipids. On the other hand, the "western" pattern was not associated with asymptomatic hyperuricemia. We observed a positive relationship between the "animal products and fried food" pattern and asymptomatic hyperuricemia, and a negative relationship between the "soybean products and fruit" pattern and asymptomatic hyperuricemia, independent of blood lipids.

Epidemiology of gout: an update

Gout is the most common inflammatory joint disease in men, characterised by formation of monosodium urate (MSU) crystals in the synovial fluid of joints and in other tissues. The epidemiology of gout provides us with the understanding of the disease distribution and its determinants. In an attempt to update the knowledge on the topic, more recent research reports on the descriptive epidemiology of gout are reviewed in this article. The review describes clinical characteristics and case definitions of gout, including the Rome and New York diagnosis criteria of gout, '1977 American Rheumatism Association (ARA) criteria' and the 10 key propositions of the European League Against Rheumatism (EULAR) recommendations. Gout incidence, prevalence, morbidity and mortality, geographical variation of the disease, relevant risk factors for both the occurrence and outcome of gout and trends of the disease over time are then described. Difficulties in obtaining the information and data reported are also discussed.

Hyperuricemia and associated factors: a cross-sectional study of Japanese-Brazilians

This cross-sectional study aimed to estimate the prevalence of hyperuricemia and associated risk factors among Japanese-Brazilians. We obtained data on demographic, health history, food intake, and laboratory variables. Chi-square and prevalence ratios were used as measures of association. 35.3% of the subjects presented hyperuricemia, which was more frequent in smokers, males, age > 55 years, with co-morbidities, individuals on uric acid-increasing medication, serum creatinine > 1.4mg/dL, high alcohol consumption, and low consumption of milk and dairy products. In the multivariate analysis, the associations remained significant with gender, overweight, central obesity, hypertriglyceridemia, and use of specific drugs. Among males, low intake of saturated fat was associated with hyperuricemia. Individuals with hypertension showed a negative association with dairy product consumption. The high hyperuricemia prevalence suggests that changes in nutritional profile and control of associated co-morbidities could help minimize occurrence of this condition.

Serum urate and its relationship with alcoholic beverage intake in men and women: findings from the Coronary Artery Risk Development in Young Adults (CARDIA) cohort

OBJECTIVE

To investigate if beer, liquor (spirits), wine and total alcohol intakes have different associations with serum urate (SU) concentrations at different ages in a cohort of young men and women.

METHODS

Data from 3123 participants at baseline and follow-up at 20 years were used, with balanced proportions of Caucasians and African Americans. The relationships of SU with categories of beer, liquor, wine and total alcohol intake referent to no intake were examined in sex-specific, cross-sectional analyses.

RESULTS

Mean age (SD) at the beginning of follow-up was 25.1 (3.6) years. Compared with non-drinkers, significant associations between higher SU concentrations and greater beer intake were observed among men and women, with more pronounced and consistent associations for women. An association between greater liquor intake and higher SU concentrations was only seen for men at the year 20 evaluation. Wine intake was not associated with SU in either sex and total alcohol was associated with higher SU concentrations in both men and women. The magnitude of the associations between alcoholic beverages intake and SU was modest (≤0.03 mg/dl/alcoholic beverage serving).

CONCLUSION

An association between higher SU concentrations and greater beer intake was consistent and pronounced among women, but also present in men. Despite the small magnitude of the increases in SU associated with alcohol intake, clinical implications in conditions such as cardiovascular disease and gout in young adults who are moderate and heavy drinkers cannot be ruled out.

Childhood course of renal insufficiency in a family with a uromodulin gene mutation

Mutations in the UMOD gene encoding uromodulin (Tamm-Horsfall glycoprotein) result in the autosomal dominant transmission of progressive renal insufficiency and hypo-uricosuric hyperuricemia leading to gout at an early age. The clinical appearance is characterized by renal insufficiency and gout occurring in the late teenage years, with end-stage kidney disease characteristically developing between 40 and 70 years of age. This report provides a long-term characterization of renal functional decline in three children from one family with a novel UMOD mutation (c.891T>G, p.C297W) who received allopurinol and a low protein diet. While renal functional decline is slow in individuals with UMOD mutations, it may appear early in life and be associated with marked hyperuricemia. Anemia was also noted in this family.

Hyperuricemia and metabolic syndrome: associations with chronic kidney disease

The effects of serum uric acid (SUA) and metabolic syndrome on chronic kidney disease (CKD) remain controversial. This study grouped subjects according to a combination of their uric acid and metabolic syndrome status and investigated the association between these groups and CKD to clarify the relationships of SUA and metabolic syndrome to CKD. This survey analyzed data from 81,799 adults (45,148 men and 36,651 women) who underwent health examinations at Chang Gung Memorial Hospital, in northern Taiwan, from 2000 through 2007. Hyperuricemia was defined as an SUA greater than 7.7 mg/dL in men or greater than 6.6 mg/dL in women. Patients were classified by uric acid-metabolic syndrome status as follows: A = no hyperuricemia and no metabolic syndrome, B = presence of metabolic syndrome but not hyperuricemia, C = presence of hyperuricemia but no metabolic syndrome, and D = presence of both hyperuricemia and metabolic syndrome. Kidney function was assessed in terms of the estimated glomerular filtration rate (eGFR) by using the Modification of Diet in Renal Disease Study equation modified for Chinese. CKD was defined as an eGFR <60 mL/min/1.73 m(2). The prevalences of hyperuricemia, metabolic syndrome, and CKD were 22.8% (26.3% in men and 18.6% in women), 13.5% (15.0% in men and 11.6% in women), and 2.2% (2.1% in men and 2.2% in women), respectively. In men, the age-adjusted odds ratios for CKD, with group A as reference, were 1.95 for group B, 4.86 for group C, and 5.85 for group D. In women, the age-adjusted odds ratios were 1.96 for group B, 6.66 for group C, and 9.01 for group D. Hyperuricemia is strongly associated with CKD, independent of the presence of metabolic syndrome.

Serum uric acid is independently associated with metabolic syndrome in subjects with and without a low estimated glomerular filtration rate

OBJECTIVE

The relationship among serum uric acid (SUA), metabolic syndrome, and chronic kidney disease (CKD) is unclear. We examined whether SUA level is an independent risk factor for chronic kidney disease and whether the association between SUA and metabolic syndrome is affected by kidney function.

METHODS

We analyzed 28,745 subjects (17,478 men, 11,267 women, age 20-49 yrs) who underwent health examinations at this hospital between 2000 and 2007. Hyperuricemia was defined as SUA level > 7.7 mg/dl in men or > 6.6 mg/dl in women. Kidney function was assessed by estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease Study equation modified for Chinese subjects. Impaired renal function with low GFR was defined as eGFR < 90 ml/min/1.73 m(2). The UA-low GFR groups were defined according to the observed combination of hyperuricemia and low GFR: Group A (absence of both hyperuricemia and low GFR); Group B (presence of low GFR but no hyperuricemia); Group C (presence of hyperuricemia but not low GFR); and Group D (presence of both hyperuricemia and low GFR).

RESULTS

The prevalence of hyperuricemia, metabolic syndrome, and impaired kidney function with low GFR was 20.3% (27.6% in men, 8.9% in women), 7.6% (10.6% in men, 3.0% in women), and 9.9% (11.6% in men, 7.1% in women), respectively. The Pearson correlation between SUA and eGFR was only -0.26 (-0.21 in men, -0.22 in women; p < 0.001). In men, the age-adjusted odds ratio (OR) of metabolic syndrome was 1.41 (Group B), 2.45 (Group C), and 2.58 (Group D) in comparison with Group A. In women, the age-adjusted OR of metabolic syndrome was 0.83 (Group B), 5.47 (Group C), and 3.31 (Group D) in comparison with Group A.

CONCLUSION

Hyperuricemia is prevalent in the Taiwan population. Hyperuricemia is only weakly associated with renal function, but is strongly associated with metabolic syndrome with or without a low eGFR.