Metabolic syndrome and uric acid levels - A cross sectional study

 

 

Abstract              Background: Interdependence of Serum Uric Acid (SUA) and Metabolic Syndrome (MeS) is a controversial matter with an increasing prevalence of chronic diseases. Nearly 33% of Indians suffer from metabolic syndrome making it a public health problem due to its sheer prevalence and rate of increase. Methodology: This was a cross sectional study done among 100 patients with metabolic syndrome aged 18-70 during 1 year period in a tertiary care hospital in South India with an aim to find prevalence of hyperuricemia among them. Results: Majority 94 % were females. 90% had history of Diabetes Mellitus (DM) and 63% had history of Hypertension (HTN). Among 100 subjects 42 had hyperuricemia; level of uric acid>7 mg/dl in blood. Hyperuricemia was significantly associated with Diabetes Mellitus and female gender. Conclusion: Association between hyperuricemia and Metabolic Syndrome should be scrutinised further for prevention and early identification of chronic disease.

Key Word: Chronic Disease, Hyperuricemia, Metabolic Syndrome, Uric Acid

 

INTRODUCTION

Metabolic syndrome (MeS) is a complex interaction of insulin resistance and compensatory release of more insulin leading to clustering of obesity (particularly central adiposity), hyperglycaemia, elevated blood pressure, hypertriglyceridemia, and decreased high density-lipoprotein cholesterol (HDL-C).¹ The prevalence of metabolic syndrome is increasing worldwide with an 2.5-fold increase in cardiovascular mortality and a 5-fold higher risk of developing diabetes.^2,4 It is also associated with increased risk of kidney disease and mortality due to all causes.⁵ Serum uric acid ( SUA) is a final enzymatic product of purine metabolism in humans, and it is suggested that hyperuricemia (Serum uric acid level > 7 mg/dl) is an increasing metabolic problem. Hyperuricemia can be classified as primary or secondary depending upon its occurrence as a consequence of another coexisting disease or drug. The dietary intake of purine-rich foods (red meat, seafood, beans) or high fat dairy product/alcohol/sweetened soft drink or under-excretion of uric acid due to renal dysfunction and use of thiazide and loop diuretics or extreme levels of physical activity are the main causes for increased production of SUA.^6,8 Hyperuricemia is associated with an increased risk for not only type 2 diabetes mellitus (T2DM) and hypertension (HTN) but also for dyslipidaemia, metabolic syndrome, atherosclerosis, hyperinsulinemia, gout, chronic kidney disease, congestive heart failure, obesity, coronary artery disease and stroke.⁷ Each of this has been demonstrated to be an independent risk factor for CHD and has synergistic manner to accelerate both non diabetic atherosclerosis and atheroscleropathy associated with metabolic syndrome. In like manner, hyperuricemia, hyperhomocystenemia, ROS, highly sensitive CRP each play an important role in metabolic syndrome.^9,10 Increased number of components of metabolic syndrome and hyperuricemia individually pose as risk factors for various morbidities but their association between each other is not well studied in Indian settings. This study aims to identify the association between hyperuricemia and metabolic syndrome and its trend.

 

MATERIALS AND METHODS

This was a cross sectional study done among 100 patients with metabolic syndrome aged 18-70 during 6 months period in a tertiary care hospital in South India. All the patients were interviewed and physical examination was done. Blood pressure (BP) was measured using an automated sphygmomanometer, with the patient in the sitting position before the blood test. Body mass index (BMI) was calculated as weight (kg) divided by height squared (m²) and BMI >25 kg/m² was considered as overweight and >30 kg/m² as obese. Waist circumference (WC) was measured with the measuring tape positioned midway between the lowest rib and the superior border of the iliac crest while the patient exhaled normally. The blood sample was collected in the morning after an 8–12-hour fast. Levels of glucose, Uric acid, liver enzymes( SGOT,SGPT, Bilirubin( Total and direct)), Albumin, Globulin, Total protein, Total cholesterol (TC), High density lipoprotein cholesterol (HDL-C), Low-density lipoprotein cholesterol (LDL-C), and Triglyceride (TG), Very Low-density lipoprotein cholesterol (VLDL-C), were determined in the hospital laboratory using standard methods. The components that contribute to metabolic syndrome were defined as high BP (≥ 130/85 mmHg), Ttruncal obesity (WC > 90 cm for men, > 80 cm for women), Hypertriglyceridemia (>150mg/dL or 1.7mmol/L), Low HDL-C (<40mg/ dL or 1.0mmol/L for men, < 50mg/ dL or 1.3mmol/L for women) and Hyperglycaemia (fasting blood glucose level ≥ 110 mg/ dL or 6.1 mmol/L).^11,12Demographic data was summarised descriptively. Continuous variables were expressed as mean ± standard deviation. Categorical variables were presented as percentages.

 

RESULTS

Among the 100 subjects, 30(30%) belonged to the age group of 40 to 49 years with a mean age of 49.98 ± 10.16 years. Majority 94 % were females. 90% had history of Diabetes Mellitus (DM) and 63% had history of Hypertension (HTN). Majority 77% were overweight with a Body Mass Index (BMI) between 25- 29.9 kg/m². The mean BMI was 27.94± 2.23 with a minimum of 23 and maximum of 35 kg/m². Among 100 subjects 42 had hyperuricemia; level of uric acid>7 mg/dl in blood. (Table 1) Mean uric acid level was 6.46±1.46 with a minimum of 3.4 and maximum of 9.30. Hyperuricemia is present more among Diabetics than non-diabetic( p value-0.04) among overweight and middle aged patients (40-49 years), but the association was not statistically significant. All patients with hyperuricemia were females and this was statistically significant (p value 0.03 # Fischers exact) - Table 2 The mean FBS, Total Cholesterol, LDL, Triglyceride and total protein values were higher among hyperuricemic patients than patients with normal uric acid levels which is not statistically significant.-Table 3

DISCUSSION

In this study we aim to identify hyperuricemic individuals among patients with Metabolic Syndrome (MeS). 42% of the individuals were hyperuricemic which was more compared to other studies.^13,14 Among 100 subjects 42 had hyperuricemia; level of uric acid>7 mg/dl in blood. Mean uric acid level was 6.46±1.46 with a minimum of 3.4 and maximum of 9.30. This higher prevalence may be due to the fact that all study subjects were suffering from more than one of the components of metabolic syndrome which indirectly affect the uric acid metabolism. We found that higher uric acid levels and metabolic syndrome was mutually dependant but their mechanism remains unclear. Plausible explanations were the reduction of endothelial bioavailability of Nitric oxide by uric acid which results in a reduced blood flow to insulin sensitive tissues, i.e. skeletal muscle, liver, adipose tissue, leading to blockage of the action of insulin.¹⁵ Furthermore, increased insulin reduces urinary uric acid excretion by the effect of insulin on urinary tubules leading to hyperuricemia.¹⁶ All 42 of hyperuricemic patients were females contradictory to other studies^17,18 may be due less number of male patients in the study. The closer association of hyperuricemia in women with metabolic syndrome¹³ may lead to proper assimilation of ailments among them.There was significant difference in serum uric acid levels among diabetics and non-diabetics as hyperglycaemia (> 144 mg/dL) with glucosuria may increase UA excretion, resulting in lower serum Uric Acid.^19-21 Majority of hyperuricemic patients were between the age group of 40-60 year and were overweight which is in sync with the pattern of hyperuricemia.^21-23 Deranged lipid levels in patients with hyperuricemia were noted in the study which makes the theory of interrelation between dyslipidaemia and hyperuricemia stronger.⁷

 

CONCLUSION

Serum Uric Acid (SUA) levels were higher in patients with metabolic syndrome and most of them were hyperuricemic. Significant association of hyperuricemia with diabetics show an emerging comorbidity and risk factor and the role should be probed further. Close association of SUA with metabolic syndrome in women in this study can lead to recognition of metabolic syndrome as a frequent comorbidity of hyperuricemia and vice versa. This helps to take early action to prevent subsequent chronic disease. Regarding high prevalence of overweight individuals as well as the potential link between hyperuricemia and CVD, future studies should be conducted to clarify the role of uric acid in the pathogenesis of Metabolic Syndrome. To confirm an interdependence of changes in the risk factor components of metabolic syndrome and SUA level, a prospective study is needed. Factors affecting Uric Acid, such as alcohol consumption, the use of diuretics, physical activity, and a diet habitually high in purines, were not considered in this study. The sample size was low to come to a finite conclusion and generalization to the population.

 

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