THE METABOLIC SYNDROME
The metabolic syndrome (syndrome X, insulin resistance syndrome) consists of a constellation of metabolic abnormalities that confer increased risk of cardiovascular disease (CVD) and diabetes mellitus (DM). The criteria for the metabolic syndrome have evolved since the original definition by the World Hea0 Organization in 1998, reflecting growing clinical evidence and analysis by a variety of consensus conferences and professional organizations. The major features of the metabolic syndrome include central obesity, hypertriglyceridemia, low HDL cholesterol, hyperglycemia, and hypertension.
The OF consensus worldwide definition of the metabolic syndrome (2006): Central obesity (defined as waist circumference’ with ethnicity specific values) AND any two- of the following:
• Raised triglycerides: > 150 mg/dL (1.7 mmol/L.), or specific treatment for this lipid abnormality.
• Reduced HDL cholesterol: < 40 mg/dL (1.03 mmol/L) in males, < 50 mg/dL (1.29 mmol/L) in females, or specific treatment for this lipid abnormality • Raised blood pressure: systolic BP > 130 or diastolic BP >85 mm Hg, or treatment of previously diagnosed hypertension.
• Raised fasting plasma glucose :(FPG)>100 mgholL (5.6 mmol/L), or previously diagnosed type 2 diabetes. If FPG >5.6 mmol/L or 100 mg/dL, OGTT Glucose tolerance test is strongly recommended but is not necessary to define presence of the Syndrome.
• If BMI is >30 kg/m2, central obesity can be assumed and waist circumference does not need to be measured
The US National Cholesterol Education Program Adult Treatment Panel III (2001) requires at least three of the following:
• Central obesity: waist circumference 102 cm or 40 inches (male), 88 cm or 36 inches(female)
• Dyslipidemia : TG ≥1.7 mmol/L (150 mg/dI)
• Dyslipidemi : HDL-C 0.90 (male); > 0.85 (female), or body mass index > 30 kg/m2
• Microalbuminuria: urinary albumin excretion ratio20 μg/min oralbumin: creatinine ratio 30 mg/g
The European Group for the Study of Insulin Resistance (1999) requires insulin resistance defined as the top 25% of the fasting insulin values among non-diabetic individuals AND two or more of the following:
• Central obesity: waist circumference 94 cm (male), 80 cm(female)
• Dyslipidemia: TG 2.0 rnrnol/L and/or HDL-C < 1.0 mmol/L or treated for dyslipidemia
• Hypertension: blood pressure 140/90 mmHg or antihypertensive medication
• Fasting plasma glucose 6.1 mmol/L
High-sensitivity C-reactive protein (hs-CRP) has been developed and used as a marker to predict coronary vascular diseases in metabolic syndrome, and it was recently used predictor for non-alcoholic fatty liver disease in correlation with serum markers that indicated lipid and glucose metabolism.
Prevalence of the metabolic syndrome varies across the globe, in part reflecting the worldwide is in Native Americans, with nearly 60% of women ages 45— 49 and age and ethnicity of the populations studied and the diagnostic criteria applied. In general, the prevalence of metabolic syndrome increases with age. The highest recorded prevalence 45% of men ages 45-49 meeting National Cholesterol Education Program, Adult Treatment Panel Ill (NCEP:ATPI II) criteria.
In the United States, metabolic syndrome is less common in African-American men but more common in Mexican-American women. Based on data from the National Health and Nutrition Examination Survey (NHANES), III, the age-adjusted prevalence of the Metabolic syndrome in the United States is 34% for men and 35% for women. In France, a 30-64-year-old cohort shows a <10% prevalence for each gender, although 17.5% are affected in the 60-64 age range. Greater industrialization worldwide is associated with rising rates of obesity, which is anticipated to dramatically increase prevalence of the metabolic syndrome, especially as the population ages. Moreover, the The metabolic syndrome affects 44% of the U.S. population older than age 50. A greater percentage of women older than age 50 have the syndrome than men. The age dependency of the syndrome’s prevalence is seen in most populations around the world. Rising prevalence and severity of obesity in children is initiating features of the metabolic syndrome in a younger population.
Central adiposity is a key feature of the syndrome, reflecting the fact that the syndrome’s prevalence is driven by the strong relationship between waist circumference and increasing adiposity.
Physical inactivity is a predictor of CVD events and related mortality. Many components of the metabolic syndrome are associated with a sedentary lifestyle, including increased adipose tissue (predominantly central); reduced HDL cholesterol; and a trend toward increased triglycerides, blood pressure, and glucose in the genetically susceptible. Compared with individuals who watched television or videos or used their computer 4 h daily have a twofold increased risk of the metabolic syndrome.
DM is included in both the NCEP and International Diabetes Foundation (IDF) definitions of the metabolic syndrome. It is estimated that the large majority (-75%) of patients with type 2 diabetes or impaired glucose tolerance (IGT) have the metabolic syndrome. The presence of the metabolic syndrome in these populations relates to a higher prevalence of CVD compared to patients with type 2 diabetes or IGT without the syndrome.
The approximate prevalence of the metabolic syndrome in patients with coronary heart disease (CHD) is 50%, with a prevalence of 37% in patients with premature coronary artery disease (age 45), particularly in women. With appropriate cardiac rehabilitation and changes in lifestyle (e.g., nutrition, physical activity, weight reduction, and, in some cases, pharmacologic agents), the prevalence of the syndrome can be reduced.
Lipodystrophic disorders in general are associated with the metabolic syndrome. Both genetic.(e.g., Derardinellieip congenital lipodystrophy, Dunnigan familial partial lipodystrophy) and acquired (e g., HIV related lipodystrophy in pit.ients treated with highly active antiretroviral therapy) forms of lipodystrophy may give rise to severe insulin resistance and many of the metabolic syndrome’s components.
CLINICAL RESEARCH PROJECT-VITAMIN D DEFICIENCY IN METABOLIC SYNDROME PATIENTS
About the study –
The prevalence of common obesity has become a public health concern in many countries as phenomenological approaches to the understanding of pathogenesis have failed to achieve any long term effect on prevention or treatment.
There is evidence for a central control mechanism which maintains body-weight to a set-point by the regulation of energy intake and energy expenditure through homoeostatic pathways. It is suggested that common obesity occurs when the set-point is raised and that accumulation of fat mass functions to increase body size. Larger body size confers a survival advantage in the cold ambient temperatures and food scarcity of the winter climate by reducing surface area to volume ratio and by providing an energy store in the form of fat mass. In addition, it is suggested that the phenotypic metabolic and physiological changes observed as the metabolic syndrome, including hypertension and insulin resistance could result from a winter metabolism which increases thermogenic capacity. Common obesity and the metabolic syndrome may therefore result from an anomalous adaptive winter response.
The stimulus for the winter response is proposed to be a fall in vitamin D. The synthesis of vitamin D is dependent is dependent upon the absorption of radiation in the ultraviolet-B range of sunlight. At ground level at mid-latitudes, UV-B radiation falls in the autumn and becomes negligible in winter. It has previously been proposed that vitamin D primitive organisms as a UV-B sensitive photoreceptor of signaling changes in sunlight intensity. It is here proposed that vitamin D is the stimulus for the winter metabolism.It consists of an accumulation of fat mass (obesity) and the induction of a winter metabolism (the metabolic syndrome). Vitamin D deficiency can account for the secular trends in the prevalence of obesity and for individual differences in its onset and severity. It may be possible to reverse the increasing prevalence of obesity by improving vitamin D status.
In accord with this hypothesis, many studies have been done across the globe, most of which have found a negative correlation between vitamin D level and BMI. These studies were done in populations belonging to a particular region. In this context there is scarcity of data on U.S population and no such study could be traced. Present study will provide valuable information regarding relation of vitamin D level with obesity and metabolic syndrome in U.S population.