Review
Am Heart Hosp J. 2011;9(1):28–32
Biomarkers Associated with Cardiometabolic Risk in Obesity
Sidra Younus, MD1 and George Rodgers, MD2
Background: The US is facing an obesity epidemic. Recognizing the biomarkers associated with adipose tissue may impact physicians’ management of cardiometabolic disease greatly. Evidence of acquisition: We searched PubMed for keywords ‘obesity’, ‘leptin’, and ‘adiponectin’, reviewed national surveys, and searched reference articles used in review articles retrieved via the PubMed search. We included articles with multiple relevant citations. Observational data acquired from two sources, not previously published, were also used to support our conclusion. Results: Literature review and analysis of observational data showed that the level of leptin increases with the increase in weight gain, while adiponectin decreases. The roles of these adipokines in the body have been defined. With the increase in leptin levels, the incidence and prevalence of the components of the metabolic syndrome were seen to be higher, resulting in higher cardiovascular disease, while adiponectin was seen to play a more protective role in the body against developing such disease. Conclusions: Measuring circulating levels of leptin and adiponectin as a screening tool may help recognize those individuals who do not only have obesity as a major risk factor toward developing cardiometabolic disease but also may have an unfavorable ‘biomarker profile’, putting them at highest risk. This may encourage the mobilization of resources to help these individuals lose weight rapidly with possibly aggressive measures such as bariatric surgery. Keywords: Obesity, biomarkers, cardiometabolic risk, adiponectin, leptin
besity is an epidemic in the US today. It is now recognized as America’s greatest health risk— according to the Centers for Disease Control and Prevention (CDC), 34 % of the US population is obese (body mass index [BMI] >30). It is critically important to better understand obesity and how it affects cardiovascular health.
O
Figure 1 demonstrates the obesity trends among the US population from the Behavior Risk Factor Surveillance System (BRFSS) in 1990 and 2007.1
Fat cells (adipocytes) lie at the center of obesity. The traditional view has been that these adipocytes are merely fat storage depots. The new paradigm is that the adipose tissue acts as an endocrine organ with its own unique hormones. However, unlike other endocrine tissues, adipose tissue has the potential for limitless growth. The magnitude of its hormonal effects is similarly unlimited.
Adipose Tissue as an Endocrine Organ Multiple studies have been undertaken to investigate the different fat hormones or ‘adipokines’ released from
• University Medical Center Brackenridge,1 28 UT Southwestern Medical School2
the adipocyte and the effects they may have on different components of the ‘metabolic syndrome.’2,3 syndrome is defined in the US as:
The metabolic
• waist circumference >40 inches for men; >35 inches for women;
• fasting blood glucose >100 mg/dl (three measurements); • high-density lipoprotein (HDL) <40 mg/dl for men; <50 mg/dl for women;
• triglycerides >150 mg/dl; and • blood pressure >140/90 mmg (three measurements).
Insulin resistance, lipid metabolism (especially the well-recognized pattern of low HDL, high triglycerides, and small, dense low-density lipoprotein (LDL) particles), and blood pressure are affected by these hormones. Abdominal obesity appears to be the biggest driver of these important adipokines and thus abdominal girth becomes an important parameter in the metabolic syndrome. There is growing evidence that each of the components of the metabolic syndrome is independently atherogenic. Most patients with this syndrome exhibit resistance to
Biomarkers Associated with Cardiometabolic Risk in Obesity
Summer 2011
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