Factoring the metabolic X syndrome
Metabolic X syndrome is a multisystem disease that requires screening, counseling, assessment, and treatment for a wide variety of metabolic problems.
Although there is debate surrounding the definition of metabolic X syndrome in pediatrics and there are few long-term studies of outcomes in children with metabolic syndrome, pediatric metabolic syndrome needs to be on the radar of all pediatricians interested in ensuring a healthy adult life for their patients.
Cardiovascular disease was nearly 15 times more common among children and adolescents with metabolic syndrome traits in the Lipid Research Clinics study compared with those without the traits. More than two-thirds of patients with metabolic syndrome traits as children went on to develop metabolic syndrome as adults.1 Metabolic syndrome is truly a multisystem disease that requires the pediatrician provide screening, counseling, assessment, and treatment for a wide variety of metabolic problems.
Despite numerous attempts to define metabolic syndrome in the pediatric population, no consensus definition currently exists. There are number of reasons why, including2:
· Some adolescents have transient insulin resistance during adolescence.
· Normal lipid levels vary by age, sex, race.
· There is a lack of standardization for diagnosis of central obesity.
· Metabolic abnormalities in children with metabolic syndrome are relatively moderate.
Whereas different criteria for diagnosing metabolic syndrome exist,3-5 all the definitions generally include assessment and presence of some combination of the following parameters (Table 1 and 2):
1. Elevated triglyceride levels;
2. Reduced high-density lipoprotein (HDL);
3. Elevated blood pressure (BP);
4. Impaired fasting glucose concentration; and
5. Increased waist circumference.
Although the pathogenesis of pediatric metabolic syndrome is not fully elucidated, interactions between insulin resistance, obesity, increased lipids, and inflammation are all involved. Free fatty acid accumulation in hepatic tissue, muscle, and adipose tissue along with lipid partitioning of fat to areas that are more insulin resistant (eg, visceral abdomen) results in limiting insulin sensitivity. Accumulation of free fatty acids in the liver increases both insulin and triglyceride levels. The process also impacts endothelial cell function that further limits sensitivity of tissues to insulin, resulting in decreased uptake of glucose and inflammation. As the body accumulates more fat in adipocytes, an inflammatory response ensues that stimulates more inflammatory activity. Although not fully understood, obesity, inflammation, and insulin resistance are important concepts in the development of pediatric metabolic syndrome.2,5