DEFINITION PULMONARY COMPLICATIONS OF OBESITY GENERAL ALTERATIONS IN PULMONARY FUNCTION

The findings of impaired pulmonary function in overweight children highlight an important concern
that decreased lung capacity leads to decreased exercise capacity, followed by decrease in physical
activities, leading to a vicious cycle of impaired lifestyle and overweight. Li et al. found reduction
in functional residual capacity and diffusion impairment were the most common abnormalities in
a cohort of obese patients. Reduction in static lung volume was correlated with the degree of obesity
[33]. Lazarus et al., in a randomized population sample of 2500 Australian adolescents, found
decreased pulmonary function with increasing adiposity [34]. Because the fall in pulmonary function
was severe in obese boys and these falls were correlated with body mass index and skinfolds,
it is concluded that diagnosis and management may improve aerobic exercise performance and
participation in obese children.

DEFINITION HEPATIC STEATOSIS (FATTY LIVER)

Interest in hepatic disorders in obesity has increased as the epidemic of obesity has progressed. As
the patients are usually asymptomatic, liver abnormalities are found on routine blood tests of liver
enzymes. The concern is that the excess fat storage within the liver will lead to chronic inflammation
and eventual cirrhosis, fibrosis, end-stage liver disease, and hepatic failure. The early stage of this
problem, known as nonalcoholic fatty liver disease, is associated with the degree of obesity,
hypertriglyceridemia, and insulin resistance. It is diagnosed on imaging studies such as ultrasound
or computed tomography by evidence of fatty infiltration. Hepatic steatosis is thought to occur
initially, through hepatic and peripheral insulin resistance, which leads to altered glucose and free
fatty acid metabolism. As much as 77% of pediatric referrals for obesity may have evidence of
nonalcoholic fatty liver disease [32]. When the disease progresses, serum chemistries, particularly
alanine aminotransferase (ALT) and aspartate aminotransferase (AST), become elevated, showing
evidence of inflammation, and the condition becomes known as nonalcoholic steatohepatitis, which
has been reported in 5 to 10% of pediatric obesity referrals. The progression, prognosis, and
treatment of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis are under active
investigation. The work-up for nonalcoholic steatohepatitis should include antibody studies to rule
out infectious causes of hepatitis, and enzymes should be monitored during weight management.
Drug usage to treat insulin resistance and antioxidant vitamins to reduce inflammation are areas
of active investigation.

DEFINITION CHOLELITHIASIS (GALLSTONES)

GASTROINTESTINAL SYSTEM
CHOLELITHIASIS (GALLSTONES)
Obesity is a major risk factor for the formation of gallstones, cholecystitis, and cholecystectomy.
Any obese child with classic symptoms of right upper quadrant abdominal pain with or without
fever, nausea, and vomiting should be carefully evaluated and surgical consultation sought. It is
seen mostly in females (70%) and after age 10 years. Cholelithiasis can also be seen following
rapid weight loss, particularly on very low calorie diets, as a result of lack of motility of the
gallbladder. This can be avoided if sufficient fat is included in the dietary regimen [31].

DEFINITION TYPE 2 DIABETES MELLITUS

Type 2 diabetes mellitus, a disease not previously seen in pediatrics, is now recognized as a major
concern. It has become common in pediatric diabetes programs in the last decade [30]. The
prevalence of this disease is a result of the epidemic of severe obesity and presents a major ongoing
challenge to the health care system. It is of so recent an onset that long-term follow-up studies are
not available to determine outcome, but most experts are fearful that complications of this epidemic
will be formidable. Although routine screening of all overweight children is not indicated, the
American Academy of Pediatrics and the American Diabetes Association have guidlines for screening
those age 10 years and above who are at high risk by virtue of being overweight and having
at least two of the following three findings: family history of diabetes mellitus, signs of insulin
resistance, or certain ethnic backgrounds (Native American, African American, Asian-Pacific
Islander, Hispanic). The recommended screening test is a fasting glucose or an oral 2-hour glucose
tolerance test.

DEFINITION POLYCYSTIC OVARIAN SYNDROME

Polycystic ovarian syndrome consists of hyperinsulinemic hyperandrogenism with anovulation. It
is strongly associated with abdominal adiposity, oligomenorrhea, hirsutism, and infertility. These
young women can have psychological effects from the constellation of symptoms and signs that
often begin during adolescence, when body image concerns are paramount [28]. Risk for diabetes,
glucose intolerance, hyperlipidemia, endometrial cancer, infertility, and coronary heart disease are
also elevated. One recent study indicates that some young girls at increased risk may be identified
and prophylactically treated with insulin-sensitizing agents to prevent polycystic ovarian syndrome.
The significant risk factors identified were low birth weight and precocious puberty [29].

DEFINITION METABOLIC SYNDROME OR SYNDROME X

The Adult Treatment Panel III ([25]) has recently defined the metabolic syndrome (or syndrome X,
originally described by Reaven, three decades ago) as having three or more of the following five
factors: high BMI (males > 29 kg/m2, females > 25 kg/m2), high glucose (>110 mg/dL), high
triglycerides (>150 mg/dL), low high-density lipoprotein cholesterol (males < 40 mg/dL, females
< 50 mg/dL), or hypertension (blood pressure > 130/85 mmHg). The importance of diagnosing
this syndrome is that it confers a significant burden of cardiovascular disease risk and, for many
individuals, is a precursor to type 2 diabetes mellitus.
In a study of 439 obese adolescents, Weiss et al. used three out of the following five items as
criteria to diagnose metabolic syndrome: BMI greater than 97th percentile for age and sex, triglycerides
greater than 95th percentile, high-density lipoprotein cholesterol below the 5th percentile,
systolic or diastolic blood pressure above the 95th percentile, and impaired glucose tolerance. By
these criteria, the researchers found metabolic syndrome in 39% of moderately obese adolescents
(BMI > 95th percentile) and in 48% of severely obese adolescents (BMI > 2.5 standard deviations
above the mean) [26]. The relative risk of metabolic syndrome in that study was increased 1.55 times
for each 0.5-unit increase in BMI z score. It is important to realize that although BMI and insulin
resistance are related, they are not synonymous. They make independent and different contributions
to increasing cardiovascular disease (CVD) risk [27].

DEFINITION INSULIN RESISTANCE SYNDROMES

The relative ability of a given amount of insulin secretion to dispose of serum glucose varies as
much as sixfold among apparently healthy adults. The highest third of individuals are referred to as
insulin resistant, and this resistance is associated with a number of disease states, including cardiovascular
disease, hypertension, stroke, type 2 diabetes, nonalcoholic fatty liver disease, and polycystic
ovarian syndrome. One fourth to one third of the variance in insulin resistance is related to being
overweight, and particularly to abdominal pattern obesity. Although most of the data about the insulin
resistance syndromes have been obtained from adults, it is increasingly clear that insulin resistance
is present in obese children and adolescents, and that the consequences are increasingly being seen
in the pediatric age group. Reinehr et al. were able to show improvement in insulin resistance in 6-
to 14-year-old patients over 1 year if treatment resulted in at least a 0.5 decrease in BMI z score [24].