Disorders of lipid metabolism in adolescents with simple obesity

Background: Obesity affects approximately 45 millions of children worldwide. Some of them present with secondary dyslipidemia that leads to premature atherosclerosis.

Objective: 1) Assessment of the frequency and type of dyslipidemia in obese adolescents. 2) An attempt at defining risk factors of atherogenic lipid profile in obese adolescents.

Methods: In 146 (84 girls/62 boys) obese (mean BMI SDS 4.95, 95% CI 4.62-5.29) adolescents (age 10-18, mean 14.7 years), the levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDLc), high-density lipoprotein cholesterol (HDLc) and triglicerydes (TG) were measured. Atherogenic dyslipidemia was defined as a high TG level with a concomitant low HDLc level. Standard oral glucose tolerance test was performed with the assessment of fasting and after 120' post-load of 75 g of glucose and insulin levels; the insulin resistance index HOMA-IR was calculated.

Results: The mean values of the lipid fractions were in normal ranges: TC 4.64 mmol/L (95% CI 4.48-4.8), LDLc 2.86 mmol/L (95% CI 2.73-2.99), TG 1.4 mmol/L (95% CI 1.3-1.5), and HDLc 1.16 (95% CI 1.1-1.2). However, in 50.69% of the patients (45.24% girls and 58.06% boys), elevated levels of TC, LDLc, and TG were observed respectively in 23.29%, 17.81% and 37.67%, and low HDLc in 15.07% of patients. A total of 10.96% of the patients presented with coexistence of a low HDLc and a high TG. In 26.7%, dyslipidemia was followed by arterial hypertension. There was a reverse correlation between a low HDLc value and BMI SDS [R (-) 0.22, p < 0.05] and not with TC, LDLc, and TG. The relative risk of abnormal lipid profile occurrence was higher in obese patients with insulin resistance (OR 1.72; 95% CI 0.8-3.4; p = 0.12), being significant only for boys (OR 3.67; 95% CI 1.1-12.1; p = 0.03). There was a reverse correlation between fasting insulin level, HOMA-IR and HDLc [R (-) 0.2; p < 0.05; R (-) 0.2; p < 0.05) respectively], as well as TG (R 0.26 ; p < 0.05; R 0.26; p < 0.05, respectively), and between post-load insulin level and TG (R 0.24; p < 0.05).

Conclusions: 1) Lipid disorders occur in about one-half of obese adolescents, of which 10% presents with atherogenic lipid profile. 2) One of the most important risk factors of atherogenic lipid profile occurrence is insulin resistance, especially in boys. The severity of the obesity (BMI-SDS) is of lesser importance.