Elevated LDL cholesterol not associated with BMI z-score in schoolchildren
MedWire News: Japanese researchers say that schoolchildren should maintain a body mass index z-score (BMISD) within the normal range to prevent future development of cardiovascular disease (CVD).
However, causes of CVD other than BMISD should be also considered, especially in cases of hyper low-density lipoprotein (LDL)-cholesterolemia, they remark.
Takao Ohta (University of the Ryukyus, Okinawa, Japan) and colleagues evaluated the association between adverse levels of CVD risk factors (conventional, C-reactive protein [CRP], uric acid [UA], and adiponectin) and BMISD (adjusted for age and gender based on the Ministry of Education, Culture, Sports, Science, and Technology data for Japanese schoolchildren), and the effect of insulin resistance (IR) on these associations in over 1000 Japanese schoolchildren, aged between 7 and 12 years.
Levels of CVD risk factors were considered to be adverse if they were above the 90th percentile for the study population, except for high-density lipoprotein (HDL) cholesterol and adiponectin, which were considered to be adverse when below the 10th percentile.
The researchers report that BMISD was linearly associated with the risk for having adverse levels of all CVD risk factors, except for glucose and low-density lipoprotein (LDL) cholesterol in boys, and glucose, LDL cholesterol, and adiponectin in girls.
These associations were weakened after adjustment for IR, notes the team, but still significant for UA and CRP in boys and UA, HDL cholesterol, and CRP in girls.
Commenting on their findings in the journal Pediatrics International, Ohta et al say that IR appears to contribute to most of the observed associations between BMISD and CVD risk factors. However, unexpectedly, LDL cholesterol was not associated with BMISD in both boys and girls, and, after adjusting for IR, associations between BMISD and HDL cholesterol were only retained in girls.
These findings suggest that familial hypercholesterolemia and familial combined hyperlipidemia "should not be overlooked in school children with overweight and obesity," comment the authors. Indeed, the effect of genetic factors on hyper-LDL cholesterol "may be greater than that of environmental factors," they say.
In addition, low HDL cholesterol in school girls should not be diagnosed as a complication of overweight and obesity before clarifying the genetic background, they conclude.
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By Nikki Withers