Background

Children with brain tumors who develop hypothalamic obesity (HO) are at an increased risk for morbidity and mortality from cardiovascular disease (CVD). Although abnormal total lipid levels contribute to the development of CVD,higher proportion of small dense low density lipoprotein (LDL) phenotype (pattern B)has greater propensity for CVD and atherogenesis than the large (pattern A) and intermediate phenotypes.Conversely, higher proportion of large HDL are protective against CVD. We compared LDL and HDL subfractions in children with brain tumors and HO and those with simple obesity (SO).

Methods

A total of 23 children (age: 6-18 yrs) in two groups, HO (n=6) and SO (n=17; BMI>95th%) were studied. Total cholesterol, LDL, HDL along with LDL and HDL subfractions were measured using the Lipoprint Lipoprotein Subfraction testing system.

Results

LDL and HDL concentrations were similar in children with HO and SO (81 ± 18 mg/dL and 93 ± 28 mg/dL, p=0.3 and 36.8 ± 16 and 48± 17 mg/dL, p=0.19 respectively). Small dense LDL levels (class 3-7) were also not different between the two groups [median (25%ile-75%ile) 2.5mg/dL (0.75-5.5) in HO vs 2.7 mg/dL(1.1-4) in SO].However, HO and SO showed differences in phenotypical patterns that are algorithmically derived from particle size and weighted area% of individual subfractions. While SO had six each with pattern B and intermediate, in HO only one showed pattern B and the rest confined to pattern A.Percent of large HDL subfractions were not different between the two groups (24.2 ± 17.8 in HO vs 22.2 ± 10.2 in SO, p.0.05)

Conclusions

The LDL subfraction pattern, which is an indicator of risk for CVD, appears to be more favorable in children with HO than that in SO. The data are fascinating and further studies are warranted in larger cohorts to further explore the findings from this pilot study.