Why is screening lipid profile in high school beneficial?

Good for prevention. If lipid profile is done at early age especially premature cardiovascular disease, abnormal lipids can be corrected with diet exercise medications to prevent cardiovascular disease.
HighSchool too late. Both the national lipid association and the national heart lung & blood institute recommend screening at age 9-11 to detect inherited (genetic) cholesterol disorders (specifically familial hypercholesterolemia). This is because of the changes that take place in the lipid panel during puberty that can alter the lipid panel. All should be screened by age 20 if missed earlier.