Most reference ranges are not considered sex-age specific differences. We collected about 700,000 health examination data with 24 items to estimate sex-age specific clinical reference ranges. We proposed nonlinear optimization method as a new method compatible with NCCLS guideline. All items showed sex-age specific differences of reference ranges. Especially, hepatic functions in young aged men and all aged women, diabetic functions in young aged people, blood pressures in older people, and total cholesterol in all aged people might have serious problems. Some abnormal individuals might not be detected using established reference ranges, on the other hand, some normal individuals might be treated excessively.