Table 2. Diagnostic criteria for heterozygous FH in adults (15 years of age or older).

1. Hyper-LDL-cholesterolemia (an untreated LDL-C level of ＞= 180 mg/dL) 2. Tendon xanthoma (tendon xanthoma on the backs of the hands, elbows, knees, etc. or Achilles tendon hypertrophy) or xanthoma tuberosum 3. Family history of FH or premature CAD (within the patient's second-degree relatives)

・The diagnosis should be made after excluding secondary hyperlipidemia. ・If a patient meets two or more of the above-mentioned criteria, the condition should be diagnosed as FH. In cases of suspected FH, obtaining a diagnosis using genetic testing is desirable. ・Xanthoma palpebrarum is not included in xanthoma tuberosum. ・Achilles tendon hypertrophy is diagnosed if the Achilles tendon thickness is ＞= 9 mm on X- ray imaging. ・An LDL-C level of ＞= 250 mg/dL strongly suggests FH. ・If a patient is already receiving drug therapy, the lipid level that led to treatment should be used as the reference for diagnosis. ・Premature CAD is defined as the occurrence of CAD in men ＜55 years of age or women＜65 years of age, respectively. ・If FH is diagnosed, it is preferable to also examine the patient’s family members.