title: The use of Achilles tendon sonography to distinguish familial hypercholesterolemia from other genetic dyslipidemias.
abstract: OBJECTIVE
  Achilles tendon (AT) xanthomas, specific for familial hypercholesterolemia (FH), may be clinically undetectable. We assessed the usefulness of AT sonography in the diagnosis of FH.
  
  
  RESULTS
  Sonographic AT characteristics were evaluated in 127 subjects with FH (81 genetically ascertained), 84 familial combined hyperlipidemia, 79 polygenic hypercholesterolemia, and 88 normolipidemic controls. Abnormal echostructure (sonographic xanthoma) was noted only in FH. AT thickness was higher (P<0.001) in FH men and women compared with all of the other groups and, in FH mutation carriers but not in others, correlated positively with low-density lipoprotein cholesterol (r=0.345; P<0.001) and negatively with high-density lipoprotein cholesterol (r=-0.265, P=0.015). Thickness thresholds for the diagnosis of FH with specificity >80%, as were derived from receiver operating curves, were 5.3 and 5.7 mm in men < and >45 years, and 4.8 and 4.9 mm in women < and >50 years, respectively. In FH mutation carriers, sonographic findings increased the clinical diagnosis of xanthomas from 35 (43%) to 55 (68%). Using thresholds in validation sets of 70 genetically identified FH and 54 dyslipidemic non-FH correctly classified 80% and 88%, respectively.
  
  
  CONCLUSIONS
  Sonographic AT characteristics are normal in non-FH dyslipidemias. Identification of suspected FH by ultrasound using sex- and age-specific AT thickness thresholds is recommended.
authors.affiliation: Unitat de Lípids, Servei d'Endocrinologia i Nutrició, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic, Barcelona, Spain.
authors.forename: Mireia
authors.initials: M
authors.lastname: Junyent
authors.forename: Rosa
authors.initials: R
authors.lastname: Gilabert
authors.forename: Daniel
authors.initials: D
authors.lastname: Zambón
authors.forename: Isabel
authors.initials: I
authors.lastname: Núñez
authors.forename: María
authors.initials: M
authors.lastname: Vela
authors.forename: Fernando
authors.initials: F
authors.lastname: Civeira
authors.forename: Miguel
authors.initials: M
authors.lastname: Pocoví
authors.forename: Emilio
authors.initials: E
authors.lastname: Ros
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006950:Hyperlipidemia, Familial Combined / Q000000981:diagnostic imaging* / Q000235:genetics; D006938:Hyperlipoproteinemia Type II / Q000000981:diagnostic imaging* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000379:methods / Q000592:standards; D014973:Xanthomatosis / Q000000981:diagnostic imaging / Q000235:genetics