title: Buffalo hump seen in HIV-associated lipodystrophy is associated with hyperinsulinemia but not dyslipidemia.
abstract: Accumulation of dorsocervical fat, or a "buffalo hump" (BH), is commonly reported in adults with HIV-associated lipodystrophy (HIVLD). The pathogenesis underlying this aspect of a syndrome characterized by loss of subcutaneous fat from other body sites is poorly understood. We aimed to identify risk factors for a BH in HIV-infected adults in cross-sectional analyses of 2 HIV-infected ambulatory populations. The first group (Australian Lipodystrophy Prevalence Survey [APS]) consisted of 1348 Australian HIV-infected adults (95% male) irrespective of changes in body composition. The second group (Lipodystrophy Case Definition [LDCD] study) comprised 417 subjects (83% male) with at least 1 reported moderate or severe feature of HIVLD. A BH was reported in 24 (2%) APS subjects and 79 (19%) LDCD study subjects. A BH was not an isolated finding. Patients with a BH had a high prevalence of other features of HIVLD, similar to lipodystrophic patients without a BH, such as facial lipoatrophy reported in 100% and 61% BH-positive subjects from the APS and LDCD study, respectively. In both groups, those with a BH had higher fasting insulin (P<or=0.007), a higher body mass index (P<or=0.003), a higher waist/hip ratio (P<or=0.001), higher limb fat (P<or=0.003), and higher systolic blood pressure (P<0.05). On multivariate analysis, higher serum insulin, systolic blood pressure, age, and duration of exposure to ritonavir were independently associated with a BH in the APS group. In the LDCD group, higher insulin, diastolic blood pressure, and duration of exposure to zidovudine were independently associated with a BH. There was no association between a BH and hyperlipidemia. These data show that a BH is associated with other physical features of the lipodystrophy phenotype and suggest that hyperinsulinemia, a feature common to HIVLD, obesity, and hypercortisolism, is an important component of this phenotype, thus warranting closer monitoring of BH-positive patients for glucose intolerance and diabetes.
authors.affiliation: National Centre in HIV Epidemiology and Clinical Research, Faculty of Medicine, University of New South Wales, Sydney, Australia. pmallon@nchecr.unsw.edu.au
authors.forename: Patrick W G
authors.initials: PW
authors.lastname: Mallon
authors.forename: Handan
authors.initials: H
authors.lastname: Wand
authors.forename: Matthew
authors.initials: M
authors.lastname: Law
authors.forename: John
authors.initials: J
authors.lastname: Miller
authors.forename: David A
authors.initials: DA
authors.lastname: Cooper
authors.forename: Andrew
authors.initials: A
authors.lastname: Carr
mesh_terms: D000328:Adult; D001823:Body Composition; D016022:Case-Control Studies; D002574:Cervical Vertebrae; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D039682:HIV-Associated Lipodystrophy Syndrome / Q000097:blood* / Q000150:complications* / Q000473:pathology; D006801:Humans; D006946:Hyperinsulinism / Q000097:blood / Q000150:complications*; D006949:Hyperlipidemias / Q000097:blood / Q000150:complications; D007328:Insulin / Q000097:blood*; D008055:Lipids / Q000097:blood*; D008297:Male; D015999:Multivariate Analysis; D012307:Risk Factors
chemical_list: D007328:Insulin; D008055:Lipids