PHILADELPHIA, PA— Insulin-like growth factor (IGF-1) and sex steroid hormones were not associated with changes in bone mineral density (BMD) in HIV- and HCV-infected patients, but IGF-1 levels were significantly decreased in HCV and negatively correlated with liver disease severity, a study reported at IDWeek 2014.
HIV and HCV infection are associated with higher rates of osteoporosis and fragility fractures, and have both been shown to reduce BMD, but likely through different mechanisms. “IGF-1 and sex steroids testosterone (T) and estradiol (E2) play a key role in osteogenesis, but their contribution to bone health in HIV and HCV infection is unknown,” reported James Cutrell, MD, from the VA North Texas Health Care System, Dallas, TX.
To evaluate the association of IGF-1 and sex steroid levels with BMD and bone turnover markers (BTMs) in patients with HIV and HCV, Dr. Cutrell and colleagues conducted a prospective cross-sectional study of male veterans (≥40 years old) with no known osteoporosis.
A total of 298 subjects were included in the study, comprising 81 patients with HIV infection (all on HAART), 79 with HCV (all HCV treatment-naïve), 31 with HIV/HCV co-infection, and 107 controls. Measurements included: BMD by DXA scan; BTMs by serum C-telopeptide (CTX), osteocalcin, and bone-specific alkaline phosphatase (BSAP); hormones IGF-1 by insulin-like growth factor binding protein 3 (IGFB3), total T, total E2, and sex hormone binding globulin (SHBG); and APRI (AST-to-platelet ratio index) as a marker of lower fibrosis.
IGF-1 levels were significantly decreased in HCV infected patients (P<0.01), but increased in HIV infected patients (P<0.03). IGF-1 was also negatively correlated with APRI score in all groups (-0.214; P<0.01), and associated with higher BSAP (P=0.04).
HCV-infected patients also had higher levels of serum T (P<0.01) and E2 (P<0.05), which may be due to higher levels of SHBG (P<0.01). Levels of bioavailable T and E2 were associated with lower BSAP (P<0.01 and P=0.02, respectively), but not osteocalcin or CTX.
Multivariate analysis found that HIV and HCV were independently associated with lower femoral neck BMD after controlling for risk factors, but there was no association with BMD and IGF-1 levels or bioavailable T or E2, and IGF-1 levels did not attenuate the effect of HIV and HCV on BMD.
“Differences in mechanisms of bone loss in HIV and HCV do not appear to be explained by differences in levels of these hormones,” concluded Dr. Cutrell.