Relationship between IGF-1 and Anemia in Older Subjects: Cross Sectional and Longitudinal Data from the InCHIANTI Study

Background. The prevalence of anemia is higher in older people, where predicts disability and mortality(1).Among different potential mechanisms involved in the anemia of aging attention has been devoted to the decline of anabolic hormones especially testosterone(T)(1,2).IGF-1 can also contribute to the age-related decline in hemoglobin (Hb) levels(3),but only one study in adult population has tested the link between low IGF-1 and anemia(4).Thus,we addressed this hypothesis in older subjects.Materials and Methods.The population included 402 men, 536 women 65 yr older of the InCHIANTI Study with data on Hb, IGF-1 levels and T at baseline and Hb after 3 years.Serum IGF-1 were measured by IRMA.The MDC was 0.80 ng/mL with CVs<10%. T was measured by RIA.The MDC for T was 0.03 nmol/L,the intra and interassay CV were<10%.The MDC was 0.1 pg/mL and interassay CV of 4.5%. Anemia was defined according to WHO criteria.Linear regression models were used to test the relationship between IGF-1 and Hb and between IGF-1 and anemia in model 1 (adjusted for age) and in model 2 adjusted for age,T, erythropoietin,IL-6,BMI, energy intake,vitamin B-12, ferritin, folic acid, iron and liver function.Logistic regression models adjusted for baseline Hb levels were used to test the relationship between IGF-1 and anemia after 3 years, in not anemic patients.Results. The mean age was 74.7±7.0 (years ± SD) in men and 76.5±7.7 in women. 45 men (11.2%) and 71 women (13.2%) were anemic.IGF-1 levels (ng/ml) were lower in anemic men (100.3±54.2) and women (89.1 ± 48)compared to non anemic men (129.7±55.8) and women (109.6 ± 51.7).The difference in IGF-1 levels between the two groups was significant in men (p = 0.0009) and women (p = 0.002)and almost significant after adjustment for age in men (p = 0.08) and women (p=0.16).After adjustment for age, IGF-1 was positively associated with Hb in men (β±SE 0.59 ± 0.14, p<0.0001)and women(β±SE 0.16 ± 0.08, p=0.048).After further adjustment for T and other confounders the relationship between IGF-1 and Hb was still significant in men (β±SE 0.47 ± 0.12, p<0.0001), but not in women (β±SE 0.06 ± 0.07, p=0.39).IGF-1 levels were not independent predictors of anemia in men and women.Conclusions.IGF-1 is positively and independently associated with Hb in older men and women. Anemic older patients, especially men, have lower levels of IGF-1 independent of age and other confounders. However IGF-1 is not an independent predictor of anemia in both men and women.