Insulin-Like Growth Factor-I, Insulin-Like Growth factor Binding Protein-3 and Blood Hemoglobin Concentration in an Elderly Population

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BACKGROUND: Insulin-like growth factor-I (IGF-I) serum level decreases with age, and this decrease may underlie hemoglobin (Hb) decrease. The objective of the study was to assess the relationship between IGF-I and insulin-like growth factor binding protein-3 (IGFBP-3) serum levels and Hb, after adjustment especially for major nutritional factors in an elderly population because IGF-I system depends on nutritional state, often impaired in the elderly. METHODS: Hemoglobin concentration was tested for 672 participants evaluated during an outpatient geriatric assessment. IGF-I and IGFBP-3 serum levels were assessed by Enzyme Linked Immunosorbent Assay. The molar ratio of IGF-I/IGFBP-3 that reflects the bioavailable IGF-I was calculated. Levels of IGF-I and IGFBP-3 were plotted against quartiles of Hb. Final linear models for IGF-I, IGFBP-3 and ratio molar included factors that could modify the Hb level. RESULTS: Mean age (SD) of the sample was 78.0 (8.5) years old and 32% were men. After adjustment for age and sex, IGF-I serum level, IGFBP-3 serum level and molar ratio significantly increased with increasing quartiles of Hb. After adjustment for age, gender, diabetes, albumin, pre-albumin, renal function, total cholesterol, angiotensin converting enzyme inhibitors and angiotensin II receptor blockers consumption, C-Reactive Protein, Hb was significantly associated and with IGF-I level (p = .002) and molar ratio (p = .02). CONCLUSIONS: IGF-I serum level and IGF-I/IGFBP-3 molar ratio were associated with Hb in an elderly population, independently of nutritional biological parameters. Thus, the association between the IGF-I system and Hb merits further investigation to determine whether interventions that modulate circulating IGF-I or IGF-I/BP3 ratio might preserve Hb in the elderly.

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