Serum free IGF‐I, total IGF‐I, IGFBP‐1 and IGFBP‐3 levels in an elderly population: relation to age and sex steroid levels
- 1 April 1998
- journal article
- research article
- Published by Wiley in Clinical Endocrinology
- Vol. 48 (4), 471-478
- https://doi.org/10.1046/j.1365-2265.1998.00300.x
Abstract
Most previous studies concerning the relationship between IGF-I and age used assays measuring total IGF-I. Although free IGF-I is considered of greater biological relevance, little is known about its relationship with sex steroids levels in elderly healthy subjects. In a cross-sectional study of 218 healthy people (103 men, 115 women) aged 55–80 years we measured serum total and free IGF-I, IGFBP-1 and IGFBP3 levels and sex steroids. Free androgen index and free oestradiol index were used as an indicator for free oestradiol and free testosterone levels, respectively. Free IGF-I levels did not decline with age in the whole study population. Free IGF-I levels even increased in individuals above 70 years of age in comparison to those aged between 55 and 70 years (mean ± SE 0.106 ± 0.007 nmol/l vs. 0.086 ± 0.004 nmol/l, P = 0.009). Total IGF-I and IGFBP-3 decreased with age (r = −0.20, P = 0.005 and r = −0.24, P = 0.001, respectively). Total IGF-I levels were positively related with free oestrogen index in both sexes. Free IGF-I did not relate to free oestrogen or androgen index. In women only, free IGF-I was related positively with DHEAS while IGFBP-1 was inversely correlated with DHEAS. Free IGF-I levels do not decrease with age and are even higher in individuals above 70 years. There was no relationship between free IGF-I and free androgen or oestrogen index in either gender. We hypothesize that higher free IGF-I levels in older persons may be the consequence of selective survival in the cohort: subjects with high free IGF-I levels may live longer. The absence of a relationship between free IGF-I levels and free androgen and oestrogen indices suggests that there is no direct interaction between the biological activity of circulating IGF-I levels and sex hormone production in a healthy ageing population.Keywords
This publication has 28 references indexed in Scilit:
- Effect of short-term fasting on free/dissociable insulin-like growth factor I concentrations in normal human serumJournal of Clinical Endocrinology & Metabolism, 1996
- Serum concentrations of free and total insulin‐like growth factor‐I, IGF binding proteins ‐1 and‐3 and IGFBP‐3 protease activity in boys with normal or precocious pubertyClinical Endocrinology, 1996
- Free insulin‐like growth factors (IGF‐I and IGF‐II) in human serumFEBS Letters, 1994
- Increased proteolysis of insulin-like growth factor-binding protein-3 (IGFBP-3) in noninsulin-dependent diabetes mellitus serum, with elevation of a 29-kilodalton (kDa) glycosylated IGFBP-3 fragment contained in the approximately 130- to 150-kDa ternary complexJournal of Clinical Endocrinology & Metabolism, 1994
- Aging and Growth HormoneHormone Research, 1993
- Serum IGF-Binding Protein-3 is Related to IGF-I, But Not to Spontaneous GH Release, in Healthy Old MenHormone and Metabolic Research, 1992
- Insulin-like growth factors (IGFs): Implications for agingPsychoneuroendocrinology, 1992
- Inter‐relations between growth hormone, insulin, insulin‐like growth factor‐l (IGF‐I), IGF‐binding protein‐1 (IGFBP‐1) and sex hormone‐binding globulin in acromegalyClinical Endocrinology, 1991
- Cigarette Smoking and Levels of Adrenal Androgens in Postmenopausal WomenNew England Journal of Medicine, 1988
- Evaluation of a radioimmunoassay for testosterone estimationJournal of Steroid Biochemistry, 1973