Insulin-like Growth Factor I and Insulin-like Growth Factor Binding Protein 3 as Determinants of Blood Hemoglobin Concentration in Healthy Subjects

Abstract

We studied the serum concentrations of IGF-I, IGFbinding protein 3 (IGFBP-3), and testosterone in relation to blood Hb in 60 healthy prepubertal or early pubertal boys twice, with a 9-mo interval. Serum IGF-I and testosterone levels were measured by RIA, and serum IGFBP-3 was measured by monoclonal immunofluorometric assay. Positive correlations were observed between the concentrations of blood Hb and serum IGF-I at the first examination (r = 0.36, p = 0.008) and Hb and IGFBP-3 at both examinations (r = 0 . 5 3 ,~ < 0.001, and r = 0 . 3 9 ,~ = 0.003). No association between Hb and testosterone concentrations was found. Our results show that blood Hb is positively correlated to serum IGF-I and IGFBP-3 levels, indicating indirectly the involvement of growth hormone in the regulation of physiologic Hb concentration. Because no association was found between Hb and testosterone concentrations, this may indicate that the role of androgens in erythropoiesis may be different at different stages of puberty. It is concluded that the IGF system may be involved in the rise of Hb level during early puberty. IGF-I and IGF-I1 act as mediators of growth hormone actions and participate in the regulation of cell division, growth, and differentiation (1). The serum concentration of the major IGF-binding protein (IGFBP-3) reflects the total amount of IGF-I and IGF-I1 in the circulation and the secretion of growth hormone similarly or even better than the serum concentration of IGF-I alone (2). IGF-I has a role in the regulation of the erythropoietic system in vitro and also in vivo (3-9). IGF-I stimulates proliferation of murine and human erythroid progenitor cells in bone marrow culture systems (4, 6). The optimum in vitro erythropoiesis appears to depend on several systems, including erythropoietin, stem cell factor, IGF-I, and unidentified factors (8, 9).The stimulatory effect of androgens on erythropoiesis is well documented (10). Thomsen et al. (11) found that the marked rise in blood Hb concentration takes place during a short period in male puberty coinciding with an Supported by grants from the Sigrid Juselius Foundation, the Academy of Finland, the Cancer Society of Finland, the University of Helsinki, Finland, and the Nordisk Insulin Foundation Committee. increasing serum testosterone level. We studied the role of serum concentrations of IGF-I, IGFBP-3, and testosterone in the maintenance of blood Hb concentration in 60 healthy prepubertal or early pubertal boys twice, with a 9-mo interval. Possibly several regulatory mechanisms of increasing erythropoiesis have different roles at different stages of male puberty. METHODSSubjects. An opportunity to participate in the study was offered to 84 boys of the same secondary school level in three schools near the Children's Hospital, Helsinki. The study was approved by the parents, the school authorities, those responsible for school health care, and the Ethical Committee of the Children's Hospital. Written information about the study was sent to the families. Of the 84 boys, 62...

Interpretation of automated blood cell counts

“…Bu dönemde demir profilaksisi önerilmek-tedir. Son olarak püberte döneminde hormonal deği-şimlere bağlı olarak kızlarda menstrüel kan kaybına bağlı demir eksikliğine eğilim erkeklerde ise yük-sek Hb değerleri görülmektedir [26,27]. Riskli gebeliklere ve doğum stresine bağlı olarak annede artan stres hormonların etkisiyle yenidoğan lökositoz ve nötrofiliye eğilimle doğar [29].…”

Body iron stores in relation to growth and pubertal maturation in healthy boys

“…At this point the mean serum ferritin was 32 4 mg/kg at 24 months. The serum concentrations of IGFBP-3 (Anttila et al, 1994) and testosterone showed no correlation with serum ferritin or estimated iron stores. Nor were they associated with the preceding annual change in ferritin or iron stores.…”

“…Serum testosterone concentrations were determined by radioimmunoassay (Apter et al, 1976). In this study we also had access to the serum IGFBP-3 concentrations reported by Anttila et al (1994).…”

Developmental Genetics of Red Cell Indices During Puberty: A Longitudinal Twin Study

“…Thomsen et al (1986) found that a steep rise in haemoglobin concentration in pubescent boys took place during a short period in adolescence, soon after an increase in testosterone production. In contrast, Anttila et al (1994) in a study of younger boys, failed to find an association between serum testosterone and haemoglobin levels, but did find an association between serum IGF-1 and haemoglobin. These results imply that different systems and consequently different sets of genes may regulate red cell indices at different stages of puberty.…”

“…From childhood to adulthood, however, there is an increase in these and other indices of erythrocyte number and size. This increase is greater in males than females and is probably due to the combined action of several hormones including testosterone and insulin-like growth factor (IGF-1) that are secreted in increased amounts during adolescence (Anttila et al 1994;Thomsen et al 1986).…”