Immunoreactive somatomedin B (RIA-B) in the circulation of healthy adults and patients with endocrine disorders.

The serum and cerebrospinal fluid (CSF) levels of immunoreactive somatomedin B (RIA-B) were examined throughout life in healthy adult humans. A significant decline in serum RIA-B was observed in subjects over 60 years of age. No significant diurnal, daily, or monthly serum variation was observed in healthy subjects aged 20-60 years. However, women taking oral contraceptives had elevated RIA-B values. No significant decline in CSF RIA-B was observed in subjects over 60 years of age. A significantly lower level of RIA-B in CSF was observed in subjects sampled at 20.00 h compared to subjects sampled in the morning. A significant decline in serum RIA-B was observed in patients with hypopituitarism and diabetes mellitus and a significant elevation of serum RIA-B levels was observed in patients with hyperthyroidism. CSF RIA-B was significantly elevated in patients with Cushing's syndrome.