Pregnancy-associated alpha 2-glycoprotein (alpha 2-PAG): development of a sensitive enzyme-linked immunoassay and comparison of serum concentrations in adults and children.

Using a newly-developed and very sensitive enzyme-linked immunoassay technique, we have measured circulating alpha 2-PAG concentrations in 270 adults and 181 children. In adults, levels increased with age in both sexes and were significantly higher in women in each age category studied. In contrast, there were no significant differences between the sexes in children and no changes with age between 1 and 14 years. At puberty, alpha 2-PAG concentrations increased in girls and decreased in boys. The increase in girls is consistent with the known stimulatory effects of oestrogen on alpha 2-PAG production. We discuss the possibility that androgens may have an analogous inhibitory effect in males.