Scientists created a very sensitive test to measure thymosin‑alpha‑1 in blood, showing it’s stable and doesn’t break down during collection. They found the peptide is highest before birth, drops after birth, and stays fairly steady through childhood, while pregnant mothers have higher levels. This tells us the natural levels of the peptide in the body but doesn’t give dosing or performance tips.

A sensitive and specific radioimmunoassay (RIA) has been developed to measure thymosin alpha 1 in human blood and tissue extracts. Thymosin alpha 1, originally isolated from bovine thymosin fraction 5, has an identical primary structure in bovine and human species. Antiserum to synthetic thymosin alpha 1 was prepared in rabbits. A synthetic analogue, N-Ac-(Tyr1)thymosin alpha 1 was radioiodinated by utilizing Na125I and soluble lactoperoxidase. The RIA is capable of detecting as small an amount as 40 pg thymosin alpha 1 in serum/plasma and does not significantly cross-react with other putative thymic hormones or other purified blood proteins that have been assayed. Proteolytic degradation of thymosin alpha 1 does not occur during the collection, storage, or assay of serum or plasma. The concentration of thymosin alpha 1 in the blood is highest in utero, decreases sharply after birth, and appears to remain fairly constant during the first 15 yr of life. Maternal blood levels of thymosin alpha 1 appear to be above normal during pregnancy.