Biomarkers in Urine
In 1938, it was discovered that the urine of a woman could be injected into frogs as a way to test for pregnancy (1). If the frogs laid eggs after the injection, then the woman was pregnant. The assay had a relatively quick turn-around time, was simple, and generally accurate…the principle being that the hCG hormone excreted in urine of pregnant women caused the frogs to lay eggs. However, as always, there was a better way.