Enzymatic determination of estradiol and estrone in plasma and urine

Plasma and urine estradiol and estrone can be determined using the trans-hydrogenase function of the estradiol dehydrogenase of human placenta: in the conditions described the transhydrogenase activity which is directly related to the estrogen concentration is measured by spectrophotometry. Estrone and estradiol can be determined together or separately if estrone is previously reacted with hydrazine with a limit of sensitivity of 10 picograms in the sample. On urine samples the assay is performed directly without extraction, a simplification which makes the method highly suitable for numerous routine determinations.