Estrogen is the primary female sex hormone as well as a medication. It is responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens in women and men: estrone, estradiol, and estriol. This test does not specify each of these estrogens.

This ultrasensitive estradiol test is recommended for men. The commonly used estradiol test may overestimate estradiol in men. That test uses immunoassay technology that cannot differentiate C-Reactive Protein (involved in inflammation) from estradiol, so it reads the combination of the two as estradiol. This ultrasensitive estradiol test is based on liquid chromatography/mass spectrometry (LC/MS), an assay technology that does not have that limitation. 

Important note:  The blood sample is sent out to Quest Diagnostics Nichols Institute San Juan Capistrano, Caifornia.  Overnight delivery and testing is performed on Sunday and Friday.  Reports are available within 5-7 business days from the time the specimen is collected.

Estrone (E1) is one of the three estrogens, which also include estriol and estradiol. Estrone is the least abundant of the three and is considered a pro-hormone of estradiol.