Dr. Crisler on his forum recently commented that there were some issues with the LabCorp sensitive E2 assay reading low but a rep told him they have been now been resolved.
I contacted one of their scientific directors to get the real story. What happened was a lab tech mixed up a batch of about 130 specimens and reported out the wrong results. Fortunately, LabCorp caught the mistake after reviewing the quality control results and has since contacted all of the patients/doctors and given them the corrected results.
Believe me, mistakes happen in the lab biz, but it's good to see that this one was resolved quickly.
This assay, like all the rest, does have some interference from other estrogens (estrone for example) and if you want the most accurate test you need to order the LC/MS E2 assay.
One interesting fact I was told is that menopausal women are the main users of the sensitive assay.