Dried blood spot sampling of testosterone microdosing in healthy females.

Capillary dried blood spot (DBS) analysis coupled with multi-analyte steroid liquid chromatography mass spectrometry (LCMS) is attractive for field studies, home-based self-sampling as well as clinical trials by eliminating costly and laborious sample processing involving venipuncture and frozen storage/shipping while providing multiple steroid measurements from a single small sample. We investigated steroid measurements in DBS samples stored for four years at room temperature prior to analysis compared with the original venipuncture serum samples. Healthy women (n=12) provided paired DBS and blood samples over two weeks run-in before seven days treatment with daily transdermal T gel (12.5 mg) and after the end of treatment on days 0, 1, 2, 4, 7 and 14. Compliance with treatment and sampling was high and no adverse effects were reported. Testosterone (T), androstenedione (A), 17 hydroxyprogesterone (17OHP) and progesterone (P) were measured in extracted DBS samples as whole blood concentrations with and without adjustment for hematocrit. Using the same LCMS methods, DBS T and A measurements had high correlation with minimal bias from prior serum measurements with DBS T displaying the same pattern as serum, with or without hematocrit adjustment. However, serial whole blood measurements of T without hematocrit adjustment provided the best fitting model compared with serum, urine, or hematocrit-adjusted whole blood T measurements. These finding facilitate and simplify DBS methodology for wider field and home-based self-sampling studies of reproductive steroids indicating the need for hematocrit adjustment may be superfluous.