The laboratory reliability and validity of sex hormone measurements we
re examined at multiple levels, including lower levels characteristic
of children and postmenopausal women. Serum was drawn from four adult
male and four adult female healthy volunteers, From each individual's
serum pool, a medium- and a low-dilution pool were created. Biochemica
l analyses for total and non-sex hormone-binding globulin (SHBG)bound
estradiol, estrone, estrone sulfate, progesterone, and SHBG were perfo
rmed on female samples. Male samples were analyzed for total and non-S
HBG-bound testosterone, dihydrotestosterone, androstenedione, and dehy
droepiandrosterone sulfate. Two aliquots from each pool were assayed t
wice in each of two labs, All assays except SHBG in one lab used RTA p
rocedures. Reliability was assessed by variance components analyses an
d estimated coefficients of variation (CVs). Validity was assessed by
comparing observed measurements versus expected values based on known
dilution ratios. For the testosterone and dihydrotestosterone assays,
CVs were usually less than 10%, For estradiol and progesterone, CVs we
re usually less than 15%. Assays with larger estimated CVs included an
drostenedione, dehydroepiandrosterone sulfate, estrone, and estrone su
lfate. Absolute levels differed markedly between labs for most assays.
Observed measurements generally agreed with values expected from the
dilution ratios. A notable exception was the estrone assay at the loa
est dilution level, where observed measurements were 2-4 times those e
xpected. A similar but less pronounced overestimation bias for the low
levels of estradiol was also suggested. This intra- and interlaborato
ry variability and apparent low dilution overestimation should be acco
unted for in studies relating hormones to cancer risk, especially thos
e involving children and postmenopausal women.