Quantification of Prostatic Androgens
Part 1. Method Using Needle Biopsy Specimens
David L Hess, Beaverton, OR, Leonard S Marks, Frederick J Dorey, Maria
L Macairan, Arlyn S Llanes, Los Angeles, CA. (Presentation by Dr. Hess)
Abstract to be presented at the 2001 AUA Meeting in Anaheim, CA on
Wednesday, June 5, 2001.
INTRODUCTION AND OBJECTIVES: Prostate (P) levels of DHT were
previously studied using whole P or large quantities of surgically-excised
P tissue. We modified an existing assay method and measured P tissue levels
of DHT (and testosterone, T) in P biopsies (Bx) weighing as little as
a few mg.
MATERIALS AND METHODS: Prostate samples (mean weight = 7.6 mg,
range = 1.5-16.2 mg) were obtained from 20 men with symptomatic BPH (mean
age = 68 yo), who were undergoing 18 ga. needle Bx to rule out cancer
(n=16) or TURP for relief of obstruction (n = 4). 7 men were on long-term
finasteride (F) therapy and 13 were untreated controls. Specimens were
flash frozen on dry ice and stored at -80°C until assay. Tissues were
homogenized, and microcolumn (2.5g LH20/column) chromatography was used
to isolate individual T/DHT fractions after diethylether extraction. T
and DHT were determined by RIA and results expressed in ng/g P tissue.
Steroid recovery, determined by addition of tritiated-T and C-14-DHT to
samples processed in parallel with RIA samples, was 73% for T and 84%
for DHT. 10 samples from each TURP specimen were analyzed to determine
sampling variability.
RESULTS: Differences between controls and F-treated men (mean
± S.D.) are tabulated below (* denotes p<0.01):
| |
Serum DHT (ng/ml) |
Serum T (ng/ml) |
Tissue DHT (ng/g) |
Tissue T (ng/g) |
| Controls |
0.48 ± 0.24 |
4.59 ± 2.7 |
4.89 ± 2.1 |
1.89 ± 1.1 |
| Finasteride |
0.14 ± 0.09* |
3.26 ± 1.6 |
1.42 ± 0.9* |
4.91 ± 3.3* |
Serum and tissue DHT levels were correlated (r = 0.62, p < 0.05). Sampling
variability was appreciable (coefficient of variation = 0.23 - 0.61) but
still allowed complete separation of F-treated and control patients. Estradiol
was not detected in these tissues.
CONCLUSION: These results are virtually identical to those seen
when much larger quantities of tissue are conventionally assayed in similar
clinical situations. Steroid recovery via use of microcolumn chromatography
enhances sensitivity of the test. Thus, androgen concentrations in P tissue
may be determined on biopsy specimens. This method may be useful in testing
new therapies by permitting direct analysis of changing androgen status
within the prostate.
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