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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 -80C 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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