Penile xenon washout studies

LETTERS

TO THE EDITOR

SIGNIFICANCE OF PAP LEVELS

OF TRANSIENT AFTER TUR

ELEVATION

To the Editor: In the article, “Serum Acid Phosphatase Elevation Associated with Transurethral Resection Syndromes,” published in the October issue (vol. 22, page 388) of UROLOC~ Dr. I? D. O’Donnell presents the intriguing hypothesis that transiently elevated prostatic acid phosphatase (PAP) levels after transurethral resection (TUR) of the prostate may indicate significant intraoperative absorption of prostatic tissue substances and provide an explanation for the “TUR syndrome.” One should keep in mind, however, that any situation that disrupts the integrity of the prostatic capsule is likelv to permit release of PAP from the prostate, resultmg in increased levels of this enzyme in the blood and bone marrow. We compared PAP levels preoperatively and immediately postoperatively in 48 men with benign prostatic hyperplasia and found an average five-fold increase, with 3 patients having more than a thirty-fold increase.* None had a clinical TUR syndrome. A similar comparison in 16 patients with carcinoma of the prostate also showed an increase in PAP immediately postoperatively, although not as great as in the patients with benign lesions. In all cases, PAP returned to preoperative levels within one to four days. The degree to which PAP is raised after prostatic manipulation seems to reflect its concentration in the underlying tissue: benign tissue is rich in PAP; carcinomatous tissue, with its impaired ability to synthesize the enzyme, contains much lesser amounts. It would be most interesting to compare the preand postoperative PAP levels in patients with and without a TUR syndrome (although the difficulty of collecting a series in sufficient numbers is great) to verify the hypothesis outlined by Dr. O’Donnell.

genie Impotence,” by Dr. U. 0. Nseyo et al. published in the January issue (vol. 23, page 31) of UHOI,OGYwas most interesting and stimulates several comments. Xenon washout studies are well known for sensitivity to temperatdre variation.* Does the ambient room temperature used represent adequate control of this factor? While there were apparent problems with prolonged Xenon-133 clearance with intracorporeal injections, one wonders whether subcutaneous injections accurately reflect flow in the cavernosal arteries of the penis. In regard to the formula on page 32, our understanding of the Kety-Schmidt equation is:

Q

=

P where X is blood-skin partition coefficient for Xenon 0.7 ml/Cm P = specific gravity of skin of 1.05 K = slow constant of disappearance of Xenon133 Q = perfusion in mllmin/lOO Gm K can also be expressed ln2/T% therefore

Q

=

435 (1974).

PENILE

XENON

To the Editor: Washout:

624

A Rapid

WASHOUT

STUDIES

The article, “Penile Xenon (133Xe) Method of Screening for Vasculo-

100 * X * ln2 T% *P

The article failed to address whether the washout curves for Xenon were monoexponential or multiexponential. Only monoexponential curves can be utilized for the determination of blood flow unless curve-stripping techniques are employed to look at the various components of flow expressed by multiexponential curves. John P Collins, Division

M.D. of Urology

Karen Y. Gulenchyn, M.D. Division of Nuclear Medicine

Sumner Marshall, M.D. Department of Urology University of California San Francisco, California 94143 *Marshall S, Lyon RP, and Scott MP Jr: Prostatic acid phosphatase levels, significance in serum and bone marroxv, Urology 4:

100 - X * K

’

Ottawa Civic Hospital University of Ottawa Ottawa, Ontario

*Daly MJ, and Henry RE: Quantitative measurement perfusion with Xenon-133, J Nucl Med 21: 156 (1980).

REPLY

of skin

OF DR. NSEYO

We wish to thank Dr. Collins for their comments and drawing

UROI.OGY

/ JUNE 1984

and Dr. Gulenchyn our attention to the

/ VOLUME

XXIII.

NUMBER

6