FERTILITY AND STERILITY Copyright ~ 1978 The American Fertility Society
Vol. 29, No.5, May 1978 Printed in U.SA.
THE CATION COMPOSITION OF THE SEMINAL PLASMA AND PROSTATIC FLUID AND ITS CORRELATION TO SEMEN QUALITY
ZVI T. HOMONNAI, M.D.* HAIM MA TZKINt NACHUM FAINMAN, M.D. GEDALIA PAZ, PH.D. PERETZ F. KRAICER, PH.D.t
Soferman Institute for the Study of Fertility, Maternity Hospital, Tel Aviv-Jaffo, Israel
The concentrations of calcium, magnesium, and zinc were measured by atomic absorption spectrometry. The concentrations of all three cations were found to be strongly correlated with one another and with acidity (pH). Analysis of the relative concentrations in prostatic fluid, split ejaculates, and whole seminal plasma confirmed an almost exclusively prostatic origin of these cations. Semen quality, as judged by motility, vitality, concentration, and morphology of spermatozoa, was inversely related to cation concentrations. Therefore, we recommend adoption of the measurement of seminal divalent cations as part of the routine andrologic examination.
Although it is commonly accepted that the genital accessory glands play an important role in male fertility, experimental data demonstrating their involvement are sparse and limited. For example, it is known that prostatitis is associated with a decrease in the fertility of the male. I. 2 Study of the pathophysiology of the male accessory genital glands, primarily the prostate and seminal vesicles, requires extensive knowledge of the physiology and endocrinology of these glands. The secretory products of the accessory glands can be measured in the ejaculate and related, in some instances, to the activity of the glands. Few methods are available today for exploration of the functional condition of the accessory glands. First, chemical "markers" whose concentrations in the seminal plasma reflect the activity of the
gland of origin must be identified. The gland which lends itself most simply to this requirement is the prostate. 3 By rectal prostatic massage, secretory fluid can be expressed for chemical and cytologic analysis. At present, fructose is the marker for seminal vesicle secretion; inositol, acid phosphatase, citric acid, and zinc for the prostate. 4 The unique composition of seminal plasma implies a vital biologic function. It is assumed that the secretory products of the accessory glands are beneficial to the spermatozoa in the ejaculate. 5 The prostate secretes cations in large amounts. The three major cations are calcium, magnesium, and zinc. 4 , 6, 7 The purpose of this study was to evaluate the concentrations ofthese cations in the ejaculates of men and to correlate them with semen quality.
Received August 22,1977; revised November 14,1977, and December 16, 1977; accepted December 26, 1977. *Reprint requests: Z. T. Homonnai, M.D., Soferman Institute for the Study of Fertility, Maternity Hospital, P.O. Box 7079, Tel Aviv-Jaffo, Israel. tThis project was performed in partial fulfillment of the specialization requirements for the M.D. degree, Hebrew University, Jerusalem. tEstablished Investigator of the Chief Scientist's Bureau, Ministry of Health, Israel.
MATERIALS AND METHODS
During a 9-month period, 276 patients referred to our outpatient clinic were included in this study. Their wives had been examined and were found to be in the fertility range. At the first interview, a complete medical history was obtained, espe-
HOMONNAI ET AL.
cially with respect to any history of inflammation in the urogenital tract. Physical examinations were performed to exclude patients with discernible pathology of the secondary glands. A total of 1055 semen samples were obtained by masturbation. Two to five semen samples were collected from each man. The routine laboratory examinations included determination of semen volume, pH, sperm motility 1 hour after ejaculation, vitality by the eosin staining test, and sperm density by hemocytometry or DNA estimation. s Other parameters such as spermagglutination and semen liquefaction, viscosity, and color were found to be within the normal range. A spermiocytogram was performed on each specimen of semen. The smear of a drop of the ejaculate was stained with hematoxylin and eosin and the cells were classified according to the definitions introduced by MacLeod. 9 The patients were separated into four groups following a modification of the scoring system introduced by Eliasson,lo substituting vitality for grade of progressive motility. Seminal plasma (SP) was separated by centrifugation at 300 x gmax for 10 minutes and the supernatant was used for chemical analysis. Nine patients were asked to collect their ejaculates in two fractions (split ejaculate fractions I and II) and the chemical composition of each fraction was determined. Forty patients were found to be azoospermic and to have elevated levels of folliclestimulating hormone «470 ng/ml). Following digital prostatic massage, prostatic fluid was collected into a capillary tube and was analyzed for fructose, zinc, calcium, and magnesium concentrations. Fructose was measured by a modified resorcinol method. 7 Zinc was estimated in SP diluted 1:80 with distilled water; magnesium and calcium were estimated in diluted SP (1:120) in a solution of LaCl2 (0.5% w/v). Prostatic fluids were diluted 1:300 in the same solutions. All estimations were performed in a PerkinElmer 290 atomic absorption spectrophotometer. Statistical analyses were performed by using ttests; correlations were obtained by the computer at the Tel Aviv University.
30 165 ± 3.5 0-382 n = 1055
~ c: 0
30 131 ± 2·9 0-291
(",g / ml)
FIG. 1. Frequency polygons of the distributions of cation concentrations in seminal plasma. Means ± standard error of the mean, 95% confidence limits, and group sizes of the measurements are shown in the upper right quadrant of each histogram.
toward higher values, implying that the distribution could be normalized by transformation of the cation concentrations to logarithms. Logarithmically transformed values were tested for correlations (Fig. 2). All three cations showed highly significant (P < 10-4 ) correlations in all cases. A correlation line, the principal
r = 0.68
[zn] - 19.3
or 1.18 [MgJ - 3.6
1:;°(. [M9J = 0.37
The concentrations of the three cations measured-ealcium, magnesium, and zinc-are shown in Figure 1. It is apparent that the frequency distributions are not symmetrical but are skewed
FIG. 2. Correlations between cation concentrations in seminal plasma (calculated from logarithmically transformed data). All values of r are more significant than P = 10-4 • The correlation trend equations for calculating expected concentrations (in micrograms per milliliter) of other cations are shown.
Vol. 29, No.5
TABLE. 1. Differences between the Composition of First
and Second Fractions of Nine Split.Ejaculates Parameter
Sperm density (1()6/ml) Volume (ml)
Fructose (mg/ml) Zinc (~g!ml) Magnesium (~g/ml) Calcium (~g/ml)
CATIONS IN SEMINAL PLASMA AND PROSTATIC FLmD
54 ± 16.9
172 ± 44.6 1.4 2.2 215 188 436
1.5 3.9 74 79 194
± ± ± ±
Fraction 2 a
0.4 29.0 26.8 39.0
± ± ± ± ±
0.4 0.5 14.1 15.9 28.6
<0.025 <0.05 <0.001 <0.005 <0.001
"Values are' means ±. standard error of the mean. bCalculated by t-tests.
axis, was fitted to the data according to the method established by Sokal and Rohlf,11 permitting the expression of calcium and magnesium concentrations as the equivalent zinc concentration (Fig. 2), and vice versa for the other two cations. The mean pH of the semen samples was 7.62 ± 0.03 SEM. In all cases the cation concentrations were highly significantly correlated (J> < 0.001) with the. pH, all of the correlations being negative. In other words, an increase in the concentration of any or all of the cations was associated with greater acidity of the seminal plasma. . In nine split ejaculates, all three cations appeared mainly (67% to 72%) in the first fraction (Table 1). Furthermore, relatively large concentrations of these cations were found in prostatic fluid expressed by digital massage (Table 2).
. The values represented in Figure 1 were obtained from patients whose semen reflected the entire spectrum of quality. The relationship between cation concentration and semen quality was analyzed (semen quality was scored according to spermatozoal . motility, vitality, concentration, and cytology). In addition, semen from a group of azoospermic patients was included in the analysis. Cation concentrations tended to be lower in poorquality semen, excluding, however, semen from the azoospermic men (Fig. 3). DISCUSSION
Prostatic fluid was the major source of the three cations measured in this study.12 This was clearly demonstrated by comparing concentra-
tions of all three divalent cations in prostatic fluid, split ejaculates, and whole seminal plasma. Whereas calcium and. magnesium were diluted to the same .degree, zinc was diluted far less. This suggested a second, albeit more dilute, source for zinc (seminal vesicle fluid?). In this study we have. shown that there is a negative correlation between semen quality, as evaluated by the criteria of Eliasson, 10 and cation concentrations. This finding confirms the widely held concept that prostatic pathology is associated with reduced male fertility. 13-17 On the other ·hand, in azoospermia, no unusual changes in the concentrations. of the. three cations were noted. IS Since a priori there was no reason to expect a common etiology of azoospermia. and lowered · semen quality, this finding was not surprising. . The secretory activity of the prostate in general is known to be closely' controlled by androgens. Measurements of calcium, magnesium, and zinc should yield a convenient index of the prostatic response' to androgens .. In fact, our results demonstrate that measurements of allthree cations are .probably unnecessary. Measurement of the concentrations of any pair of these cations or even determination of the concentration of one yields almost as much information as measurements of all three. Determination of cation concentrations, not being a biochemical procedure, is fast, simple, and inexpensive if the necessary .instruments are available, as they usually are in any well-equipped laboratory. Since the cations are ·stable, as compared with the organic constituents or enzymes of semen, analysis can be delayed without concern. The estimation of cations, therefore, should be ideal for evaluating the prostatic response to ·treatment, for example, of prostatitis. In choosing a specific cation for study, the following points are relevant. (1) Calcium and magnesium are usually present in SP in much higher · concentrations than in blood plasma. Zinc, on the other hand, is. present in only trace amounts in blood and is therefore a more specific marker. (2) Zinc is secreted primarily by the prostate, but not exclusively. Calcium and magnesium appear to
TABLE 2.' Concentration of Cations in Prostatic Fluid and Concentration in the First Fraction of Split Ejaculates and in Seminal Plasma Relative to That in Prostatic Fluid Source
Prostatic fluid (~g/ml) Split fraction I (%") Seminal plasma (%a)
12 9 300
aper cent of concentration in prostatic fluid.
1280 ± 21 34 ± 30.2 25 ± 6.1
486 ± 13 39 ± 30.1 27 ±3.3
335 ±.13 64 ± 21.4 49 ± 13.6
HOMONNAI ET AL.
FIG. 3. Concentrations of cations and fructose in seminal plasmas of men with varying degrees of sperm quality, rated A (apparently normal) to D. The column labeled X represents azoospermic samples (which were included in group D). The shaded area represents the 95% confidence limits of the mean of group A. Other values are means ± standard error of the mean. Asterisks indicate significant differences. Because oflimitations in semen volume, not all the samples were analyzed for the various cations.
be more specifically prostatic in origin. Thus, changes in the prostatic secretion rate might be discerned more clearly by analysis of calcium and! or magnesium. At present there is no clear basis for preference for one or another of these cations. Each andrology laboratory should choose the one most convenient for its use. With more experience, it is possible that measurement of one or another will prove to have some advantage. Acknowledgments. Mrs. Halina Kornblum and Mr. Adin Sofer provided excellent technical collaboration. Dr. A. Weingarten, of the Department of Biochemistry, Tel Aviv University, instructed and supervised the measurements of the cations. REFERENCES 1. Eliasson R, Fredricsson B, Johannison E, Leander G: Biochemical and morphological changes in semen from men with disease in the accessory genital glands. In Proceedings of the Fifth World Congress of Fertility and Sterility, Stockholm. Amsterdam, Excepta Med Int Congr Ser 133:625, 1966 2. Eliasson R, Molin L, Rajka G: Involvement of the prostate gland and seminal vesicles in urethritis with special reference to semen analysis. Andrologia 2:179, 1970 3. MacKenzie AR, Hall TH, Whitmore WF: Zinc content of expressed human prostatic fluid. Nature 193:72, 1962 4. Eliasson R: Seminal plasma, accessory genital glands and infertility. In Male Infertility Work-up, Treatment and Research, Edited by ATK Cockett, RL Urry. New York, Grune and Stratton, 1976, p 189 5. Wales RC, White IG: The effect of alkali metal, magnesium, and calcium ions on the motility of fowl spermatozoa. Aust J BioI Sci 11:589, 1958
6. Eliasson R, Lindholmer C; Leander G: Zinc and magnesium in human seminal plasma. Int Urol Nephrol 2:309, 1970 7. Mann T: The Biochemistry of Semen and of the Male Reproductive Tract. London, Methuen, 1964, p 139 8. Paz G, Sofer A, Homonnai TZ, Kraicer PF: Human semen analysis. Seminal plasma and prostatic fluid composition and their interrelations with sperm quality. Int J Fertil 22:140, 1977 9. MacLeod J: The parameters of male fertility. Hosp Pract 43:12,1973 10. Eliasson R: Parameters of male fertility. In Human Reproduction, Conception and Contraception, Edited by ESE Hafez, TN Evans. New York,Harper and Row, 1973,p39 11. Sokal RR, Rohlf PJ: Biometry. San Francisco, Freeman, 1969, p 528 12. Lindholmer C, Eliasson R: Zinc and magnesium in human spermatozoa from different fractions of split ejaculates. Int J Fertil 19:45, 1974 13. Katz S, Praiss D, Debenedictis TJ: Semen zinc levels in infertile and postvasectomy patients. Fertil Steril 26:208, 1975 14. Colleen S, Mardh PA: Studies on non-acute prostatitis. Clinical and laboratory findings in patients with symptoms of non-acute prostatis. In Genital Infections and Their Complications, Edited by D Danielsson, L Juhlin, PA Mardh. Stockholm, Almqvist and Wiksell International, 1975, p 146 15. Janick J, Seitz L, Whitmore W: Seminal fluid and spermatozoon motility. Fertil Steril 22:573, 1971 16. Marmar JL, Katz S, Praiss DE, Debenedictis TJ: Semen zinc levels in infertile and postvasectomy patients with prostatitis. Fertil Steril 26:1057,1975 17. Colleen S, Mardh PA, Schytz A: Magnesium and zinc in seminal fluid of healthy males and patients with nonacute prostatitis with and without gonorrhea. Scand J Urol Nephrol 9:192, 1975 18. Nawson CA, Fischer MI: Zinc in aspermic human semen. Nature 177:190, 1956