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Perspectives and Editorials |
In the study of andrology, laboratory assessment constitutes one of the cornerstones of our investigative efforts. Nevertheless, there must be times when each of us contemplates the usefulness of some of the studies that we order or perform. We wonder, for example, whether the assay is being handled correctly, and whether the test itself is relevant to the clinical problem at hand. Grace Centola recently set in motion an Androlog discussion to address these questions in assessing semen pH. A number of experienced clinicians and basic scientists joined the effort, and they have cast considerable light on this topic. In their own words, let's see what they had to say...
Dr Centola asked:
Does anyone still measure semen pH as part of routine semen analysis? We currently assess pH by using pH strips, but I am finding that the overwhelming majority of specimens have a pH of 8-8.5. According to World Health Organization (WHO) standards, the normal pH is at 7.2. Would anyone care to comment or offer suggestions on methods and the significance of measuring pH?
Clearly, Steven Schrader had been giving this matter some thought as well:
We find that the average pH is around 8.0. I cannot remember ever seeing a semen sample as low as 7.2. pH is sensitive to time since ejaculation. The older the semen sample. the higher the pH.
We use a pH meter, and have been discussing whether to continue to measure pH. I would like to hear the views of others on the importance and usefulness of semen pH measurements.
Juergen Liebermann indicated that he too had concerns regarding the WHO standard:
We measure semen pH as part of routine semen analysis by using pH strips, and have found that 75% of specimens have a pH of higher than 8.0 (average 8.2) in contrast to the WHO normal of 7.2 to 8.2. Measurement of pH should be done shortly after the specimen has liquified, because after liquefaction the equilibrium of the specimen changes and the pH increases with time. In addition, there is a positive correlation between pH and concentration of fructose!
Karen Seifarth reported better luck with this assay and provided some technical information:
We measure semen pH with pH strips from Microessential Laboratory, Brooklyn, NY, which are distributed through Allegience Healthcare. The name of the strips is pHydrion Microfine 6.0 to 8.0. The average pH range for our patients is 7.2 to 7.8. We check each batch of pH strips before use, using standard solutions (4.0, 7.0, and 10.0). We have not had any problems. The average pH of our specimens is probably about 7.4.
At this point, things really started to take shape! Rune Eliasson submitted the following contribution:
It is my impression that many laboratories still officially measure pH. One reason is that it is included as a standard method in the WHO manual on semen analysis. However, in a routine semen analysis, the pH of the seminal plasma does not contribute any information of value.
Dr Centola's observation is absolutely correct and so are her questions. Everyone who measures pH in seminal plasma is a victim of one of the many unscientific paradigms that strongly influence the performance and interpretation of semen analysis.
The "normal value" for the pH presented in the WHO manual is only one example of many unscientific statements in that document. In addition, the "normal" values have changed over the years from 7.2 to 7.8 in 1987, 7.2 to 8.0 in 1992, and 7.2 in 1999. There is no reference to any publication to motivate these changes.
When I started to work with human semen in 1961, I decided to start from scratch because it was obvious that almost everything published in the field was useless from a scientific point of view. The only person who published critical views on the methodology at that time (1964 to 1968) was Dr Matthew Freund, in the United States. I can recommend his articles for more than historical reasons.
In my laboratory, we needed only a few weeks of work in 1964 to understand that measurement of seminal pH did not give any information of value. I was one of the initial promoters of the first WHO manual on semen analysis (1980), and I convinced the other members of the editorial committee that pH measurements were useless. It was therefore not included in the first edition. In the preparation of the second edition, a majority of the editorial committee wanted pH to be included and I lost that vote. I was not involved in the third edition, but I was unable to remove pH measurements from the 4th edition of the WHO manual. It is always a problem when a scientific matter is decided by a majority vote, and only too often the prevailing opinion wins.
Those who still routinely measure the pH of seminal plasma should ask themselves why they do so, and then one hopes they would be aware of its zero value. Such a critical view of one's own routine analysis of semen could be an opening to a more critical view of many methods described in the WHO manual on semen analysis.
It would be an advantage to the science of andrology if more people followed Dr Centola's example and questioned recommended methods for pH, sperm count, sperm motility, and sperm morphology. If you are interested in more comments on the 4 editions of the WHO manual, Human Semen and Sperm-Cervical Mucus Interaction, I can send you a PDF file of a poster on this subject, which was presented at the first European Congress of Andrology in L'Aquila, Italy, in 2000.
Conversely, Robert Oates pointed out that in selected cases, assessment of semen pH may be clinically helpful:
In response to Grace Centola's question about semen pH and to Dr Eliasson's comments, semen pH can be an important part of an evaluation. As we all know, the alkalinity of the seminal fluid derives from the seminal vesicles, and acidity derives from the prostate. In evaluation of patients with azoospermia, the semen volume and pH are important for determining the differential. In low volume, acidic, azoospermic samples (volume 0.6cc, pH 6.5, for example), the differential is congenital bilateral absence of the vas deferens (CBAVD) or bilateral complete ejaculatory duct obstruction (EDO). A fructose assay is not needed because the volume coupled with pH indicates no contribution from the seminal vesicles. On the other hand, if the volume is normal and pH is alkaline, the seminal vesicles are functional and the ejaculatory ducts are patent (again, no need for fructose), and the differential includes spermatogenic failure or an obstruction at the level of the more proximal vas or epididymis—it does not include CBAVD or bilateral EDO. In cases in which pH is alkaline but the volume is low and azoospermic, the seminal vesicles are present and functional, and at least one ejaculatory duct is open. Palpation of the scrotal anatomy helps to clarify the exact etiology, whereas transrectal ultrasonography and hormonal assays may also help. Therefore, I agree with Dr Eliasson that pH is of no value when sperm are present in the semen (the ejaculatory ducts must be open), but I disagree in cases of azoospermia when attention to the details of semen volume and pH may be quite helpful in making the diagnosis. The "normal" pH is irrelevant. If laboratories want only to measure pH in cases of azoospermia, I think that would be just fine.
To this, Dr Eliasson replied:
In all clinical laboratory work, one should have a reason for an analysis. One must know what to look for, and one must know the relevant reference limits. A biochemical analysis can be used to investigate the functional capacity of an organ or to assist in the diagnostic work. pH in seminal plasma does not give any information on the functional status or capacity of the organs producing semen, nor is it equal to or better than any other method(s) for diagnosis of a disease or dysfunction in the reproductive organs, including "azoospermia."
That is why measurement of pH in the seminal plasma has no place in modern medicine. The various "reference limits" given in the three latest editions of the WHO Manual also support this view.
Trine Haugen provided additional technical information:
In my study, "pH of Human Semen" ( Int J Androl. 1998; 21 :105-108[Medline]), we used both a pH meter with a special electrode and pH paper, and measured 30 minutes and 60 minutes after ejaculation. Mean values were: meter (30 minutes) 8.2, paper (30 minutes) 8.4, meter (60 minutes) 8.3, paper (60 minutes) 8.5.
As the last comment in this discussion, Fernando Vasquez provided additional technical insight and some clinical correlation:
In our city, which is located at sea level on the coast, we have observed that pH, as measured in the laboratory, is alkaline (above 8.0), whereas other laboratories in noncoastal cities generally report pH values of 7.2-8.0. We thought the higher values may be caused by the pH strips (Spezialindikator; Merck). For that reason, we did a comparison between the pH meter and the strips, which gave results similar to those presented by Dr Trine B. Haugen. We have found that measurements given by the pH meter gave values that were lower than those of the strips. On many occasions, we have obtained high pH values that were associated with an increase in seminal viscosity. We now have the impression that the pH is associated with an inflammatory infectious process, and so has a clinical value in the functioning of the prostate and seminal vesicles.
Clearly, the topic of assessment of semen pH remains controversial. Still, this discussion brought out many helpful observations. Our thanks to all those involved for letting us "listen in" on this Androlog interaction.
This article has been cited by other articles:
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  D. H. Owen and D. F. Katz A Review of the Physical and Chemical Properties of Human Semen and the Formulation of a Semen Simulant J Androl, July 1, 2005; 26(4): 459 - 469. [Abstract] [Full Text] [PDF]
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