LABORATORY TESTING OVERVIEW

The preliminary laboratory examination performed by the primary care physician should include two properly collected and analyzed semen samples and the evaluation of serum follicle-stimulating hormone (FSH) levels. The importance of proper specimen collection and analysis by a laboratory that has demonstrated quality control in evaluating semen samples and performs at least 20 analyses per week cannot be overemphasized. Abnormalities in the semen samples (see Table 3) or an elevated FSH suggesting intrinsic testicular failure with compensatory increase in FSH production by the pituitary suggest the need for prompt urologic referral.

Semen Analysis

Semen should be collected for analysis after 48 to 72 hours of abstinence. Ideally, it should be collected at the laboratory by masturbation into a container furnished by the laboratory that has been tested to ensure that it will not alter the sperm sample's quality. The specimen should be analyzed within l hour and kept at body temperature before analysis in order to ensure accuracy of the evaluation. A minimum of two samples should be obtained. To decrease variability, each sample should be collected after the same period of sexual abstinence (2 to 3 days).

Characteristics analyzed are semen volume, sperm density, sperm motility, forward progression, and sperm morphology. In addition, the sample is analyzed for the presence of leukocytes that might indicate infection or inflammation

An aliquot of the sample is air-dried on a slide and stained for determination of sperm shape or morphology. Normal semen samples contain at least 50% morphologically normal sperm. Increased numbers of abnormally shaped sperm are indicative of testicular stress (e.g., varicocele, poor sperm production, environmental toxins, etc.).

Table 3 illustrates the generally accepted limits of adequacy, but it should be noted that the laboratory analysis does not predict fertility and that pregnancy is the only irrefutable proof of the sperm's capability to fertilize.

Further tests of sperm physiology might include the measurement of antisperm antibodies (ASA), a sperm-cervical mucus interaction test, determination of strict sperm morphology, and the sperm penetration test. However, these more complicated assays generally are left to a specialist in male reproductive disorders.

TABLE 3.
Normal Values of Semen Variables: WHO Guidelines.

From: WHO Laboratory Manual for the Examination of Human Semen and Sperm-Cervical Mucus Interaction. Third Edition. Cambridge University Press, 1992, p 44.

Hormonal Evaluation (see Table 4)

The incidence of primary endocrine defects in infertile men is less than 3%, and it is rare in men whose sperm concentration is greater than 5 x 10⁶/mL. However, when an endocrinopathy is suspected, specific hormonal treatment is often successful. Therefore, a hormone evaluation should be performed when the sperm concentration is low, or when an endocrinopathy is suspected clinically. This testing can be initiated by the primary care physician or can be handled entirely by a urologist.

A markedly elevated serum FSH usually is associated with azoospermia or severe oligospermia and usually indicates a difficult-to-treat germ cell defect (primary testicular failure). A very low or nondetectable FSH indicates hypogonadotropic hypogonadism, this diagnosis being suggested clinically by undermasculinization. When correlated with concomitantly decreased levels of serum testosterone and luteinizing hormone (LH), the diagnosis is confirmed, and appropriate treatment should be initiated under the direction of a urologist or endocrinologist. A year of hormone therapy may be required before optimal sperm production is reached. Because hyperprolactinemia has also been reported to cause oligospermia, serum prolactin should be measured when a patient has a low serum testosterone level without an associated increase in LH, as well as symptoms of decreased libido, decreased ejaculate volume, and especially with galactorrhea.

TABLE 4.
Usual Findings of Hormonal Status Correlated to Clinical Diagnosis.