STABILITY OF FREE AND TOTAL PROSTATE SPECIFIC ANTIGEN IN SERUM FROM PATIENTS WITH PROSTATE CARCINOMA AND BENIGN HYPERPLASIA

Purpose

Instability of prostate specific antigen (PSA) in serum might complicate the interpretation of the free-to-total PSA ratio. We studied the in vitro stability of free PSA and total PSA in serum of patients with prostate cancer or benign prostate hyperplasia (BPH), and of elderly man without known prostate disease. Furthermore, we investigated conditions to stabilize the in vitro values in serum.

Materials and Methods

The effects of storage at 4C on free and total PSA were investigated in serum of 32 men with prostate cancer, 25 with BPH and 29 older than 70 years. All had total PSA less than 25 micro g./l. The influence of total PSA levels on in vitro changes in free-total PSA was studied in serum of 39 other prostate cancer patients (total PSA 1.7 to 298 micro g./l.). Stabilization studies were performed in yet another series of samples from 54 prostate cancer patients (total PSA 1.3 to 238 micro g./l.) by adjustment of serum pH to 5.5 before storage. Free and total PSA was measured by a commercial immunofluorometric assay, as well as by in-house immunofluorometric assays. Statistical analyses of the results were performed by analysis of variance with repeated measures.

Results

We found no difference between the results obtained by the 2 assay systems. After 7 days at 4C there was a slight decrease in total PSA in sera of prostate cancer patients, BPH patients and men older than 70 years. A decrease in mean free PSA values occurred in all groups (21.3, 15.7 and 14.6%, respectively). The decrease of free PSA with time was significant (p <0.0001) in all groups but there was no significant difference among the groups (p = 0.16). The concomitant decrease in free-to-total PSA ratio was significant in all groups (p <0.0001). This change was group dependent (p = 0.003), with the largest decrease in the prostate cancer group. Large interindividual differences were observed. Storage at 4C for 7 days of sera of 39 patients with localized and disseminated prostate cancer (total PSA 1.7 to 298 micro g./l.) gave a more pronounced decrease in free PSA than in total PSA. Adjustment of serum pH to 5.5 had a stabilizing effect on free PSA and on the free-to-total PSA ratio, giving a significantly smaller change in both values (p <0.0001).

Conclusions

In vitro instability of free PSA in serum and large interindividual differences should be considered when using the ratio of free-to-total PSA in evaluation of patients with suspected prostate cancer. Serum samples should be stored frozen if not analyzed immediately or acidified to pH 5.5. Interpretation of data from determination of free-to-total PSA ratio should be done with caution if the sampling and storage conditions are not known.     

PROSTATIC VOLUME AND RATIO OF FREE-TO-TOTAL PROSTATE SPECIFIC ANTIGEN IN PATIENTS WITH PROSTATIC CANCER OR BENIGN PROSTATIC HYPERPLASIA

Purpose

We correlated prostatic volume with the ratio of free-to-total prostate specific antigen (PSA) in serum from patients with prostatic cancer or benign prostatic hyperplasia (BPH) to evaluate how prostatic volume influences the ratio.

Materials and Methods

We evaluated sera from 395 patients (mean age 65 years, range 45 to 88) with prostate cancer (239) or BPH (156) for total PSA, free PSA and ratio of free-to-total PSA. For detection of total and free PSA we used an Immulite* free and total PSA assay. Prostatic volume was determined with transrectal ultrasonography. Prostatic volume in BPH and prostate cancer patients was divided into 10 ml. groups, and mean ratio of free-to-total PSA was calculated for each volume group and both diseases. For statistical analysis Mann-Whitney U and Kruskal-Wallis tests were performed in addition to calculation of sensitivity and specificity, and receiver operator curves for prostates 60 ml. or less and greater than 60 ml.

Results

For BPH patients the mean ratio of free-to-total PSA was 14.64 to 25.14% without a close relation to prostatic volume. In prostate cancer patients a proportional increase from 8.45 to 19.37% in the ratio of free-to-total PSA with volume was found. Mann-Whitney U analysis revealed significant differences in prostate cancer versus BPH only in patients with prostates of 60 ml. or smaller (p = 0.0008 to 0.029). No significant differences were seen when prostate cancer and BPH patients with prostates larger than 60 ml. were compared (p = 0.082 to 0.868). Kruskal-Wallis test confirmed independence of the ratio of free-to-total PSA from prostatic volume in BPH patients (p = 0.285) but dependence in prostate cancer patients (p <0.0001). Sensitivity was higher in patients with prostates 60 ml. or smaller (86.72%) than in patients with prostates larger than 60 ml. (66%), and specificity was lower at 45.78 and 56.16%, respectively.

Conclusions

We have shown that the ratio of free-to-total PSA is influenced by prostatic volume in patients with prostate cancer. The ratio of free-to-total PSA provides useful information for differentiate BPH from prostate cancer in patients with small prostates but it is less useful in patients with larger prostates, probably because of the larger proportion of benign hypertrophic tissue.     

SERUM FREE PROSTATE SPECIFIC ANTIGEN AND PROSTATE SPECIFIC ANTIGEN DENSITY MEASUREMENTS FOR PREDICTING CANCER IN MEN WITH PRIOR NEGATIVE PROSTATIC BIOPSIES

Purpose

We examined the usefulness of measurements of free prostate specific antigen (PSA) and PSA density for predicting prostate cancer in men who had had a prior negative biopsy, a serum PSA level of 4.1 to 10.0 ng./ml. and benign findings on prostate examination.

Materials and Methods

We measured percent free serum PSA and PSA density in 163 male volunteers age 50 years or older who were advised to have repeat prostatic biopsies for a serum PSA level of 4.1 to 10.0 ng./ml.

Results

Of 99 men who had repeat biopsies 20 (20%) had prostate cancer detected. Prostate cancer was significantly associated with lower free PSA level and higher PSA density, with overlap in 83% of the cases. The use of percent free PSA cutoffs of 28 and 30% would have detected 90 and 95% of cancers, respectively, and avoided 13 and 12% of the biopsies, respectively. PSA density cutoffs of 0.10 and 0.08 would have detected 90 and 95% of cancers, respectively, and avoided 31 and 12% of biopsies, respectively.

Conclusions

Free PSA and PSA density predict prostate cancer in men who have had prior negative prostatic biopsies, serum PSA levels of 4.1 to 10.0 ng./ml. and a benign prostate examination. Both parameters may be used to avoid unnecessary biopsies with an acceptable decrease in sensitivity. Further studies are needed to determine cutoffs to be used in clinical practice.     

THE EFFECT OF HIGH GRADE PROSTATIC INTRAEPITHELIAL NEOPLASIA ON SERUM TOTAL AND PERCENTAGE OF FREE PROSTATE SPECIFIC ANTIGEN LEVELS

PURPOSE: It is established that the percentage of free prostate specific antigen (PSA) in serum is low in patients with prostate cancer. An unanswered question is whether a low percentage of free PSA can be explained by high grade prostatic intraepithelial neoplasia alone. We compared the percentage of free PSA in men with high grade prostatic intraepithelial neoplasia alone, prostate cancer, benign prostatic hyperplasia (BPH) and a normal prostate (that is normal digital rectal examination and PSA less than or equal to 2.5 ng./ml.). MATERIALS AND METHODS: From October 1994 through December 1997, 48 men were diagnosed with high grade prostatic intraepithelial neoplasia without concomitant prostate cancer. Of these men 43 with a mean age plus or minus standard deviation of 67.4 +/- 7.8 years comprised our study group. To date none has been diagnosed with cancer during followup. Serum free and total PSA levels were measured, and the percentage of free PSA was calculated. The percentage of free PSA in the 43 men was compared to that in 50 with prostate cancer (mean age 65.4 +/- 7.8 years), 50 with biopsy proved BPH (67 +/- 7) and 43 with a normal prostate (61 +/- 8). RESULTS: There was no significant difference in mean total serum PSA in patients with high grade prostatic intraepithelial neoplasia, prostate cancer or BPH. The percentage of free PSA was significantly lower in patients with prostate cancer (14.9 +/- 6.5%) than those with high grade prostatic intraepithelial neoplasia (20.8 +/- 7.1%), BPH (20.1 +/- 7.3%) or a normal prostate (27.7 +/- 12.2%). There was also no significant difference in the percentage of free PSA between men with high grade prostatic intraepithelial neoplasia (20.8 +/- 7.1%) and those with BPH (20.1 +/- 7.3%). Additionally, men with a normal prostate had a higher percentage of free PSA (27.7%) than those with BPH (20.1%), high grade prostatic intraepithelial neoplasia (20.8%) or prostate cancer (14.9%). CONCLUSIONS: The percentages of free PSA in men with high grade prostatic intraepithelial neoplasia and BPH are similar, and significantly higher than those found in men with prostate cancer.     

THE EFFECT OF FINASTERIDE ON PROSTATE VOLUME,URINARY FLOW RATE AND SYMPTOM SCORE IN MEN WITH BENIGN PROSTATIC HYPERPLASIA

This study was designed to determine the efficacy of the 5α-reductase inhibitor finasteride (Proscar, MK-906) in men with reduced urinary flow rates and symptoms of urinary outflow obstruction secondary to benign prostatic hyperplasia. Forty-five men were randomized to one of three groups receiving either placebo, 1 mg/day or 5 mg/day tinasteride for the first 12 months of the study period. At the end of this period all men received 5 mg/day finasteride for a further 2 years. Efficacy was determined by measurement of prostate volume, maximum urinary flow rate, and symptom score using a modified Boyarsky assessment. Prostate volume reduced by 20 and 27%. respectively, for those on 1 and 5 mg after the first year. At 3 years the volume had reduced by 43%. This reduction in prostate volume was associated with an improvement in maximum urinary flow rate by 50% (1 mg), and 35% (5 mg) at 1 year, and 36% at 3 years. The total, obstructive and non-obstructive symptom scores decreased (improved) for patients on 1 and 5 mg tinasteride, with the total score reducing by 33% from baseline at year 3. The results demonstrate that finasteride causes a modest but signiticant clinical improvement in men with urinary outflow obstruction secondary to benign prostatic hyperplasia.     

EFFECT OF EXOGENOUS TESTOSTERONE ON PROSTATE VOLUME, SERUM AND SEMEN PROSTATE SPECIFIC ANTIGEN LEVELS IN HEALTHY YOUNG MEN

Purpose

We investigate and define the effects of exogenous testosterone on the normal prostate.

Materials and Methods

A total of 31 healthy volunteers 21 to 39 years old were randomized to receive either 100, 250 or 500 mg. testosterone via intramuscular injection once a week for 15 weeks. Baseline measurements of serum testosterone, free testosterone and prostate specific antigen (PSA) were taken at week 1. Semen samples were also collected for PSA content and prostate volumes were determined by transrectal ultrasound before testosterone injection. Blood was then drawn every other week before each testosterone injection for the 15 weeks, every other week thereafter until week 28 and again at week 40. After the first 15 weeks semen samples were again collected, and prostate volumes were determined by repeat transrectal ultrasound.

Results

Free and total serum testosterone levels increased significantly in the 250 and 500 mg. dose groups. No significant change occurred in the prostate volume or serum PSA levels at any dose of exogenous testosterone. Total semen PSA levels decreased following administration of testosterone but did not reach statistical significance.

Conclusions

Despite significant elevations in serum total and free testosterone, healthy young men do not demonstrate increased serum or semen PSA levels, or increased prostate volume in response to exogenous testosterone injections.     

STABILITY OF SERUM TOTAL AND FREE PROSTATE SPECIFIC ANTIGEN UNDER VARYING STORAGE INTERVALS AND TEMPERATURES

Purpose

Measurement of total serum prostate specific antigen (PSA) is widely used as an aid to early detection of prostate cancer. Measurement of the ratio of free-to-total PSA (percentage of free PSA) may help increase specificity of PSA testing. We prospectively studied the effects of varying the storage temperature and interval on total and free PSA levels.

Materials and Methods

We measured the baseline total and free serum PSA levels in 36 volunteers (mean age 66 years) and then retested aliquots of these serum samples after varying storage intervals (24 hours, 2 weeks and 9 months) at 3 different temperatures (4C, −20C and −70C). Volunteers represented a spectrum of prostatic conditions (PSA levels 2.0 to 4.0 ng./ml., PSA levels greater than 4.0 ng./ml. without cancer and PSA levels greater than 2.0 ng./ml. with prostate cancer). We used repeated measures analysis of variance to test for changes in total and free PSA levels as a function of time and temperature. We also evaluated the impact of storage at different temperatures and times on the percentage of free PSA.

Results

Across groups total and free serum PSA decreased from the baseline level differentially as a function of longer storage interval and higher temperature (p <0.05). No significant difference was found for change in total PSA at 24 hours, 2 weeks or 9 months for storage temperatures of −20C compared with −70C. A significant change from baseline level was found for free PSA when stored in −20C compared with −70C for 2 weeks but the magnitude of the change was modest.

Conclusions

For storage intervals up to 9 months total PSA is more stable than free PSA under temperature conditions ranging from 4C to −70C. This differential stability has important implications for the clinical evaluation of percentage of free PSA to distinguish between benign and malignant diseases of the prostate.     

INDUCTION OF PROSTATE APOPTOSIS BY DOXAZOSIN IN BENIGN PROSTATIC HYPERPLASIA

Purpose

The molecular mechanisms underlying the therapeutic effect of the alpha 1 blocker, doxazosin, on benign prostatic hyperplasia (BPH) are poorly understood. We evaluated the effect of doxazosin on cell proliferation and apoptosis in the prostatic glandular epithelium and stroma of patients with BPH.

Materials and Methods

We examined proliferative and apoptotic activities in prostate specimens of 22 men a mean of 65 years old with BPH before and after doxazosin treatment within the normal therapeutic range. Proliferative and apoptotic indexes were determined using Ki-67 nuclear antigen staining and the terminal transferase end labeling assay, respectively. The smooth muscle cell content in prostatic specimens was identified by smooth muscle alpha-actin, and desmin immunoreactivity and apoptotic indexes were correlated with prostatic stromal tissue regression and improvement in BPH symptoms.

Results

In response to doxazosin treatment there were no significant changes in the kinetics of cell proliferation in the prostatic epithelial or stromal cell population. Mean pretreatment baseline apoptosis was 1.9 and 1.0% for the epithelial and stromal prostate components, respectively. Mean apoptotic indexes significantly increased after 3 months of doxazosin treatment in the glandular epithelial (6%) and smooth muscle cells (15%). By 12 months after treatment epithelial apoptosis had decreased to constitutive levels, while the apoptotic index of prostatic stroma cells remained high. Doxazosin induced smooth muscle cell apoptosis correlated with prostatic stromal degeneration, decreased alpha-smooth muscle actin expression and improved BPH symptoms.

Conclusions

These findings implicate the induction of prostate apoptosis by doxazosin as a potential molecular mechanism underlying the acute and chronic therapeutic responses of BPH to alpha 1 blockade.     

ALTERATIONS IN GAP JUNCTION PROTEIN EXPRESSION IN HUMAN BENIGN PROSTATIC HYPERPLASIA AND PROSTATE CANCER

PURPOSE: Gap junctions composed of connexin proteins have an essential role in intercellular communication and differentiation. Dysregulation of connexin expression is believed to have a role in carcinogenesis. The human prostate has been reported to express connexin 32 and 43. However, the expression pattern in prostate cancer is controversial, while to our knowledge connexin expression has not been reported in benign prostatic hyperplasia (BPH). To understand the potential involvement in prostate disease connexin 32 and 43 expression was evaluated in a series of normal prostate, BPH and prostate cancer specimens that were surgically removed due to bladder outlet obstruction. MATERIALS AND METHODS: Frozen sections of 23 normal, 43 BPH and 40 cancer involved prostates were evaluated for the presence, staining intensity and pattern of connexin 32 and 43 by immunocytochemical testing. RESULTS: In all specimens examined connexin 43 stain was punctate along the borders of the basal epithelial cells, whereas connexin 32 immunolocalized to luminal epithelial cells. In normal prostate connexin 43 and 32 were present in 87% and 65% of specimens, respectively, at low to moderate stain intensity. Importantly none of the normal samples were negative foreach connexin. In BPH specimens there was a marked increase in the incidence and intensity of connexin 43 and 32 immunostaining within epithelial cells. In addition, 23% of BPH samples showed strong connexin 43 expression in stromal cells. In contrast, connexin was decreased in prostate cancer specimens, of which 65% and 38% were negative for connexin 43 and 32, respectively, and 28% were negative for each type. In poorly differentiated tumors connexin 43 and 32 were present in only 10% and 40% of tumors, respectively, at low immunostaining intensity. CONCLUSIONS: In normal human prostate basal cells communicate via connexin 43 gap junctions, whereas luminal cells communicate via connexin 32 gap junctions. In BPH gap junctional intercellular communication is increased in epithelial and stromal cells, which may have a role in BPH pathogenesis. In prostate cancer gap junctional intercellular communication is decreased, is as indicated by decreased expression of connexin 43 and 32 with severe loss in poorly differentiated prostate cancer. These alterations in connexin expression may have a role in dedifferentiation and tumor progression.     

PREVALENCE OF BENIGN PROSTATIC HYPERPLASIA IN SPANISH MEN 40 YEARS OLD OR OLDER

Purpose

We estimate the prevalence of benign prostatic hyperplasia (BPH) according to symptoms as well as prostate obstruction determined by uroflowmetry and prostate size.

Materials and Methods

A cross-sectional study was performed at the autonomous community of Andalusia in 1,106 men 40 years old or older. The International Prostate Symptom Score (I-PSS) questionnaire was used to establish symptoms, abdominal and transrectal ultrasonography was done to measure prostate size and uroflowmetry was performed to measure urinary flow obstruction.

Results

The prevalence of moderate or severe symptoms was 24.94% and it increased with age. Of the 1,106 subjects 4.19% had severe prostatism, while 12.45% had poor quality of life (I-PSS greater than 3). Average prostate size was greater than 30 gm. in men 60 years old or older. Maximum urine flow was less than 10 and 15 ml. per second in 25.97 and 55.67% of the men, respectively. The prevalence of BPH, defined as I-PSS greater than 7, maximum flow less than 15 ml. per second and prostate size greater than 30 gm., was 11.77% (range 0.75 to 30 at ages 40 to 49 and greater than 70 years, respectively).

Conclusions

The prevalence of BPH increases with age. Moderate prostatism is perceived as resulting in poor quality of life by young subjects and good quality of life by some older subjects. In some men there were symptoms and obstruction but no prostate enlargement. This percentage persists with age after 50 years, when the prevalence of BPH starts to increase.     

SERUM HETEROPHILE ANTIBODIES INTERFERE WITH PROSTATE SPECIFIC ANTIGEN TEST AND RESULT IN OVER TREATMENT IN A PATIENT WITH PROSTATE CANCER

PURPOSE: We evaluated how naturally occurring heterophile antibodies in patient serum interfered with prostate specific antigen (PSA) immunoassay, resulting in over treatment for prostate cancer. MATERIALS AND METHODS: Serum samples were treated with heterophilic blocking reagent (Scantibodies Laboratory, Inc., Santee, California). Treated and untreated samples were tested by the Medics (Tosoh, Foster City, California ) Tandem-R (Beckman-Coulter Inc., Chaska, Minnesota) and Elecsys (Roche Molecular Biochemical, Indianapolis, Indiana) PSA assays. Heterophile antibodies were measured directly in treated and untreated samples by the human anti-mouse antibody immunoradiometric assay and heterophilic antibody identification enzyme immunoassay (Scantibodies Laboratories, Inc.). RESULTS: Human anti-mouse Ig heterophile antibodies in patient serum caused false-positive PSA test findings after radical prostatectomy, resulting in over treatment for presumed disease recurrence. CONCLUSIONS: If PSA is detectable after radical prostatectomy and the likelihood of incomplete resection or systemic disease is low, the presence of heterophile antibodies should be considered.     

RATIO OF FREE-TO-TOTAL PROSTATE SPECIFIC ANTIGEN IN SERUM CANNOT DISTINGUISH PATIENTS WITH PROSTATE CANCER FROM THOSE WITH CHRONIC INFLAMMATION OF THE PROSTATE

Purpose

We demonstrate the effect of chronic inflammation of the prostate on the ratio of free-to-total prostate specific antigen (PSA) in serum calculated as a percentage of free PSA and, therefore, that percentage of free PSA is an unspecific means to distinguish among prostate cancer, chronic prostatitis and benign prostatic hyperplasia (BPH).

Materials and Methods

Total, free and percentage of free PSA was measured in 66 men with prostate cancer, 119 with BPH and 17 with asymptomatic chronic prostatitis. In all patients the diagnosis was histopathologically confirmed by microscopic examination of prostatic specimens after sextant biopsy, transurethral prostatic resection or prostatectomy.

Results

The median values of total, free and percentage of free PSA were 4.11 micro g./l., 0.75 micro g./l. and 20.4% in patients with BPH, 10.0 micro g./l., 0.84 micro g./l. and 8.5% in those with prostate cancer, and 7.60 micro g./l., 1.23 micro g./l. and 10.6% in those with chronic prostatitis. Patients with prostate cancer and chronic prostatitis had a significantly lower percentage of free PSA than those with BPH. Receiver operating characteristics curve analysis showed that percentage of free PSA as a discriminator between prostate cancer and BPH was not suitable for differentiating between prostate cancer and chronic prostatitis.

Conclusions

Chronic prostatitis is not characterized by elevated total PSA concentrations alone but also by a decreased percentage of free PSA, a tendency similar to that in prostate cancer. This unspecific change in percentage of free PSA must be considered to interpret the percentage of free PSA correctly.     

肿瘤标志物TSGF及CEA对肿瘤的诊断价值探讨

目的 比较恶性瘤特异性生长因子（TSGF）和癌胚抗原（CEA）在肿瘤诊断中的价值。方法 将患者分成恶性肿瘤组和非恶性肿瘤组两组,非恶性肿瘤又可分为炎症组和非炎症组;检测各组血清TSGF及CEA水平。结果 TSGF和CEA在恶性肿瘤、非恶性肿瘤、炎症及非炎症组中的阳性检出率分别为67．41％和38．84％、24．56％和2．63％、32．35％和5．88％及18．25％和0％,二者在恶性肿瘤组中的阳性率明显高于其它组（P＜0．005）;在恶性肿瘤组中,TS－GF的阳性率高于CEA（P＜0．005）。结论 血清TSGF的检测为我们提供了一个较好的肿瘤检测手段,它具有敏感性高及广谱性的优点。CEA对肿瘤检测的特异性较TSGF高。两者联合检测可提高肿瘤的诊断率。     

SERIAL PROSTATE SPECIFIC ANTIGEN, FREE-TO-TOTAL PROSTATE SPECIFIC ANTIGEN RATIO AND COMPLEXED PROSTATE SPECIFIC ANTIGEN FOR THE DIAGNOSIS OF PROSTATE CANCER

Purpose: The free-to-total prostate specific antigen (PSA) ratio and complexed PSA have been introduced as adjuncts to total PSA for prostate cancer screening. Little data exist on the use of these tests for serial PSA screening. We compared serial total PSA, the free-to-total PSA ratio and calculated complexed PSA in men diagnosed with prostate cancer and matched controls in a population based study.Materials and Methods: We identified 90 men diagnosed with prostate cancer between 1988 and 1996 with at least 3 serial serum samples obtained at 2-year intervals who were participants in the beta-Carotene and Retinol Efficacy Trial for the prevention of lung cancer. Samples were available up to 10 years before diagnosis. A total of 90 age matched men from the same cohort without prostate carcinoma were identified as controls. Free and total PSA was measured by the Abbott AxSYM system.Results: Baseline demographics of cases and controls were similar. At baseline and diagnosis the men with prostate cancer had higher total and complexed PSA, and a lower free-to-total PSA ratio than controls. Mean followup was 5.2 years in cases and 5.5 in controls. The yearly change in PSA parameters in cases versus controls was 20.7% versus 3.5% for total, -3.4% versus 0.2% for free-to-total and 21.5% versus 3.4% for complexed PSA (p <0.0001). At diagnosis PSA alone was estimated to perform with more than 90% specificity in our model.Conclusions: In this population based study total PSA was superior to the free-to-total PSA ratio for predicting the development of prostate cancer. While serial changes in free-to-total PSA ratios with time were statistically significantly different in men diagnosed with prostate cancer and controls, the magnitude of these serial changes were slight enough to render them clinically insignificant.     

SERUM ESTRADIOL LEVELS IN NORMAL MEN AND MEN WITH IDIOPATHIC INFERTILITY

Serum estradiol levels were measured in 360 men attending an infertility clinic and 68 proven fertile men to determine whether estradiol measurements are clinically useful. The normal range of estradiol levels found in fertile men was 10–82 pg/ml. Serum concentrations of estradiol in azoospermic or oligozoospermic patients were significantly lower than those in normozoospermic men (p < 0.021). Serum concentrations of testosterone were also significantly decreased in infertile patients (p < 0.025). This decrease in serum estradiol may be partly due to reduced testosterone levels in these men because estradiol is mainly formed by peripheral aromatization of testosterone in fatty and muscle tissues. However, the exact mechanism for the decrease in the serum estradiol levels remains undetermined. It is concluded that serum estradiol levels are significantly low in the men with various testicular disorders.