Age-specific reference ranges of serum prostate-specific antigen in Iraqi men

Abstract

Background: Different races have their own reference ranges of serum prostate-specific antigen (PSA) because of the influence of geographical and ethnic differences. In this study we determined the distribution of serum PSA levels in Iraqi men with no prostate cancer, to our knowledge the first such study from Iraq.

Subjects and methods: From January 2003 to May 2004, in a prospectively designed study, we included 130 Iraqi men aged 20-79 years. The criteria of an elevated PSA level, abnormal ultrasonography results and/or abnormal findings on a digital rectal examination were used to exclude patients from the study. Ethnicity was not recorded, as Iraq has a multi-ethnic status. The results were analysed using descriptive statistics, statistical tables, the arithmetic mean, standard error, standard deviation, and by two extremes.

Results: The PSA values in different age groups (20-29, 30-39, 40-49, 50-59 and 60-79) were, respectively, ⩾0.55 to ⩽1.3, ⩽1.6, ⩽2.0, ⩽4.6 and ⩽4.8 ng/mL. There was a significant increase between the third and fourth group, and all these results were significant at P < 0.001, with the last being more significant.

Conclusion: Serum PSA measurements should be standardized according to country and ethnic groups. Our result of a PSA maximum at 4.8 ng/mL is slightly more than the international standard threshold of 4.0 ng/mL.

Keywords: Age; Iraqis; Prostate cancer; Prostate-specific antigen; ROC, receiver operating characteristic; TAUS, transabdominal ultrasonography.

Figure 1

Increment in PSA with age.

Figure 2

Changes in PSA related to each age group shows the mean, upper and lower bound of the mean and upper and lower bound of extremes of PSA.

Figure 3

Receiver operating curve.

Figure 4

Correlation between age and PSA by long-term trend.