Prostate-specific antigen
Posted by admin on October 13th, 2008Prostate-specific antigen (PSA) levels rise with age; the levels are typically about 2.5 ng/mL in men 40 to 49 yr of age, increasing to about 6.5 ng/mL by age 70 to 79. PSA levels may increase as a result of conditions other than cancer, such as benign prostatic hyperplasia or a prostatic infection, or briefly as a result of prostatic manipulation.
Age per se has no influence on the erythrocyte sedimentation rate (ESR). The sensitivity of an ESR > 20 mm/h in identifying the presence of a clinical disorder is 0.55; however, the specificity is 0.96, and the positive predictive value of an elevated ESR being associated with a clinical disorder is 0.93. Monoclonal gammopathy or elevated fibrinogen level, as well as more common chronic inflammatory diseases, can be a cause of elevated ESR in patients having no other obvious cause. The influence of plasma fibrinogen, total protein, serum globulins, and immunoglobulins on the ESR in older persons is similar to that in younger adults. Therefore, any age-related changes in ESR are best explained by disease rather than by aging itself. Severe anemia or hypo-albuminemia limits the test’s usefulness.
A study using agarose gel electrophoresis and immunofixation demonstrated a 10% incidence of monoclonal gammopathy in apparently healthy persons ranging in age from 62 to 95 yr. The incidence is 6% in persons < 80 yr and 14% to 19% in those > 90 yr. An unexplained ESR elevation in the elderly warrants investigation for a monoclonal gammopathy, which occurs in about 35% of such persons. These gammopa-thies may indicate a dysregulation of the immune system occurring with age (ie, impaired T-cell or B-cell function).
Serum levels of the major subsets of immunoglobulins (IgG, IgM, and IgA) do not show clinically significant changes with age. A decline in several T-cell functions is the most consistent age-related change in the immune system.
Tags: antigen
