Clinical laboratory values in the aging population
Over the last decades the average life expectancy of the human race has increased significantly; however, little change has O C C U K ~ ~ in the maximum lifespan. Ofgreatest interest, however, is the functional lifespan. In this context, the clinical laboratory can play an important role by (a) defining proper reference ranges, (b) ident i ig disease processes early, and (c) aiding in the treatment process. We report on the study of laboratory values in the aging between 60 and 90 y, and those >90 y of age. Electrolytes (Na, K, C1, C02) are remarkably stable and deviate from the values in the young adults only in the very old (>90y). Total calcium and albumin values decrease, while ionized calcium shows little change. Phosphorus values decrease in males but only marginally in females. Serum urea nitrogen increases, especially in the >90-y-old, while creatinine remains unchanged due to the progressive decrease in muscle mass. Osmolality values increase. Prealbumin, albumin and transferrin increase, while al-antitrypsi retinol-binding protein and haptoglobin increase. Increases in glucose are accompanied by increases in insulin and C-peptide, except in the very old where the last two decrease. Total and HDLcholesterol increase; however, cholesterol in the very old is similar to that in young adults. T4, T3, thyroxine-binding globuhq testosterone, estrogens and progesterone decrease, but prolactin, luteinizing hormone and FSH increase sharply. Since antiquity the human race has had the desire to live a long life. Over the last few decades, there has been a sigtllficant increase in the average life expectancy due to a decrease in infant mortality and fatal diseases such as cardiovascular disease and cancer. In the USA, for example, the life expectancy has increased during this century fiom 47 to about 75 y. However, it is believed that we are approaching a maximum mean life expectancy. Even if we succeed in the elimination of all diseases that are the main contributors to death, the theoretical l i t has been calculated to be 85 y f an SD of 7 y. The observed increase in life expectancy will have a major impact on the world population. By the year 2020, the increase in the aging population is expected to be 159% in less-developed countries, 59% in developed countries and 69% in the USA. By 2050 the number of people >65 y world wide will be at least 2.5 billion. As a result, the traditional growth pyramid will soon be inverted with a narrow base and a broad tip. The spectrum of life expectancies in various countries of the world is wide, ranging from 41 y in Afghanistan to 75 and 82 y, respectively, for males and females in Japan. Women of all races live longer than men. For males, the higher mortality begins in the womb; the ratio of stillbirths for malexfemales is 1.4:l.