To estimate the lower limits of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH), we examined data from 988 samples with C-reactive protein levels of 0.0mg/ dl. Samples were obtained from 400 40-59-year-old Japanese females who consulted our institute for health screening between April 2007 and March 2011. At a serum iron value over 90μg/dl level, the hemoglobin concentration, MCV and MCH were 13.6±0.8 g/dl, 91.3±3.6fl and 30.2±1.4pg, respectively. Compared to those at a serum iron level over 90μg/dl level, the serum iron levels relative to hemoglobin concentration, MCV and MCH significantly decreased to 65-74μg/dl (hemoglobin concentration; 13.0±0.9 g/dl, p=3.3E-05), 65-74μg/dl (MCV; 89.1±6.1fl, p=2.8E-04), 75-84μg/ dl (MCH; 29.5±1.7pg, p=1.4E-04), respectively. At a serum iron level of 35-44μg/dl, hemoglobin concentration, MCV and MCH were 12.0±1.0 g/dl, 83.8±5.7fl and 26.7±2.3pg, respectively. We performed multiple regression analyses of the serum iron levels using hemoglobin concentration and MCV or MCH as explanatory variables. We estimated the serum iron level of the sampling data, which showed serum iron level over 90μg/dl, using two different regression formulae. When the estimated serum iron level was within normal limits and the hemoglobin concentration was 12.0 g/ dl, the lower limits of MCV and MCH were calculated as 88.9fl and 29.0pg, respectively, and when the hemoglobin concentration was 12.8 g/dl, the lower limits of MCV and MCH were calculated as 84.8fl and 27.9pg, respectively. Therefore, we should evaluate a 40-59-year-old female for anemia when MCV ≤ 90fl and/or MCH ≤ 29pg, indicating microcytic anemia.

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 Laboratory tests are used for diagnosis, treatment, and prognostic evaluation of diseases; however, the reference values used are obtained from populations. Therefore, abnormal changes tend to be overlooked when the changes are small, or detailed examinations tend to be recommended in excess when laboratory values exceed the reference values on health check-ups and so on. In this study, we obtained individually-based reference values from consecutive laboratory tests and examined whether subtle changes could be detected. The results suggest that the use of individuallybased reference values would allow the detection of abnormalities not detectable when populationbased reference values are used; thus, we consider individually-based reference values to be more useful in making judgments than population-based reference values. The prerequisite for obtaining individually-based reference values is to obtain consecutive laboratory values using the same measurement methods. In fact, however, laboratory tests are usually performed at different facilities, making it impossible to perform these tests uniformly. In order to calculate individually-based reference values based on consecutive laboratory test values properly, we believe it is necessary, in addition to internal accuracy control or the external accuracy control review currently performed at participating individual facilities, to ensure laboratory values by obtaining ISO15189 and to provide more stable laboratory values.

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 The aim of this article is to explain the reason why PSA screening is necessary in Japan now. In regard to the number of patients, prostate cancer is the most prevalent cancer in male Japanese now. More than 10,000 Japanese men are dying of prostate cancer annually and the incidence and mortality rates of prostate cancer are rapidly increasing. In contrast, a marked earlier stage-migration of newly diagnosed prostate cancer and a steady decrease in prostate cancer mortality rate in the recent consecutive 15 years are noted in USA where PSA screening is much more prevalent than in Japan. A large-scale prospective randomized trial in EU has revealed that PSA screening does decrease prostate cancer mortality up to 20%. This life-saving effect of PSA screening can be enjoyed also in Japan because PSA exposure rate in Japanese male population remains quite low.
 Without sufficient PSA screening, advanced stage prostate cancers are being diagnosed in nonnegligible number of Japanese men. Therefore, the optimal process of prostate cancer management in Japan can be summarized as to diagnose clinically significant prostate cancer within a curative window, to evaluate risk of prostate cancer precisely and to select proper treatment. To achieve this optimal management process, diagnostic process of prostate cancer should meet the following criteria: i) Propagation of efficient PSA screening program, ii) Decision of precise indication of prostate biopsy and iii) prostate biopsy method with optimal diagnostic ability. To stop the steady increase in prostate cancer mortality rate in Japan, item i) is essential. To make the PSA screening fruitful, item ii) and iii) are mandatory.

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