Full blood count is a frequently used laboratory test performed to support the diagnosis of several diseases; anaemia, certain cancers, infections, acute hemorrhagic states, allergies and immunodeficiency disorders or used in periodic health examination and preoperative evaluation (1). Reference values of full blood count have been determined in several trials but we could not find reports on reference values of full blood count parameters in Anatolia. Interpretation of haematological parameters by physicians with reference values produced from the population living in this region would provide a unified standard. Social, nutritional, and environmental factors together with age, sex, body build, ethnic background and altitude are also required to get a unified standard (2,3). Variances among populations are widely contributed to genetic factors and the minimum number of subjects needed to determine precisely the lower and upper limits of reference values is quite large (4).

The present study was conducted to determine the reference values of haematological parameters in healthy Anatolian males who are 18-45 years old and living at the same altitude (1050m) in similar socio-economical and environmental conditions. These references than can be used in clinical laboratories to interpret test results

Materials Methods

Subjects and blood analysis procedure

Males who were 18-45 years old and living in Anatolia were recruited in this study. Physical examination was performed with routine biochemical (Fasting blood glucose, renal and hepatic function tests), full blood count and urinary analysis. Venous blood sampling was drawn from the antecubital vein into 3 ml tubes containing K3EDTA anticoagulant with Terumo venoject. Blood samples were kept at room temperature and tested in one-hour time. Blood analysis was processed using the Coulter Counter ZF6 to determine hemoglobin (Hb), hematocrit (Hct) and red cell indices as mean cell volume (MCV), mean cell hemoglobin (MCH), and mean cell hemoglobin concentration (MCHC) and red cell distribution width (RDW). Reference values of full blood count parameters were defined for values between 2,5-97,5 percentiles in 95% confidence limits. Subjects were all healthy males living in Anatolia who attended for check-up and they live at the mean altitude of 1050m. Subject's previous diseases, operations, dietary habits and blood donation in the previous six months were investigated.

Statistical Analysis

Distribution of data was abnormal for normal or lognormal distribution for age so medians were used for analysis. Power analysis was performed to determine the number of subjects required for this study. Correlation analysis was performed to obtain the relationship between age, BMI and full blood count erythrocyte indices.

Distribution of collected data was abnormal for normal or lognormal distribution for age so medians were used in analysis. In 95% confidence limits and significance level of 0.05 (two-sided) 99 percent power was maintained if at least 481 subjects were enrolled according to MCV, which has the greatest standard deviation. Full blood count values of 530 healthy males who were 18-45 years old were determined. Subjects mean age was 26,23±6,26 (range: 18-45) years and mean body mass index (BMI) was 23,46±2,64 (range: 17,20-28,60). On the base of physical examination, blood and urine analysis; subjects were accepted as healthy. There was no correlation between age, red blood cell count, haemoglobin, hematocrit, MCV, MCH, MCHC, RDW values. Correlation between age and BMI was weak and positive (p>0,01).
Subjects own and coulter reference values for Hb, Hct and red cell indices were then compared and reference value of MCH was found to be similar (p>0,05) but all other indices and Hb, Hct reference values were significantly different from each other (Table I). White blood cell counts of subjects were under reference values in 1,1%, in normal reference value in 94,3% and over reference value in 4,5%. White blood cell counts differential analysis was in favour of lymphocytes so they were considered to be viral infections. Subjects were divided into three age groups (18-24, 25-34, 35-45) and their percentiles of BMI, Hb and Hct were given in Figures1, 2, 3, 4. Percentiles of 2,5, 5, 10, 25, 50, 75, 90, 95, 97,5 of RBC, Hb, Hct, MCV, MCH, MCHC, RDW were shown in Table II. Main geographical factors in this region during the study period were noted as follows; annual daily sunshine was 6.41 hours, humidity was 64.0% and temperature was 10.3 oC.

This paper provides reference values for full blood count parameters of Hb, Hct, MCV, MCH, MCHC and RDW of healthy Anatolian males who were 18-45 years old. In this study group subjects' body mass indexes were covering the lean (<20: 10%), normal (20-24,9: 59,2%) and overweight (25-29,9: 30,8%) values mentioned for our population (5). National Centre for Health Statistics of United States currently uses the 85th percentile of BMI for persons aged 20-29 as >27,8 as less severe obese. Subjects enrolled in this study were all in normal value, in less severe obese value, or lean. This limits our contribution on an overweight population.
There were significant differences detected in reference values of full blood counts in adult population (3,6,7). Characteristics of subjects, analytical methods and methods of calculation all may contribute to differences in reference values. Hemoglobin, Hct and red blood cell parameters are considered to be sex dependent but others (MCV; MCH; MCHC, RDW) are generally calculated for the general population (6).

Iron and iron binding capacity of subjects in the study group could not be determined because there was not any relevant physical sign or symptom of anaemia. In our check-up procedure, additional laboratory tests are ordered if any physical sign or symptom exists, or any disturbance was detected by individuals/subjects. Subjects with a past history of any disease, previous blood donations, extraordinary nutritional habits were enquired about and subjects who donated blood less than six months previously, experienced serious diseases or anaemia previously, consuming more than 20 cigarettes in a day, and who are under drug therapy for any reason, were excluded. Red cell distribution width of all subjects were in normal value, so iron deficiency anaemia with normal erythrocyte indices was not considered although iron and iron binding capacity levels were not studied. Subjects who had any disease or disturbance together with abnormal laboratory results were excluded from the study, but anyone who had no disturbance or symptom in physical examination but abnormal laboratory test results (full blood count, liver and renal function tests, electrolytes, urinalysis) were not excluded from the study group.
Our laboratory is included in a quality control program with daily, weekly and monthly calibrations for instrument imprecision, so accuracy of measurements can be considered reliable. Together with efforts spent in quality improvement, each laboratory can develop its own references if sufficient contributions can be made.

In conclusion, reference values of haematological parameters in middle-aged healthy men were evaluated. The contribution of this study could be in presenting reference values of Anatolian males that can be used in clinical settings or in analytical laboratories to calculate relevance of laboratory full blood count test results. Reference values obtained in this study may also be compared with other studies conducted in populations from different geographical and environmental conditions.

Figure 1: Percentiles of body mass index in 18-24, 25-34, 35-45 years old males

Figure 2: Percentiles of Hb for 18-24, 25-34, 35-45 years old males

Figure 3: Percentiles of body mass index in 18-24, 25-34, 35-45 years old males

Figure 4: Percentiles of body mass index in 18-24, 25-34, 35-45 years old males

Figure 5: Box plot diagram of full blood count parameters

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Table 1: Full blood count measurements of 18-45 years old males and comparison of subjects reference value with the Coulter

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Table 2:

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