Blood donors No./total (%) Hb (g/dl) mean ± SD Ferritin (ng/ml) mean ± SD EPO (mlU/mL) mean ± SD Group I Male 50/73 (68.5) 15.8 ± 1.0 129.5 ± 72.1 7.9 ± 3.9 Female 23/73 (31.5) 13.6 ± 0.9 52.5 ± 34.7 8.7 ± 4.5 Total 73/147 (49.7) 15.1 ± 1.4 105.3 ± 72.1 8.2 ± 4.1 Group II Male 10/15 (66.7) 16.0 ± 1.1 129.1 ± 95.2 8.0 ± 5.0 Female 5/15 (33.3) 13.3 ± 0.4 44.3 ± 39.2 6.4 ± 1.5 Total 15/147 (10.2) 15.1 ± 1.6 100.9 ± 89.3 7.4 ± 4.1 Group III Male 20/23 (87) 15.3 ± 1.3 82.2 ± 54.5 6.9 ± 2.5 Female 3/23 (13) 13.1 ± 0.3 11.4 ± 1.6 15.0 ± 13.8 Total 23/147 (15.6) 15.0 ± 1.4 73.0 ± 56.2 7.9 ± 5.5 Group IV Male 15/18 (83.3) 15.3 ± 1.0 44.3 ± 23.5 9.2 ± 5.8 Female 3/18 (16.7) 14.3 ± 0.9 65.4 ± 42.0 6.5 ± 1.8 Total 18/147 (12.2) 15.2 ± 1.1 47.8 ± 27.0 8.7 ± 5.4 Group V Male 13/18 (72.2) 15.4 ± 1.3 73.3 ± 87.2 8.3 ± 4.6 Female 5/18 (27.3) 13.7 ± 0.5 25.0 ± 18.1 7.8 ± 4.8 Total 18/147 (12.2) 14.9 ± 1.4 59.8 ± 77.1 8.1 ± 4.6  p-value 0.133 0.001* 0.001*

Hb: Haemoglobin, EPO: erythropoietin. *Statistically significant difference of serum ferritin (p=0.001) and erythropoietin levels (p=0.001) with the frequency of donation per year. Donors were divided into five groups according to the frequency of donation during a one year period preceding this study (April 2011- April 2012): Group I (No.=73) includes the first-time donors. Group II (n=15): includes those who had donated once in the previous year and were donating for the second time with an interval of more than 3 months (Rang: 3 - 6). Group III (n=23) includes those who had donated twice in the previous year and were donating for the third time. Group IV (n=18) involves those who had donated three time in the previous year. Group V (n=18) involves those who had donated four times in the previous year and were donating for the fifth time. Groups II, III, IV and V donors were considered regular donors (n=74)

Table 2: Relationship of haemoglobin, serum erythropoietin and ferritin levels with studied donor groups.