The effect of repeated blood donations on the iron status of male Saudi blood donors

Abstract

Background.

Regular blood donation can lead to iron deficiency. Screening donors’ serum ferritin levels at the time of first donation and subsequently once every year is a very rational way to pick up iron deficiency in a voluntary blood donor population. The aim of this study was to determine the effect of blood donation and the prevalence of erythropoiesis with iron deficiency (sideropenia) in Saudi male blood donors.

Materials and methods.

The study was prospectively conducted, between December 2008 and March 2009, on 182 male native Saudi blood donors at King Fahd Central Hospital in Jazan region, Saudi Arabia. Each donor gave 450±50 mL of whole blood. Following the donation, samples were removed into 2.5 mL EDTA tubes for measurement of mean cell volume (MCV) and mean corpuscular haemoglobin (MCH) and into 7.5 mL plain tubes for estimation of iron and serum ferritin concentrations. The blood donors were divided into five groups, according to the number of donations they had given in the preceding 3 years. The blood donors in group I were first-time donors, with no previous history of blood donation. Group II donors had donated once in the last 3 years. Subjects in groups III, IV and V had donated more than once in the preceding 3 years and were considered regular donors.

Results.

The mean serum iron was significantly higher among subjects with no previous history of blood donation (group I) than among regular donors who had donated twice or more. The difference in serum ferritin concentration was statistically significant (p<0.05) when comparing regular donors in group III (72.4 μg/L), group IV (67.4 μg/L) and group V (26.2 μg/L) with first-time blood donors (131.4 μg/L). In contrast, the difference in the concentration of serum ferritin between subjects in group II (98.9 μg/L), who had donated once in the last 3 years, and in first-time blood donors (131.4 μg/L) was not statistically significant (p<0.131). None of the group I donors suffered from iron deficiency, whereas 2.8% of the donors who had donated between two to five times had iron deficiency. The prevalence of erythropoiesis with iron deficiency in regular blood donors was 4.3%.

Conclusion.

The results of this study show that an increase in the number of donations results in an increase in the frequency of depleted iron stores and subsequently in erythropoiesis with iron deficiency, although the level of haemoglobin remained acceptable for blood donation. This result may indicate the need to review the guidelines on acceptance of donors.

Introduction

Iron deficiency is the most common nutritional deficiency in both developing and developed countries. Regular blood donation may be an important cause of iron loss. Each 1.0 mL of blood contains approximately 0.5 mg of iron. A unit of donated blood therefore contains approximately 250 mg of iron and a single donation of one unit of blood can lead to the loss of 236 mg iron in men and 213 mg in women. Iron stores are approximately 30% lower in female donors than in male donors who give one unit of blood yearly. Iron deficiency has been observed in long-term blood donors^1–3.

In the majority of blood banks, haemoglobin has generally been used as a screening test for the suitability to give blood. However, the use of this parameter has been reported to have poor sensitivity in the detection of early stages of iron deficiency^2,4. Indeed, an accurate diagnosis of a state of iron deficiency requires several laboratory tests. Measurements of serum iron and serum ferritin concentrations and red cell indices such as mean cell volume (MCV) and mean corpuscular haemoglobin (MCH) can be used with a high degree of accuracy and precision^5–7.

To our knowledge, no systematic study has been conducted in Saudi Arabia to assess iron stores in blood donors. Since it would not be appropriate to use the results of studies in other countries for Saudi blood donors, the main objective of this research was to conduct the first study to evaluate the effect of frequent blood donation on iron stores of regular male Saudi blood donors.

In this study, iron stores were considered depleted when serum ferritin values were between 12–14 μg/L, reduced when the values were between 15–30 μg/L and normal when values were between 31–300 μg/L. Erythropoiesis with iron deficiency (sideropenia) was considered present when the serum ferritin concentration was below 12 μg/L⁸.

Materials and methods

One hundred and eighty-two male native Saudi blood donors were prospectively included in this study between December 2008 and March 2009 at King Fahd central hospital in Jazan region, Saudi Arabia. All selected donors were healthy according to their clinical histories and physical examinations and fulfilled the suitability criteria for donation (haemoglobin >12.5 g/dL).

A simple short questionnaire was given to each donor to obtain his consent to take part in the study. After donation of 450±50 mL of whole blood, samples were removed into 2.5 mL EDTA tubes for assays of haemoglobin, MCV and MCH and into 7.5 mL plain tubes for measurement of iron and serum ferritin concentrations.

Data on the number of donations in the preceding 3 years were recorded from the blood bank computer database. Red cell indices (MCV and MCH) and haemoglobin were measured by a Beckman Coulter counter (Coulter Corporation, USA). Iron and serum ferritin were measured using Dimension RXL Max (Dade Behring, USA) and Cobs e601 (Roche-Hitachi, Germany) automated analysers.

Data were analysed, using SPSS computer software (SPSS Inc., Chicago, IL, USA). A t-test for independent samples was used. p values less than 0.05 were considered statistically significant.

Results

A total of 182 Saudi blood donors were included in this study. All donors had haemoglobin concentrations greater than 12.5 g/dL. The population under study was divided into five groups according to the number of donations the subjects had made in the preceding 3 years. The blood donors in group I (n=26; 14.3%) were first-time donors with no previous history of blood donation. Donors in group II (n=64; 35.2%) had given blood once in the preceding 3 years. Group III donors (n=71; 39.0%) had donated from 2–5 times in the preceding 3 years, group IV donors (n=16; 8.8%) had donated from 6–9 times in the preceding 3 years and group V donors (n=5; 2.7%) had donated from 10–12 times in the preceding 3 years. Groups III, IV and V donors were considered regular donors. The age range of all donors was between 19 and 50 years with a mean age of 29.2 (standard deviation, SD=6.5) years (Table I).

Table I.

Distribution of donors according to frequency of donation and age.

Groups	Number of donations	Number of donors	Age (years) Mean (range)	Percentage (%)
Group I	0	26	26 (19–35)	14.3
Group II	1	64	29 (20–48)	35.2
Group III	2–5	71	29 (19–42)	39.0
Group IV	6–9	16	33 (26–50)	8.8
Group V	10–12	5	32 (23–37)	2.7
Total	-	182	-	100

Serum iron concentration was evaluated in all five groups of blood donors. In group I, the mean serum iron concentration was 20.4 μmol/L (SD=3.0), while in group II it was 18.7 μmol/L (SD=7.6). In groups III, IV and V the mean serum iron concentration was 17.0 μmol/L (SD=6.7), 17.8 μmol/L (SD=5.4) and 14.8 μmol/L (SD=6.8), respectively (Table II, Figure 1). The mean serum iron concentration was significantly higher in group I donors, who had no previous history of blood donation, than in donors in groups III, IV and V who had given blood twice or more in the preceding 3 years (Table III).

Table II.

Mean values of iron and ferritin concentrations, MCH and MCV in donors grouped according to frequency of donation.

Groups	Number of donations	Iron (μmol/L)	MCH (pg/cell)	MCV (fL)	Ferritin (μg/L)
Group I	0	20.4	27.4	73.2	131.4
Group II	1	18.7	27.3	73.6	98.9
Group III	2–5	17	26.7	73.2	72.4
Group IV	6–9	17.8	26.1	73	67.4
Group V	10–12	14.8	26.5	73.7	26.2

Figure 1.

Iron concentration of blood donors according to frequency of donation.

Table III.

Statistical analysis (p values) of the differences between means of iron, ferritin, MCV and MCH when comparing donors grouped according to the frequency of previous donations.

Group comparison (n. of donations)	MCV	MCH	Iron	Ferritin
Group I : group II (0 : 1)	0.844	0.958	0.263	0.131
Group I : group III (0 : 2–5)	0.964	0.295	0.014*	0.000*
Group I : group IV (0 : 6–9)	0.923	0.160	0.048*	0.009*
Group I : Group V (0 : 10–12)	0.879	0.527	0.005*	0.016*

^*Statistically significant (p<0.05)

The differences in MCH and MCV comparing all groups with each other were not statistically significant (Table III).

The mean ferritin concentration in first-time blood donors, 131.4 μg/L (SD=90), was higher than that in donors in groups II, III, IV and V: 98.9 μg/L (SD=92.5), 72.4 μg/L (SD=49.8), 67.4 μg/L (SD=31.7), and 26.2 μg/L (SD=21.8), respectively (Table II, Figure 2). Looking at the concentration of serum ferritin in first-time and regular donors (groups III, IV and V), it was seen that ferritin levels decreased with increasing number of donations (Table II). The serum ferritin concentrations were statistically significantly different when comparing regular blood donors (groups III, IV and V) with first-time donors (group I) as shown in Table III.

Figure 2.

Ferritin concentration of blood donors according to frequency of donation.

The percentage of blood donors with reduced iron stores (ferritin concentrations 15–30 μg/L) rose as the number of donations increased. Iron stores were reduced in 3.8% (1/26) first-time donors (group I), whereas 20% of the group V donors, who had donated between 10 and 12 times, had reduced iron stores (Table IV).

Table IV.

Distribution of population under study according to iron status and frequency of donation.

Groups	Number of donation	Number of donors	Ferritin
			15–30 μg/L (reduced iron)	12–14 μg/L (depleted iron)	<12 μg/L Erythropoiesis with iron deficiency (sideropenia)
Group I	0	26	3.8% (n=1)	0% (n=0)	0% (n=0)
Group II	1	64	12.5 (n=8)	1.6% (n=1)	0% (n=0)
Group III	2–5	71	16.9 (n=12)	2.8% (n=2)	2.8% (n=2)
Group IV	6–9	16	12.5% (n=2)	0% (n=0)	0% (n=0)
Group V	10–12	5	20% (n=1)	0% (n=0)	40% (n=2)

None of the group I donors or donor who had only given blood once before (group II) suffered from iron deficiency, while 2 out of 71 (2.8%) of the donors who had donated two to five times (group III) had ferritin concentrations below 12 μg/L, i.e. they had erythropoiesis with iron deficiency (sideropenia). Overall, the prevalence of erythropoiesis with iron deficiency in regular blood donors (groups III, IV and V) was 4.3% (4 out of 92).

Discussion

One of the most frequent observations in long-term blood donors is chronic iron deficiency^1–3. Iron deficiency is the state in which the content of iron in the body is less than normal. Iron depletion is the earliest stage of iron deficiency, and signifies that iron stores are decreased or absent, but the serum iron concentration and blood haemoglobin levels are normal. Iron deficiency without anaemia is a somewhat more advanced stage of iron deficiency, characterised by decreased or absent iron storage, usually a low serum iron concentration and low blood haemoglobin concentration, but without anaemia⁹.

Blood banks have the responsibility to protect blood donors, which includes preventing anaemia among them. In this population-based study the concentrations of serum ferritin (and thus stored iron) among Saudi male blood donors were measured and the prevalence of those with a serum ferritin concentration below 12 μg/L, i.e. erythropoiesis with iron deficiency, was determined. A donation frequency of more than four or five units per year could not be compensated by iron absorption and resulted in iron deficiency^10–11.

Early detection of iron deficiency among blood donors would allow appropriate readjustment of donation intervals and would guide the use of iron supplementation. It has recently been recommended that short-term iron supplementation combined with adjustments of haemoglobin acceptance levels may reduce the rate of donor deferral for low haemoglobin¹². Several studies have used serum ferritin concentration as an indicator of iron stores^1,7.

The mean results of the haematological parameters (MCV, MCH) in the current study were generally lower than reference values even among those donors who had not given blood before (group I). This finding enforces the results of two previous studies which indicated that several haematological parameters in Saudi nationals are significantly lower than those in western populations. The reasons for these differences are not clear and a more comprehensive study examining the potential causes is required¹³.

The results of this study show that the ferritin concentrations decreased significantly with an increase in the number of donations. These results are similar to those reported by other authors^14–17. In the present study, about 12.5% of those who had donated once (group II) had ferritin levels between 15 and 30 μg/L, i.e. reduced iron stores (Table IV). This percentage increased to 16.3% (15 out of 92) in regular blood donors (groups III, IV and V) as shown in Table IV. The percentage of iron deficiency (depletion) in regular blood donors (groups III, IV and V) was 2.17% (2 out of 92) and 4.3% (4 out of 92) of the regular donors (groups III, IV and V) had erythropoiesis with iron deficiency (sideropenia), as shown in Table IV.

The results of this study also show that an increase in the number of donations results in an increased prevalence of depleted iron stores and, consequently, erythropoiesis with iron deficiency.

The haematological parameters MCV and MCH have been reported to be useful in the identification of iron deficiency⁷. In this study, no statistically significant changes were observed in either MCV or MCH with increasing number of donations.

The current guidelines in most countries require the determination of haemoglobin and haematocrit levels before blood donation. However, with regards to meeting safety requirements for donors, haemoglobin and haematocrit are unsuitable for use as a screening tool for the diagnosis of iron depletion.

In conclusion, this study shows that there is high prevalence of reduced iron stores, especially among regular blood donors, despite these donors being eligible to give blood according to the current guidelines (haemoglobin >12.5 g/dL). The use of parameters that reflect iron status more accurately (serum iron concentration and ferritin level) would ensure a safer blood donation process for donors.