Background: Regular blood donation often cause iron deficiency. Changes of platelet count have been associated with iron deficiency anemia. We aimed to study the correlation between serum ferritin and platelet count in blood donors.
Methods: Full blood count was measured by Sysmex- KX-21N Haematology Analyser. Serum ferritin was examined using electrochemiluminescence technology of Cobas e 411 Analyzer.
Results: The only significant correlation between ferritin level and platelet count (r2 = 0.432, p = 0.012) demonstrated in blood donors whose serum ferritin was less than 60 ng/mL.
Conclusions: No significant association between ferritin and platelet count were found in healthy donors with ≥ or < 6 blood donations whereas the moderate positive association was found in blood donors with low ferritin concentration (< 60 ng/mL).
Ferritin, PLTs, Blood donors
Serum ferritin significantly declines with increasing numbers of whole blood donation. The prevalence of iron deficiency is increased with more frequent blood donation [1]. Measurement of hemoglobin level alone in blood donors may not be enough; estimation of serum ferritin may require to be examined to detect iron depletion before blood donation [2-4]. Approximately 250 mg of iron is lost with each whole blood donation. In addition, the limited iron absorption can cause iron deficiency in regular donors, particularly females [5,6]. Blood donors may have low ferritin levels, with or without anemia. Platelet counts may be affected by iron balance in blood donors [7]. Some patients with severe iron-deficiency anemia have decreased platelet count [8]. However, the association of iron deficiency with thrombocytopenia or thrombocytosis is variable among different population [9-12]. The relationship between ferritin level and platelet counts has poorly elucidated in blood donors [7]. The mechanism of thrombocytopenia development in severe IDA is not well defined, although the platelet count is improved after iron therapy, usually before increased the number of reticulocytes. Therefore, iron may be essential for platelet production [13]. The aim of the current study was to assess the possible relationship between serum ferritin and platelet count and to measure the ferritin levels in blood donors.
This cross-sectional study was performed on 94 Yemeni male donors aged 24-41 years who donated blood at Blood Bank, Central Health Laboratories, Sana'a from February 2021 to April 2021. The eligible donors were divided into two groups depending on the number of donations. The first group included donors who had previously donated whole blood less than six times. The second group consisted of donors who donated blood six times or more. Furthermore, in relation to ferritin results, donors were divided into two groups; donors with ferritin concentration less than 60 ng/ml and those with ferritin concentration more than 60 ng/ml. The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study protocol was approved by the Institutional Review Board of the Faculty of Medicine and Health Sciences, Sana'a University. Informed consent form was obtained from each eligible donor after explaining the purpose of the study.
Standard physical examinations were assessed by the blood bank staff. The donors' height and weight were measured and BMI, defined as weight (kg)/ height squared (m2), was calculated. Blood Pressure (BP) was taken from each donor by mercury sphygmomanometer. After blood donation of 450 ml whole blood, blood samples were taken into two tubes; an EDTA tube for full blood count and a plain tube for serum ferritin analysis. The serum from each sample was separated into two Eppendorf tubes and immediately stored at -20ºC for ferritin assay. Full blood count was measured by Sysmex- KX-21N Haematology Analyser (Sysmex Corporation, Japan). Serum ferritin was examined using electrochemiluminescence technology of Cobas e 411 Analyzer (Roche Diagnostic, Germany).
The results were analyzed by the Social Package of Social Sciences (SPSS) version 25 (SPSS Inc, Chicago, IL, USA). Ferritin and platelet count were log transformed because they were not normally distributed. Ferritin and platelet count means were subsequently transformed back and presented as geometric means and 95% confidence intervals. Independent-Samples T test was used to describe the mean differences between two groups of study. The association of ferritin with platelet count and both with other parameters were analyzed by simple linear regression in each group. The significant differences were indicated if p-value was < 0.05.
The demographic and hematologic parameters of the donors was shown in Table 1. There were no significant differences between first group (donation < 6 times) and second group (donation ≥ 6 times). Association of ferritin and Platelet Count (PLTs) with demographic and hematologic parameters among the first group was revealed in Table 2. BMI was significantly associated with PLTs (r2 = 0.441, p = 0.002). Furthermore, the association of PLTs and ferritin with demographic and hematologic parameters was evaluated in second group donors (Table 3). There were no significant association between PLTs and ferritin and other parameters.
Table 1: Demographic and hematologic parameters among first and second groups of donors. View Table 1
Table 2: Association of PLTs and Ferritin with demographic and hematologic parameters among first group donors. View Table 2
Table 3: Association of PLTs and Ferritin with demographic and hematologic parameters among second group donors. View Table 3
PLTs was significantly associated with ferritin level (r2 = 0.432, p = 0.012) in blood donors whose ferritin concentrations were less than 60 ng/mL (Table 4). Also, Diastolic Blood Pressure (DBP) was significantly associated with ferritin (r2 = 0.585, p = 0.002). In contrast, there was no significant association between PLTs and ferritin and other dependent variables in blood donors with ferritin levels more than 60 ng/mL (Table 5).
Table 4: Association of PLTs and Ferritin with demographic and hematologic parameters among donors who have ferritin level less than 60 ng/mL (n = 33). View Table 4
Table 5: Association of PLTs and Ferritin with demographic and hematologic parameters among donors who have ferritin level more than 60 ng/mL (n = 61). View Table 5
The exact mechanism of changes in platelet count with iron deficiency is not well understood. It may be explained by the alteration of the activity of iron dependent enzymes during thrombopoiesis [14]. Our study evaluated the relationship between ferritin level and platelet count in blood donors. We found no significant change in serum ferritin between blood donors who donated blood 6 times or more and those with blood donation less than 6 times. Also, in first group (donation < 6 times), BMI was significantly associated with platelet count. Previous studies revealed that elevated platelet count is associated with increased BMI due to chronic inflammation [15,16]. In the same line, Jeong, et al. found that hematological parameters such as PLTs, RBCs, WBCs, Hb and HCT increased with elevated BMI in children and adults [17].
Our study exhibited no significant relationship between ferritin level and platelet count in both blood donor groups, and this can be explained by no iron deficiency in the donors regarding to the results of serum ferritin. Our study donors donated whole blood less than 30 times. Relative "iron depletion" typically occurs when serum ferritin is 22-40 mg/dL [18, 19]. According to Prinsze, et al., ferritin level significantly decreased in blood donors with whole blood donation > 50 times as compared with donors with less than 10 donations [20]. Serum ferritin measurement is the most reliable initial test for iron deficiency anemia [21] and its levels in healthy blood donors are less altered by inflammation and provide a good indication of iron status [22]. However, a number of studies demonstrated no significant correlation between serum ferritin and platelet count in patients with IDA [10-12]. Similarly, an earlier report showed transferrin and transferrin saturation, not ferritin, are significant correlated with platelet counts among blood donors [7].
On the other hand, we found moderate positive correlation (r2 = 0.432, p = 0.012) between serum ferritin and platelet count in blood donors with ferritin concentration less than 60 ng/mL. We are in disagreement with the large retrospective study reporting no relationship between low ferritin level and platelet count in blood donors with or without IDA [23]. Moreover, ferritin level was positively associated with Diastolic Blood Pressure (DBP) in the donors with serum ferritin less than 60 ng/mL. Previous studies found positive correlation between serum ferritin, diastolic blood pressure and other components of metabolic syndrome [24-26]. Oshaug, et al. have reported that DBP was a predictor for ferritin level [27]. Limitations of our study is the small sample size and the inclusion of only eligible blood donors. Further studies in donors with IDA are warranted.
In conclusion, serum ferritin was positively associated with platelet count in blood donors with low ferritin levels (< 60 ng/mL). No such correlations were found in donors with ≥ or < 6 blood donations.
This study funding: none. The authors thank all the study donors.
(I) Conception and design: Boshra Al-Absi
(II) Administrative support: Mohammed Abdul Wahid Almorish
(III) Provision of study materials or patients: Boshra Al-Absi and Mohammed Abdul Wahid Almorish
(IV) Collection and assembly of data: Mohammed Abdul Wahid Almorish
(V) Data analysis and interpretation: Boshra Al-Absi
(VI) Manuscript writing: Boshra Al-Absi and Mohammed Abdul Wahid Almorish
(VII) Final approval of manuscript: Boshra Al-Absi and Mohammed Abdul Wahid Almorish
All authors have no conflicts of interest to declare.