Iron Status in Non-anemic Pregnant Females during the Third Trimester Inam-ul-Haq et al

Ann. Pak. Inst. Med. Sci. 2008; 4(2): 88-91 88

Original Article

Iron Status in Non-anemic Pregnant Females during the Third Trimester Objective: To assess the iron status in non-anemic pregnant females during the third trimester Subjects and Methods: In this prospective cross-sectional study, non-anaemic pregnant females (n=100) during third trimester of pregnancy were randomly selected. EDTA-blood samples were obtained, and subjected to analysis for the following haematological parameters: hemoglobin (Hb), red blood cell count (RBC count), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC), using an automated hematology analyzer (Sysmex Kx-21). Estimation of serum ferritin was done by chemiluminescent technique and serum transferrin receptors (sTfRs) were estimated by immunoenzymometric assay. Results: The serum ferritin levels ranged from 1.0 22.80 ug/l with mean + SD of 19.96 22.37. The levels of serum transferrin receptors ranged from 0.60 26.70 mg/l with a mean + SD of 3.83 3.15. Forty seven percent females were found to have serum ferritin levels below the reference range whereas 18% had serum ferritin levels at lower limits of the normal. Conclusion: Sixty five percent of non-anemic females were found to have iron deficiency state on the basis of serum ferritin estimation. Amongst these subjects, sTfR levels were found increased as well. Key words: Pregnancy, Iron deficiency state; Serum transferrin receptors; ferritin

Inam-ul-Haq* Idrees Farooq Butt** Khalid Hassan*** Naghmi Asif*** Waqas Tariq **** Yasir Mateen ***** *Assistant Professor of Physiology Rawalpindi Medical College, Rawalpindi. **Associate Professor of Physiology Army Medical College, Rawalpindi ***Department of Pathology, Pakistan Institute of Medical Sciences, Islamabad ****Shifa International Hospital Islamabad. *****Final year MBBS student, Rawalpindi Medical College, Rawalpindi.

Address for Correspondence: Dr. Inam-ul-Haq Assistant Professor of Physiology Rawalpindi Medical College Rawalpindi. Email: drinam_rmc@hotmail.com

Introduction

Iron deficiency is the commonest cause of

anemia all over the world. Most of the people with iron deficiency reside in the developing countries and consume iron deficient foods.1

It has been reported that 56% of pregnant women in low income countries are affected in contrast to 18% in high income countries.2 During pregnancy, there is disproportionate increase in the plasma volume than the erythrocyte number which produces fall in hemoglobin concentration.3 Moreover, the iron requirement generally exceeds the amount provided in the diet. Intestinal iron absorption increases during pregnancy but becomes poor in cases of associated parasitic and infectious diseases like urinary tract infections, malaria, hookworm and roundworm infestations.4 It was observed that early marriages, malnutrition, repeated pregnancies, less consumption of iron rich foods like meat and worm infestations are strong contributory factors for iron deficiency during pregnancy in rural population.5

Iron deficiency during pregnancy is associated with a number of maternal and fetal problems including

the risks of preterm births, low birth weight babies, perinatal mortality and intrauterine growth retardation.6 Formation of fetal hemoglobin and myoglobin requires iron. Iron is obtained from maternal stores, which progressively leads to depletion of iron in the mother. Iron requirements of fetus are increased after 30th week of pregnancy.7 The consumption of iron-rich foods during pregnancy alongwith proper iron supplementation is essential for the well-being of both mother and fetus.

During the course of development of iron deficiency, an individual passes through two stages of subclinical iron deficiency (iron deficiency state) before entering into third stage of clinical (overt) iron deficiency anemia. During the first stage, depletion of iron stores occurs. Serum ferritin levels start decreasing during this stage. However, hemoglobin (Hb), red cell indices along with serum transferrin receptors (sTfRs) are within the normal reference range.8 The second stage shows a further decrease in serum ferritin along with significant rise in sTfR levels. Hb and red cell indices are still within the normal limits.9 The third stage is the stage of clinical (overt) anemia showing fall in Hb, red cell indices and serum ferritin levels along with rise in sTfR levels.10

During pregnancy, physiological alterations in

Iron Status in Non-anemic Pregnant Females during the Third Trimester Inam-ul-Haq et al

Ann. Pak. Inst. Med. Sci. 2008; 4(2): 88-91 89

plasma volume and red cell mass diminish the reliability of Hb estimation or determination of hematocrit.11 Serum ferritin levels start decreasing as the pregnancy advances.12 Ferritin being an acute phase reactant may show falsely elevated levels during pregnancy. Hence detection of elevated levels of sTfRs in the presence of normal Hb helps to detect the iron deficiency state before anemia develops. STfR is neither influenced by acute phase reactions13 nor is it influenced by hemodilution in pregnancy14.

High levels of sTfR in pregnancy despite normal Hb concentration can detect mild iron deficiency of recent onset.14 Increase in the concentrations of sTfRs with the advancement of pregnancy reflects increased erythropoiesis during the course of pregnancy.15 Values above 2.75 mg/l indicate iron deficiency.10

Studies regarding the measurement of sTfR levels during pregnancy have been conducted in the developed countries but limited data is available regarding the estimation of sTfRs during pregnancy in the third world countries. This study was conducted with an aim to assess the iron status in non-anemic females during the third trimester of pregnancy. The study helped us to see the prevalence of iron deficiency state in females of rural areas around Rawalpindi.

Subjects and Methods

In this prospective, cross-sectional study, one

hundred females in the third trimester of pregnancy were selected from the ante-natal clinic of Holy Family Hospital, Rawalpindi.

All the ladies were non-anemic (Hb 11.0 gm/dl) having mean age 26.30 4.17 years and gestational age 33.94 3.02 weeks. They belonged to rural set-up and were taking hematinics as prescribed. Females coming for ante-natal checkup during the first and second trimesters of pregnancy were excluded from the study. Those giving history of bleeding or coming from urban set-up were not included.

After obtaining the informed consent and filling in the history proforma, about 7 ml of venous blood was obtained after clean venepuncture; about 2 ml was mixed with anticoagulant to estimate hematological parameters including hemoglobin, red cell count, packed cell volume, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration by fully automated hematology analyzer (Sysmex KX-21). Remaining 5ml of venous blood sample was centrifuged for 10 minutes after it got clotted. Serum was obtained and stored at 70 C. At the time of analysis, the serum samples were thawed at room temperature and centrifuged. Estimation of serum ferritin was done by chemiluminescent technique whereas levels of serum transferrin receptors were estimated by immunoenzymometric assay (IEMA).

The whole data was entered in SPSS version 12. Mean and standard deviation were calculated.

Results Table 1 shows various hematological

parameters in 100 pregnant females included in the study. Mean hemoglobin concentration shows that all were non-anemic. Mean red cell count is towards lower limit of the normal as mentioned in the table. Packed cell volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were also towards lower side of the normal as shown in table 1.

Table 1: Hematological Parameters (n=100)

Variable Mean SD Range

Hemoglobin (gm/dl) 11.72 0.602 11.10 14.30

RBC Count (x106/l) 4.37 0.505 3.50 6.36

PCV (%) 35.99 3.64 30.40 48.60 MCV (fl) 82.14 7.09 58.20 98.70 MCH (pg) 27.04 3.04 17.60 34.2 MCHC (gm/dl) 32.82 2.68 23.0 36.80

Table 2 shows the mean values of serum ferritin

and serum transferrin receptors. Mean serum ferritin is towards the lower limit of the normal whereas mean serum transferrin receptor levels are above the normal reference range (>2.75 mg/l).

Table 2: Serum Ferritin and Serum

Transferrin Receptor Levels (n=100) Variable Mean SD Range

Serum Ferritin (g/l)

19.96 22.37 1.0 22.80

Serum Transferrin Receptors (mg/l)

3.83 3.15 0.60 26.70

Table 3 shows values of serum ferritin and

serum transferrin receptors. Individuals (n=47) having their serum ferritin levels below 12 g/L were having serum transferrin receptors both above and below the reference range. Seventy two percent females were having sTfRs above the normal limits whereas 28% were having sTfR levels within normal limits. The second subgroup (n=18) had serum ferritin within the lower limits of the normal, i.e. 12-20g/l. This subgroup shows high value of sTfRs in 56%(n=10) females and

Iron Status in Non-anemic Pregnant Females during the Third Trimester Inam-ul-Haq et al

Ann. Pak. Inst. Med. Sci. 2008; 4(2): 88-91 90

normal levels in 44% (n=08) females. The third subgroup of pregnant females (n=35) was having serum ferritin above 20g/l. In this subgroup, 66% (n=23) ladies were having their sTfRs within the normal reference range whereas 34% (n=12) had sTfR values above the normal limits.

Table 3: Serum Ferritin versus Serum Transferrin Receptor Levels (n=100)

Serum Ferritin

(g/l) Serum Transferrin Receptors

Normal * Raised ** 20(n=35) 66 % (n=23) 34 % (n=12)

*< 2.75mg/l; **> 2.75mg/l

Discussion Detection of latent iron deficiency during

pregnancy is difficult to assess by using traditional parameters because of physiological alterations in the plasma volume and red cell number. Serum ferritin is therefore considered as a better parameter to detect latent iron deficiency. During pregnancy, low serum ferritin concentrations in the presence of normal hemoglobin indicate deficient iron stores.16 Such females are prone to develop overt iron deficiency anemia.

We assessed the iron status of pregnant females by estimating the serum levels of transferrin receptors and ferritin.

Non-anemic pregnant females coming for antenatal check-up during the third trimester of pregnancy were included in the study. The present study shows a fall in PCV but in one study, it was noticed that PCV declines throughout the first and second trimesters of pregnancy, then reaches the lowest point late in the second to early third trimester and then shows a rise again near the term.17 A wide variation of PCV throughout the pregnancy limits its usefulness as a parameter to assess the iron status.

It is a well-known fact that maternal iron stores become exhausted during second and third trimesters of pregnancy. A study conducted at Inha University Hospital, Korea revealed significantly decreased serum ferritin levels in the third trimester as compared to the first trimester of pregnancy.18

The present study shows mean value of serum ferritin as 19.96 g/l, which is towards the lower limit of the normal. sTfRs in our study were having a mean value of 3.83 mg/l. In another study, the mean sTfR value of 10.4 mg/l was observed in non-anemic

pregnant women during the third trimester.19 Another study mentions mean concentration of sTfRs as 8.76 mg/l in a group of non-anemic pregnant females.20 In the present study, it was also observed that 34% of females who were non-anemic having serum ferritin within the normal reference range had elevated levels of sTfRs. In an Indian study, 27% of non-anemic, iron-repleted females showed elevated sTfR concentrations.21 These non anemic pregnant women may sooner or later manifest iron deficiency anemia. In another study, it was observed that women having depleted iron stores both in early and late gestation, sTfRs showed an increase by 74% in late gestation whereas in the same study, the women who maintained their body iron stores throughout the pregnancy, sTfRs increased by 25%.15 The results of this study can closely be related with our study.

We observed raised levels of sTfRs in 72% of females having serum ferritin levels less than 12g/l whereas 34% females with sufficient iron stores were having raised sTfR levels as already mentioned. We also observed that females having borderline serum ferritin (12-20g/l) are prone to develop overt anemia as 56% of them were having elevated levels of sTfRs. Actually erythropoiesis is the main predictor of sTfRs in the pregnancy.22 Decreased erythropoiesis in the early gestation is responsible for decreased concentrations of sTfRs. This decreased erythropoiesis ensures increase in the plasma volume in the early gestation which will in-turn provide a stimulus for accelerated erythrocyte production in the late gestation.23

Conclusion In the present study, 65% of non-anemic

females were found to have iron deficiency state on the basis of serum ferritin estimation. Amongst these subjects, sTfRs were found variably increased as well.

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