The overbearing physiological changes marring iron indices interpretation in response to iron therapy during pregnancy

 

 

Abstract              Background: Iron deficiency anemia (IDA) is most common cause of anemia in pregnancy. In order to prevent this iron supplementation is routinely practiced as a prophylactic measure in pregnant women all over. The biochemical parameters assessed in IDA comprise an iron profile evaluation which consists of estimation of serum ferritin, serum iron, total iron binding capacity(TIBC), serum transferrin levels and calculation of transferrin saturation. These biochemical parameters are subjected to variations due to maternal adaption phenomenon. Aim: In the current study we have chosen three iron indices, serum iron, serum TIBC and transferrin saturation percent to note their performance in diagnosing and monitoring the response to iron therapy in pregnant women. Methodology: The study population are thirty- six pregnant women in their early second trimester, who are diagnosed with mild iron deficiency anemia (Hemoglobin between 9 and 11 g %). Iron parameters, serum iron, serum TIBC and transferrin saturation levels were analyzed in these women. They are then given oral iron preparation in the form of Ferrous sulphate for a period of twelve weeks. After this the Hemoglobin level, serum iron, TIBC and transferrin saturation levels are re-analyzed in these women. Results: The hemoglobin levels increased (p= 0.002). as expected after oral iron intake. Serum iron levels improved from 58.19±39.07 to 64.78±34.96 μg/dl. Serum TIBC value before supplementation 234.22±134.49 increased to 437.33±94.95 after, which contradicts the expected pattern seen in response to therapy in general population. Similarly absurdity prevails in transferrin saturation index levels which dropped from 36.8 ± 31.8 to 16.3 ± 10.6. Conclusion: The iron status during pregnancy is highly influenced by the maternal changes. And a blind interpretation of the report can lead to erroneous diagnosis. The interpretation of values should be based on the trimester specific reference ranges during pregnancy.

Key words: Serum iron, Total iron binding capacity, Transferrin saturation, Pregnancy.

 

INTRODUCTION

Anemia is one of the commonly prevailing hematological disorder in women across the world. According to World Health Organization (WHO), globally, one third of the reproductive age group women population suffer from anemia and 40 % of the pregnant women are anemic.¹ The prevalence of anemia in pregnant women between age 15 and 49 years in India according to recent WHO data is 50.1 %.² Iron deficiency anemia is frequently encountered type of anemia in women of reproductive age and in children. Anemia is one of the leading causes of maternal deaths. India contributes to about 80% of the maternal deaths due to anaemia in South Asia.³ National Iron Plus Initiative for Anemia Control by Government of India is an initiative to bring down prevalence rate of anemia among the vulnerable children and women population of the country.⁴ As a result of such initiation, we have observed a considerable 38 % decline in Maternal mortality rate, a key health index, in the past two decades in our country.⁵ Iron deficiency anemia (IDA) is most common cause of anemia in pregnancy. A lot of physiological changes during pregnancy make women easily susceptible to IDA. These include expansion in maternal blood and plasma volume and a decrease in hematocrit, as well as an increase in the levels of some plasma proteins.⁶  Also the fetal requirements for iron are met despite maternal deficiency. Maternal iron deficiency has a number of adverse consequences, including preterm delivery and low-birth-weight infants.⁷ In view of this impending fall in iron status that occurs due to physiological changes in pregnancy as well increased demand by the growing fetus, iron supplementation is routinely practiced as a prophylactic measure in pregnant women all over.⁸ The routine laboratory investigations to diagnose and monitor IDA are Hemoglobin concentration, red blood cell indices and peripheral smear. The biochemical parameters assessed in IDA comprise an iron profile evaluation which consists of estimation of serum ferritin, serum iron, total iron binding capacity, serum transferrin levels and calculation of transferrin saturation. The reference range of hemoglobin is 11 grams per deciliter in the first and third trimester of the pregnancy and 10.5 grams per deciliter in the second trimester.⁹The microcytic hypochromic blood picture is classic for IDA. There is no ambiguity in interpreting the results of these hematological indices in diagnosing IDA. However, the same does not apply when it comes to analyzing an iron profile parameters during pregnancy. These biochemical parameters are to subjected to variations due to maternal adaption phenomenon. In the current study we have chosen three iron indices, serum iron, serum TIBC and transferrin saturation percent to note their performance in diagnosing and monitoring the response to iron therapy in pregnant women.

 

METHODOLOGY

The study was conducted for a period of one and half years starting from February 2008 to August 2009 on pregnant women in their second trimester (between 14-20 weeks of gestation) attending antenatal clinic at M.S. Ramaiah Medical Teaching Hospital, Bengaluru. The Ethical clearance was obtained from the Ethical Review Board of the Institution prior to commencement of the study. An informed consent was taken from the pregnant women who were inducted in this study.

Thirty six Pregnant women of more than 14 weeks of gestation with Hemoglobin concentration between 9 and 11 g % were included in this study. Pregnant women with other medical illness or any intercurrent infection were excluded from our study.

 Blood samples were collected from pregnant women between 14-20 weeks of gestation and following laboratory tests were done:

• Hemoglobin Concentration:
• Peripheral smear
• Serum iron-By automated direct iron assays using chromophore Ferene.
• Serum TIBC- By fully automated method using chromophore Ferene
• Transferrin saturation was calculated as Serum iron/serum TIBC x 100

All the thirty-six pregnant women with mild iron deficiency anemia (hemoglobin concentration between 9-11g/dl) were given oral iron supplementation in the form of ferrous sulphate tablets for a period of twelve weeks.

Re-estimation of the following laboratory tests after a period of twelve weeks of supplementation therapy was done,

• Hemoglobin Concentration
• Serum iron
• Serum TIBC.
• Transferrin saturation was calculated

Statistical analysis: The mean value and Standard deviation for all the biochemical parameters was calculated. The Mean ± SD between the cases and controls were compared using student ‘t’ test. All statistical analysis was done at 5% level of significance.

 

 

 

 

 

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