Comparison of Serum Ferritin Levels in ThreeTrimesters of Pregnancy and Their Correlation with

Increasing Gravidity

Naghmi Asif, Khalid Hassan, Shaheen Mahmud, Hassan Abbass Zaheer,Lubna Naseem, Tahira Zafar and Rabia Shams

Department of Pathology, Pakistan Institute of Medical Sciences, Islamabad.

Background: During pregnancy there is an immense stress on iron metabolism and itfrequently induces iron deficiency, which is characterized by a reduced ferritin level. Thedemand of iron is variable during the three trimesters and the practices of iron supplementationare also not uniform. Therefore serum ferritin levels can be variable during different trimestersof pregnancy.Objective: To compare maternal serum ferritin levels in three trimesters of pregnancy andtheir correlation with increasing gravidity.Materials & Methods: This descriptive, comparative study was conducted at the departmentof pathology, PIMS, Islamabad from January to March 2006. A total of 150 females (50 fromeach trimester) were randomly selected during their routine antenatal checkup. Theirhematological parameters were measured on a fully automated hematology analyzer. Serumferritin levels were done using Elisa technique. Serum ferritin levels in three trimesters werestatistically compared using SPSS version 12.0. Results: Serum ferritin was found to be lower in 2nd as compared to 1st trimester (p < 0.001). It was significantly higher in 3rd as compared to second trimester (p < .001). Serum ferritinlevels did not show a significant correlation with increasing gravidity. Hemoglobin alsodecreased with increasing gestational age. Results of other parameters were variable.Conclusion: Serum ferritin levels were significantly lower in 2nd trimester with increase again in3rd trimester. Increasing Gravidity had no significant effect on serum ferritin levels.Key words: Serum ferritin levels; pregnancy.

Introduction

Anemia during pregnancy is considered as an established risk factor for both mother and fetus. It is well known that hemoglobin concentration falls during pregnancy principally as a result of hemodilution. If iron is not supplemented, mostof women are exhausted of their iron stores and therefore develop iron deficiency anemia. The diagnostic workup for iron deficiency includes red cell indices, serum iron, serum total ironbinding capacity, serum transferrin saturation, serum transferrin receptors level and serumferritin level. Microcytosis is a sensitive index of iron deficiency but its value is limited byphysiological increase in MCV that often occurs during pregnancy. Serum iron transferrin isfrequently abnormal in pregnancy. Low sensitivity of transferrin saturation and day to day and even hour to hour fluctuation of serum iron levels renders it less efficient than serum ferritin level for diagnosing iron deficiency which is theonly condition associated with decreased serum ferritin concentration1. Several studies have proven that serum ferritin is the single best non invasive test and is a veryuseful and reliable index of iron stores especially during pregnancy with low levels indicatingiron deficiency 2-4. It is the best indicator of discrimination between iron replete and irondeficient subjects and except for bone marrow biopsy is the best measure of body iron stores.There is only one limitation with serum ferritin, as it is an acute phase reactant and is not asensitive indicator of iron stores in those suffering from an infection, inflammation or cancer.Serum ferritin concentration shows a marked decrease after 12 weeks of gestation withrelatively constant values after 32 weeks. This decline is more in women who start pregnancywith inadequate stores and in those who had three or more pregnancies. In recent years, theserum transferrin receptor (TfR) level has been introduced as promising new tool for thediagnosis of iron depletion5. Routine daily iron supplementation during pregnancy has been found to improve the iron status

of both mother and baby, and also the outcome of pregnancy 6,7 have shown that serumferritin values continue to be remain low during pregnancy irrespective of supplementationsince the demand for iron outstrips the supply and supplementation helps in preventing thedepletion of iron stores. Thus, iron replacement in deficient mothers, detected by low serumferritin concentration, seems most appropriate1.The objective of this study was to determine the concentration of serum ferritin in differenttrimesters of pregnancy, and to correlate it with increasing gravidity.

Materials and Methods

This prospective, comparative cross-sectional study was performed at department of Pathology,Pakistan Institute of Medical Sciences from Jan 2006 to March 2006.A total of 150 pregnant ladies (50 from each trimester) presenting at MCH Centre lab wereselected randomly during their antenatal visits. Patients with history of diabetes, hypertension,hepatitis and any other acute or chronic illness were excluded from the study. Their relevanthistory regarding age, parity, gestational age, drug history and general health status was taken.

Table 1: Distribution of Cases According toTrimesters and Gravidity (Number of Cases)

1stTrimester(50)

2ndTrimester(50)

3rdTrimester(50)

Group 1(50 Cases)

20

13

17

Group 2(76 Cases)

26

27

23

Group 3(24 Cases)

4

10

10

A 2-3 ml of EDTA-blood sample was collected for hematological parameters which were measured on a fully automated hematology analyzer (Sysmex KX-21) and two ml of blood was collected in gel tubes. Serum was separatedand subjected to measurement of serum ferritin level by Elisa method (on a fully automatedEliza plate reader; Best 2000).

Table 2: Relevant Clinical Parameters

1st Trimester

2ndTrimester

3rd Trimester

Age17 - 3624.84 + 3.71

18 - 3625.18 + 3.72

19 - 4527.14 + 5.49

Gravidity1 - 82.42 + 1.63

1 - 82.40 + 1.60

1 - 83.06 + 1.86

Full TermPregnancies

0.00 - 4.001.06 + 1.18

0.00 6.001.26 + 1.50

0.00 - 6.001.64 + 1.67

No ofAbortions

0.00 - 4.000.34 + 0.515

0.00 1.000.18 + 0.38

0.00 - 4.000.44 + 0.63

Table 1 shows the breakup of patients according to trimesters (fifty from each trimester) andgravidity [Group 1 (primigravida) included 50 cases. Group 2 (gravida 2, 3 and 4) had 76 casesand group 3 (gravida 5 and above) had 24 cases.

Table 3: Hematological Parameters in Three Trimesters

1st Trimester2nd

Trimester3rd

Trimester

HB*7.60 - 14.20

(11.15 + 1.24)

6.10 - 12.70(10.20 +

1.25)

7.60 - 13.50(10.65 +

1.30)

RBCCount

3.09 - 5.67(4.23 + 0.51)

2.28 - 4.71(3.98 + 0.45)

3.29 - 4.89(3.95 + 0.40)

HCT25.80 - 40.50(34.04 + 3.41)

24.00 - 39.20(32.79 +

3.45)

22.40 - 38.70(32.78 +

3.62)

MCH19.30 - 33.50(27.15 + 3.36)

15.80 - 33.80(27.06 +

3.59)

19.60 - 33.5(27.68 +

3.67)

MCHC29.50 - 36.50(33.0 + 1.91)

23.70 - 36.10(32.46 +

2.40)

28.60 - 35.60

(31.82 +1.76)

MCV64.70 - 95.20(81.48 + 7.56)

60.30 -102.10

(81.09 +8.82)

64.60 - 98.80(83.14 +

8.47)

* p Value: 1st & 2nd trimesters < 0.005

Results were analyzed using SPSS version 12. The numerical values of results of differenttrimesters and groups were compared by Studentst test and p values were calculated.

Results

Table 2 shows the age representation, gravidity, number of full term pregnancies and thenumber of abortion in patients presenting in three trimesters.

Table 3 details the results of different hematological parameters in three trimesters. Asignificant decrease in hemoglobin concentration in second as compared to the first trimester (p< 0.005) was noted. Red cell count, hematocrit and absolute values (MCV, MCH and MCHC)however did not show statistically significant difference between the three trimesters (p >0.05).

Table 4: Hematological Parameters According to Gravidity

Group 1 Group 2 Group 3

Hb *7.60 - 12.70(10.73 +1.44)

6.10 - 14.20(10.66 + 1.24)

7.60 - 13.00(10.42 +1.16)

RBCCount

2.28 - 5.07(3.97 + 0.52)

3 - 5.67(4.06 + 0.40)

3.4 - 4.70( 4.02 + 0.32)

HCT22.40 - 39.8(32.59 +4.03)

24.0 - 40.5(32.98 + 3.37)

24.0 - 38.1(32.06 + 3.53)

MCV60.30 - 102(82.05 +3.88)

62 - 97(82.31 + 8.29)

64.70 - 98.5(80.54 + 8.30)

MCH19.40 - 33.8(26.98 +3.54)

15.80 - 36.1(26.77 + 2.08)

14.3 - 33.5(26.05 + 3.72)

MCHC29.4 - 36.3(32.7+ 1.78)

25.40 - 36.1(32.45 + 2.08)

23.70 - 36.5(31.84 + 2.67)

*p Value: Gp 1 & 2 < 0.05

Table 4 compares the same values according to gravidity and it also shows a statisticallysignificant decrease in hemoglobin level in group two as compared to group 1 (p < 0.05).Results of other parameters are comparable in three groups (p >0.05). Table 5 compares serum ferritin levels according to gestational age and gravidity. We found asignificant decrease in serum ferritin level in second and third trimesters as compared to first trimester (p < 0.001). Serum Ferritin levelshowever did not show any significant difference with increasing gravidity.

Table 5: Serum Ferritin (ng/ml) According toTrimester and Gravidity

AccordingtoTrimester

*1st Trimester

2nd Trimester

3rd Trimester

3.92 - 97.48 3.21 - 57.00 2.80 - 96.69

(26.62 +26.58)

(11.35 +9.25)

(20.42 +23.57)

AccordingtoGravidity

Group 1 Group 2 Group 3

3.92-97.48(21.20 +22.04)

2.80-93.83(16.55 +18.47)

4.10-68.9(14.73 +15.18)

* p value: (1st & 2nd 12ng/ml12-20ng/ml20-200ng/ml

25 (50%)05 (10%)20 (40%)

33 (66%)11 (22%)06 (12%)

23 (46%)13 (26%)14 (28%)

According toGravidity

Group 1 Group 2 Group 3

>12ng/ml12-20ng/ml20-200ng/ml

24(48%)08(16%)18(36%)

43(56.5%)19 (25%)14(18.5%)

14(58.5%)06(25%)04(16.5%)

Results of serum ferritin according to gravidity showed that 56.5% and 58.5% of women,belonging to group 2 and group 3 respectively, had ferritin levels less than 12ng/ml; only 16and 18% of females belonging to groups 2 and 3, respectively, showed ferritin levels between12 - 200ng/ml.

Discussion

Anemia is one of the most frequent complications related to pregnancy. All women during thechildbearing age are prone to develop iron deficiency but pregnant females are especially atrisk. Increased iron requirements during pregnancy are due to fetal growth and expansion ofred cells mass8. In Pakistan, 75-80% women suffer from iron deficiency anemia duringpregnancy9, probably due to poor nutrition, frequent and closely spaced pregnancies; in ruralsettings worm infestations may play an important additional role10. Detection of latent iron deficiency during pregnancy is important for both maternal and fetalwell-being but is generally difficult to detect. Routine parameters are only useful in the detectionof overt iron deficiency but not the sub clinical iron deficiency11. Measurements of serum iron,TIBC and percent transferrin saturation to assess iron deficiency during pregnancy are of

relatively limited value. Moreover, hemoglobin estimation and PCV estimation remain unreliableduring pregnancy due to physiological alterations in plasma volume and red cell number. Serum ferritin is therefore considered as a better parameter to detect latent iron deficiencyespecially before the change of red cell morphology and red cell indices. A high degree ofcorrelation has been shown between serum ferritin concentration and bone marrow iron stores. In thestage of latent iron deficiency (absence of storage iron), as assessed by marrow iron content, serumferritin concentration is decreased, but the transferrin saturation, serum iron, and hemoglobinlevels may remain unchanged12. During pregnancy, low serum ferritin concentrations in thepresence of normal hemoglobin indicate deficient iron stores13. Such females are prone todevelop overt iron deficiency anemia. In pregnancy, serum ferritin concentration is the maximum at 12-16 weeks of gestation, and then the levels start decreasing as the pregnancy advances14. Low serum ferritin levels duringsecond and third trimesters predict low hemoglobin levels in late pregnancy.In the present study, we compared serum ferritin concentration in three trimesters and found itscorrelation with other red cell indices so that in places where facilities for serum ferritinconcentration are not available they can be used as an alternative for detection of iron status ofmother.In our study serum ferritin was the lowest in second trimester when compared withfirst and third trimesters (p < 0.001). We also found a significant decrease in hemoglobinconcentration in second trimester as compared to first trimester (p < 0.05). Using ferritin level of12 ng per ml as the cut-off for iron deficiency, we observed that most of the women in 2ndtrimester (66%) were iron deficient; only 12% showed ferritin between 20-200 ng/ml in ourstudy. Our findings emphasize that in our setup, iron supplementation is probably sub-optimal.These findings are comparable with some previous studies which also showed adecrease in serum iron and ferritin in second and third trimesters2,4,15. They alsoshowed that maternal iron stores are depleted during 2nd trimester especially inwomen who are not receiving supplemental iron. Another study conducted at InhaUniversity Hospital, Korea revealed that on excluding all the subjects with evidence of anemia oriron deficiency from the pregnant study population, there were no significant differences ofserum ferritin levels between first and third trimesters of pregnancy in iron-replete group. Thesame study showed significantly decreased serum ferritin levels in the third trimester ascompared to the first trimester in iron depleted women. Low serum ferritin levels during secondand third trimesters predict low hemoglobin levels in late pregnancy 16.Ferritin is an acute phase reactant and is sometimes found elevated independent of the ironstatus during illness and inflammation17. Pregnancy is commonly associated with urinary tractinfections and some occult infections. In such individuals, high serum ferritin levels are likely tobe seen despite iron deficiency4, 18. Hence high serum ferritin levels do not necessarilyexclude the possibility of iron deficiency specially when there is suspicion of infection and moretowards the end of pregnancy. These are the only limitations in use of serum ferritin as anindicator of iron deficiency. Serum ferritin levels do not reflect the true iron status after deliveryas it is an acute phase reactant and is also affected by the amount of blood loss duringdelivery19.We found a significant decrease in hemoglobin in group two (gravida 2, 3 and 4) and groupthree (gravida five and above) as compared to group I (primigravida) with p value

results of this study also indicated that the fall in MCV, MCH and MCHC showed a linearcorrelation with serum ferritin level.

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