The Association of Iron Deficiency and Fatigue in Non-Anemic Females of Childbearing Age: An Nhanes Analysis

Introduction:

Iron deficiency (ID) is the most common nutritional deficiency in the world and remains relatively common in at-risk groups in the United States. The development of (ID) is dependent upon the individual's iron stores which is a  balance between iron absorption and loss. Commonly associated with (ID) is iron deficiency anemia (IDA) which has a well known association with fatigue. Fatigue is a common complaint in general, with a prevalence in population-based surveys in Great Britain and the United States of 6.0 and 7.5 % respectively. However it is not uncommon to have (ID) without subsequent anemia in females childbearing age group. Our study aims to evaluate the prevalence of ID in non anemic females of childbearing age and its association with fatigue.

Methods:

Data was obtained from continuous NHANES database,  a nationally representative health survey conducted from 2005-2010. The data including age, race, complete blood count (CBC), ferritin and fatigue was obtianed from laboratory and questionnaire datasets, respectively.  Subjects were further divided based on ferritin levels into two groups, Group A; ferritin ≤20 ng/mL  and Group B; ferritin >20 ng/mL. The question regarding fatigue - “ feeling tired or having little energy for past two weeks” was obtained from PHQ-9 scale.  Univariate analysis was done comparing Group A and Group B using chi-square test and t-test for categorical and numerical variables, respectively.  The effect of iron deficiency on fatigue was obtained using logistic regression to calculate odds ratio (OR) after adjusting for age and race.

Results:

Of 3230 female subjects( age 18yrs -49yrs), there were 809 with ID with no anemia. The weighted prevalence  of iron deficiency in non-anemic women of childbearing age was 22.5% (95% CI 20.76-24.22). The weighted  prevalence of fatigue in Group A and Group B was 61.8% (95% CI 56.4-67.2) and 59.7 % (95%CI 57-62.4) respectively (p=0.45)(table 1). In multivariate analysis, after adjusting for age and race, the odds ratio (OR) for fatigue with iron deficiency was 1.1 ( 95% CI 0.8-1.4).

Conclusion:

The prevalence of ID in non anemic females of childbearing age in the United States  was 22.5 % .The percentage of subjects who reported fatigue was significantly high in both iron deficient and non-iron deficient subjects in this age group. There was no statistical difference in self-reported fatigue in both iron deficient and non-iron deficient women of childbearing age. Further studies are needed  to validate our findings.

 

Table1: Comparision of GpA and GpB
Variables	Ferritin≤ 20 ng/mL (GpA)	Ferritin > 20 ng/mL
Fatigue - Yes	512	1452
Fatigue - No	297	986
Total	809	2421