THYROID FUNCTION STATUS IN PATIENT WITH IRON DEFICIENCY ANAEMIA IN A TERTIARY CARE HOSPITAL OF LALITPUR, NEPAL

Introduction: Studies have found that iron deficiency anaemia(IDA) impairs thyroid hormone metabolism. The prevalence of thyroid dysfunction in adults in the general population ranges from 1 to 10 percent, and is even higher in selected groups. Thus in this study we would like to see thyroid function status in people with IDA. Methods: It was Laboratory based cross sectional study conducted in the Department of Biochemistry of a tertiary care hospital of KIST Medical College and Teaching Hospital, lalitpu, Nepal. Secondary data of 162 patients available in laboratory database of 3 years’ duration from August 2018 to August 2021 were taken. All Patients diagnosed with IDA whose thyroid profile was also done were included in the study. Data were entered in Microsoft Excel. Statistical analysis was performed using version 29 of the Statistical Package for Social Sciences (SPSS Inc, Chicago IL, USA). Results: Among 162 IDA patients, 86.4% (n=140) were females and 13.62% (n=22) were males. Age ranged widely from 19 to 88 years and median age was 38 years. Out of 162 patients most of the patients 68.5% were euthyroid, 8.7% had euthyroid hypothyroxinemia, 7.4% had primary hypothyroidism,3.7% had subclinical hypothyroidism, 3.1% had secondary hypothyroidism, 1.2% had primary hyperthyroidism, 1.2% had T3 toxicosis, 0.6% had euthyroid hyperthyroxinemia. Based on multiple independent KW test, relationship between category of thyroid disorders and iron profile as well as thyroid disorder and Hb level were found not to be statistically significant. No category of thyroid dysfunction was associated with value of haemoglobin level or severity of anaemia. Irrespective of category of thyroid profile including euthyroid, hypothyroid and hyperthyroid, no category is particularly associated with IDA. Conclusions: In patients with IDA, there is no significant association between Hb level or severity of iron deficiency irrespective of patient being euthyroid, hypothyroid or hyperthyroid.


INTRODUCTION
Anaemia is defined as haemoglobin (Hb) levels <12.0 g/dl in women and <13.0 g/dl in men. 1 Anaemia is one of the major public health problems with its global prevalence of 22.8% and dietary iron deficiency is the most common cause of anaemia. 2 Thyroid hormones (THs):Thyroxine (T4) and 3,53'-triiodothyronine (T3) are key determinants of cellular metabolism.They are important for optimal functioning of almost all tissues with major effects on metabolic rate and oxygen consumption. 3 Human study done by Grymula et.al. demonstrated for the first time that thyroid hormone receptors are present in human cord blood , peripheral blood and bone marrow CD34+ enriched cells. They have suggested that thyroid hormone, T3, is one of the factors that may play a role in regulation of cell population growth and the process of apoptosis of human haematopoietic cells. 4 Subsequent study by the their team indicate that both hypo-and hyperthyroidism significantly affect the proliferative potential of haematopoietic Progenitor Cells. 5 Normal thyroid status is dependent on the presence of many trace elements like iron, iodine, selenium, and zinc as these are required for both the synthesis and metabolism of thyroid hormones. Deficiencies of these elements can impair thyroid functions. Iron deficiency impairs thyroid hormone synthesis by reducing activity of hemedependent thyroid peroxidase enzyme which catalyses initial step of thyroid hormone synthesis. 6 The thyroid function status can be categorized based on serum levels of free T3 (fT3), free T4 (fT4), and Thyroid stimulating hormone (TSH) into: 7,8,9 • Euthyroid: normal fT3, fT4 and TSH normal TSH Studies have found that iron deficiency anaemia(IDA) impairs thyroid hormone metabolism. 10 8 with depleted iron stores (nonanemic The prevalence of thyroid dysfunction in adults in the general population ranges from 1 to 10 percent, and is even higher in selected groups. 11 Thus in this study we would like to see thyroid function status in people with IDA.

MATERIALS AND METHODS
It was Laboratory based cross sectional study conducted in the Department of Biochemistry of a tertiary care hospital of KIST Medical College and Teaching Hospital, Lalitpur, Nepal. Secondary data of 162 patients available in laboratory database of 3 years' duration from August 2018 to August 2021 were taken. Diagnosis of IDA was done by laboratory-confirmed evidence of anaemia indicated by low Hb, as well as evidence of low iron stores evidenced by low serum iron, a low serum ferritin, a low transferrin saturation, and a high total iron-binding capacity (TIBC). 12 All Patients diagnosed with IDA whose thyroid profile was also done were included in the study. Data with missing relevant demographic characters like age and sex and patients from department of Obstetrics and Gynaecology and paediatrics were excluded. Before commencing the study ethical approval was obtained from Institutional Review Committee of KIST Medical College and Teaching Hospital, Imadol, Lalitpur (Ref.No: 2077/78/73).
Data were entered in Microsoft Excel. Statistical analysis was performed using version 29 of the Statistical Package for Social Sciences (SPSS Inc, Chicago IL, USA). Normality of data distribution was assessed by Kolmogorov-Smirnov test. Based on the observations of the test, most of the variables in the study were found to be highly skewed so median and median absolute deviation were calculated and further Independent-Samples Kruskal-Wallis tests were carried out to examine the relationship between category of thyroid disorder and haemoglobin including iron profile.

RESULTS
Among 162 IDA patients, 86.4% (n=140) were females and 13.62% (n=22) were males. Age ranged widely from 19 to 88 years and median age was 38 years Level of significance for Kolmogorov-Smirnov (KS) value was observed to be less than 0.05 for all the variables and most of the variables in the study were found to be highly skewed which suggests that the observed data has non-normal distribution, so median and median absolute deviation were calculated as depicted in table 1.  Figure 1. Independent-Samples Kruskal-Wallis tests were carried out to examine the relationship between category of thyroid disorder and Haemoglobin including iron profile. Based on multiple independent KW test, relationship between category of thyroid disorders and iron profile as well as thyroid disorder and Hb level were found not to be statistically significant. No category of thyroid dysfunction was associated with value of haemoglobin level or severity of anaemia. Irrespective of category of thyroid profile including euthyroid, hypothyroid and hyperthyroid. No category is particularly associated with IDA as depicted in table 2.  16 Thus from our study we can say that there is no statistically significant prevalence of thyroid dysfunction in patient with IDA.

CONCLUSION
In patients with IDA, there is no significant association between Hb level or severity of Iron deficiency irrespective of patient being euthyroid, hypothyroid or hyperthyroid.