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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 14  |  Issue : 1  |  Page : 22-24

Study of anemia in primary hypothyroidism


1 Department of Medicine, Maulana Azad Medical College, New Delhi, India
2 Department of Medicine, Sri Aurobindo Medical College and PGI, Indore, Madhya Pradesh, India

Date of Web Publication20-Feb-2017

Correspondence Address:
Ram Prakash Patel
Department of Medicine, Maulana Azad Medical College, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0973-0354.200564

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  Abstract 

Context: Thyroid hormones directly or indirectly, through erythropoietin, stimulate growth of erythroid colonies. In the deficiency of thyroid hormones, anemia frequently develops and may be normocytic, hypochromic-microcytic, or macrocytic. Aims: In this study, we evaluated the types of anemia and its causes in patients with untreated primary hypothyroidism. Settings and Design: This is an observational study conducted at department of general medicine of a tertiary care center. The duration of study was 1 year, November 2015–October 2016. Subjects and Methods: Four hundred and seventy-two patients of overt hypothyroidism or subclinical hypothyroidism were evaluated for possible inclusion in this study. Out of these 112 participants were recruited for the study after fulfilling inclusion criteria. Statistical Analysis Used: Microsoft Excel® and SPSS® 20 for Windows® were used for data storage and analysis. The qualitative data were expressed in percentages, and quantitative data were expressed as mean ± standard deviation. Student's t-test and Chi-square test were used to determine statistical difference between variables. Results: In our study, anemia frequency was 18% in the subclinical hypothyroid patients and 11% in the overt hypothyroid group. In the subgroup analysis of the hypothyroid patients, anemia of chronic disease was most common anemia in patients with overt and subclinical hypothyroidism. Conclusions: Anemia is a common finding in overt hypothyroidism, but anemia is not listed among the consequences of untreated subclinical hypothyroidism. Type and cause of anemia is also different in overt and subclinical hypothyroid patients. Therefore, anemia in hypothyroidism needs to be properly evaluated because treatment varies with etiology of anemia.

Keywords: Anemia, chronic disease, hypothyroidism


How to cite this article:
Patel RP, Jain A. Study of anemia in primary hypothyroidism. Thyroid Res Pract 2017;14:22-4

How to cite this URL:
Patel RP, Jain A. Study of anemia in primary hypothyroidism. Thyroid Res Pract [serial online] 2017 [cited 2017 Mar 22];14:22-4. Available from: http://www.thetrp.net/text.asp?2017/14/1/22/200564


  Introduction Top


Hypothyroidism is a common endocrine disorder resulting from deficiency of thyroid hormone. In community surveys, the prevalence of overt hypothyroidism varies from 0.1% to 2%.[1],[2],[3],[4],[5] The prevalence of subclinical hypothyroidism is higher, ranging from 4% to 10% of adults, with possibly a higher frequency in older women.[6],[7],[8] The clinical manifestations of hypothyroidism are highly variable, depending on the age at onset and the duration and severity of thyroid hormone deficiency. Classic signs and symptoms (e.g., cold intolerance, puffiness, decreased sweating, and coarse skin) may not be present as commonly as once believed. Thyroid hormones directly or indirectly, through erythropoietin, stimulate growth of erythroid colonies. In the deficiency of thyroid hormones, anemia frequently develops and may be normocytic, hypochromic-microcytic, or macrocytic. Complete correction of anemia often requires restoration of thyroid function as well as specific therapy. Continued attention to hematologic status is essential in the management of patients with thyroid diseases. We need to evaluate the prevalence and types of anemia in primary hypothyroid patients because both have significant medical implications. In this study, we evaluated the types of anemia and its causes in patients with untreated primary hypothyroidism.


  Subjects and Methods Top


Study design

This is an observational study.

Study setup

This study is conducted at department of general medicine of a tertiary care center.

Study duration

The duration of study was 1 year, November 2015–October 2016.

Sampling

Purposive sampling technique is used for selection of desired samples according to inclusion criterion.

Sample size

Four hundred and seventy-two patients of overt hypothyroidism or subclinical hypothyroidism were evaluated for possible inclusion in this study. Out of these 112 participants were recruited for the study after fulfilling inclusion criteria.

Inclusion criteria

All adults with thyroid-stimulating hormone (TSH) >5.5 µIU/ml with anemia symptoms were included in this study.

Exclusion criteria

Patients with history of chronic cardiac/renal/liver diseases, chronic infections, hemolytic anemia, peptic ulcer, hemorrhoids, bone marrow suppression, or blood transfusion in last 3 months were excluded from the study.

Methods

Demographic characters such as age, sex, height, and weight of all participants were noted. Anemia has been defined as hemoglobin <13 g/dl in male or <12 g/dl in female. Sixty-six subclinical and 46 overt hypothyroidism patients as per standard definition were included in this study. The patients first underwent complete blood count for inclusion in the study. On the basis of red cell indices (mean corpuscular volume [MCV]), anemia has been classified as normocytic normochromic (MCV 80–96 fl), microcytic hypochromic (MCV <80 fl), and macrocytic (MCV >96 fl). Investigations like stool for occult blood, serum ferritin and high-performance liquid chromatography for hemoglobinopathies were done in cases of microcytic anemia. Serum assay of Vitamin B12 was performed for macrocytic anemia. In normocytic anemia, Coombs test and bone marrow examination were also done.

The diagnosis of hypothyroidism was based on clinical grounds as well as biochemically demonstration of suppressed levels of free thyroxine (58–161 nmol/L) and increased TSH (>5.5 µIU/L) using immune assay.

Ethical consideration

Before conduct of the present study, the protocol of the study was submitted to ethical and scientific committee of hospital. After getting due approval from these two committees, the present study was initiated. Furthermore, before conduct of study-related procedure/investigation, a voluntary written informed consent was taken from the patient/legally acceptable representative.

Statistical technique

Microsoft Excel ® and IBM, SPSS 20, SPSS Inc., 233 South Wacker Drive, 11th Floor, Chicago, IL 60606-6412, USA for Windows ® were used for data storage and analysis. The qualitative data were expressed in percentages, and quantitative data were expressed as mean ± standard deviation. Student's t-test and Chi-square test were used to determine statistical difference between variables.


  Results Top


In our study, anemia frequency was 18% in the subclinical hypothyroid patients and 11% in the overt hypothyroid group. There was no statistical difference in terms of anemia frequency between subclinical and overt hypothyroid groups (P = 0.06). Demographic measures and biochemical values of subclinical hypothyroidism and overt hypothyroidism participating in this study are shown in [Table 1]. While 40 females and 16 males had anemia in subclinical hypothyroid group, 12 females and 5 males had anemia in overt hypothyroid group. There was no statistical difference between gender distribution, hematocrit, hemoglobin, MCV, serum iron, serum ferritin, and Vitamin B12 level of the patients with anemia in both groups.
Table 1: Demographic measures and biochemical values

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In the subgroup analysis of the hypothyroid patients, anemia of chronic disease was most common anemia in patients with overt and subclinical hypothyroidism. The frequency of this type of anemia was determined to be 43% in patients with clinical hypothyroidism and 18% in patients with subclinical hypothyroidism. The difference between overt hypothyroid and control group was found to be statistically significant (P = 0.001).

Frequency of microcytic anemia in overt hypothyroid and subclinical hypothyroid patients was 34% and 54%, respectively (P = 0.006). Frequency of macrocytic anemia in overt hypothyroid and subclinical hypothyroid patients was 23% and 28%, respectively (P = 0.113). Normocytic anemia in overt hypothyroid and subclinical hypothyroid patients was 43% and 18%, respectively (P = 0.002).


  Discussion Top


Hypothyroidism can lead to a wide variety of anemic disorders. Numerous mechanisms are involved in the pathogenesis of these anemias which can be microcytic, macrocytic, and normocytic. Microcytic anemia is usually ascribed to malabsorption of iron and loss of iron by menorrhagia. Macrocytic anemia is caused by malabsorption of Vitamin B12, folic acid, and in inadequate nutrition. Normocytic anemia is characterized by reticulopenia, hypoplasia of erythroid lineage, decreased level of erythropoietin, and mainly regular erythrocyte survival. Anemia is a relatively frequent finding in overt hypothyroidism.[9] Anemia that normalizes in response to T4 replacement, even in the presence of normal serum iron, Vitamin B12, and folate is found in up to 25% of hypothyroid patients.[10] According to our findings, chronic disease anemia is the most common type of anemia in hypothyroid patients as similar to described in literature. Suspicion of hypothyroidism should be considered in every case of anemia with uncertain etiology. Most common type anemia in overt hypothyroidism is normocytic normochromic in our study. Iron deficiency is the second most cause of anemia followed by macrocytic anemia. While in subclinical hypothyroidism, most common type of anemia is microcytic hypochromic. These findings are similar to study by Erdogan et al.[11] Das et al. found the prevalence of anemia in subclinical and overt hypothyroid groups was 26.6% and 73.2%, respectively. They showed that the frequency of anemia in subclinical hypothyroidism is higher than general population.[12]


  Conclusions Top


Anemia is a common finding in overt hypothyroidism, but anemia is not listed among the consequences of untreated subclinical hypothyroidism. Our study showed that up to 18% of subclinical hypothyroidism patients are suffering from anemia. Type and cause of anemia is also different in overt and subclinical hypothyroid patients. Therefore, anemia in hypothyroidism needs to be properly evaluated because treatment varies with etiology of anemia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Tunbridge WM, Evered DC, Hall R, Appleton D, Brewis M, Clark F, et al. The spectrum of thyroid disease in a community: The Whickham survey. Clin Endocrinol (Oxf) 1977;7:481-93.  Back to cited text no. 1
    
2.
Vanderpump MP, Tunbridge WM, French JM, Appleton D, Bates D, Clark F, et al. The incidence of thyroid disorders in the community: A twenty-year follow-up of the Whickham survey. Clin Endocrinol (Oxf) 1995;43:55-68.  Back to cited text no. 2
    
3.
Canaris GJ, Manowitz NR, Mayor G, Ridgway EC. The Colorado thyroid disease prevalence study. Arch Intern Med 2000;160:526-34.  Back to cited text no. 3
    
4.
Aoki Y, Belin RM, Clickner R, Jeffries R, Phillips L, Mahaffey KR. Serum TSH and total T4 in the United States population and their association with participant characteristics: National Health and Nutrition Examination Survey (NHANES 1999-2002). Thyroid 2007;17:1211-23.  Back to cited text no. 4
    
5.
Unnikrishnan AG, Kalra S, Sahay RK, Bantwal G, John M, Tewari N. Prevalence of hypothyroidism in adults: An epidemiological study in eight cities of India. Indian J Endocrinol Metab 2013;17:647-52.  Back to cited text no. 5
    
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Hollowell JG, Staehling NW, Flanders WD, Hannon WH, Gunter EW, Spencer CA, et al. Serum TSH, T(4), and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). J Clin Endocrinol Metab 2002;87:489-99.  Back to cited text no. 6
    
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Walsh JP, Bremner AP, Feddema P, Leedman PJ, Brown SJ, O'Leary P. Thyrotropin and thyroid antibodies as predictors of hypothyroidism: A 13-year, longitudinal study of a community-based cohort using current immunoassay techniques. J Clin Endocrinol Metab 2010;95:1095-104.  Back to cited text no. 7
    
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Unnikrishnan AG, Menon UV. Thyroid disorders in India: An epidemiological perspective. Indian J Endocrinol Metab 2011;15 Suppl 2:S78-81.  Back to cited text no. 8
    
9.
Horton L, Coburn RJ, England JM, Himsworth RL. The haematology of hypothyroidism. Q J Med 1976;45:101-23.  Back to cited text no. 9
    
10.
Cinemre H, Bilir C, Gokosmanoglu F, Bahcebasi T. Hematologic effects of levothyroxine in iron-deficient subclinical hypothyroid patients: A randomized, double-blind, controlled study. J Clin Endocrinol Metab 2009;94:151-6.  Back to cited text no. 10
    
11.
Erdogan M, Kösenli A, Ganidagli S, Kulaksizoglu M. Characteristics of anemia in subclinical and overt hypothyroid patients. Endocr J 2012;59:213-20.  Back to cited text no. 11
    
12.
Das C, Sahana PK, Sengupta N, Giri D, Roy M, Mukhopadhyay P. Etiology of anemia in primary hypothyroid subjects in a tertiary care center in Eastern India. Indian J Endocrinol Metab 2012;16 Suppl 2:S361-3.  Back to cited text no. 12
    



 
 
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Abstract
Introduction
Subjects and Methods
Results
Discussion
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