Thyroid hormone plays an important role in different metabolism in the body. Hematopoietic system is the primary one among the affected systems and anemia is the most important one. Anemia in hypothyroidism is usually mild-to-moderate degree, but severe anemia is rarely reported. A 6-year-old child presented with poor appetite and examination showed severe anemia, short stature, X-ray of bilateral knee joint - epiphyseal dysgenesis in the lower end of femur and thyroid function showed decreased T3 and T4 with increased TSH level. Other tests like hemoglobin electrophoresis, G6PD, DCT, ANA, iron, vitamin B12 and folic acid level were normal. So, the diagnosis of acquired hypothyroidism with severe anemia was made. Though anemia is a known entity in hypothyroidism but severe anemia with hemoglobin 3 gm% is rare.
Thyroid hormone is secreted from the thyroid gland. Frequency of hypothyroidism differs from one society to another. Two to five percent of prevalence has been reported throughout the world. However, the prevalence of subclinical hypothyroidism is approximately 4-8.5% and can reach up to 20% in women aged 60 years or older
Thyroid hormone plays an important role in different metabolism in the body. There is a metabolic deceleration in hypothyroidism. All organ systems are affected and clinical feature depends on the age of occurrence and the degree of hypothyroidism (deficiency or insufficiency). Hematopoietic system is the primary one among the affected systems and anemia is the most important one. Anemia is reported in 20-60% of the patients with hypothyroidism. Anemia in hypothyroidism is usually mild-to-moderate degree, but severe anemia is rarely reported. Anemia can be normochromic normocytic, hypochromic microcytic and macrocytic. Anemia severity is associated with the degree of hypothyroidism. Severe anemia, in a case of hypothyroidism is very rarely described in the available literature. We are presenting a child with severe anemia due to hypothyroidism.
A 6-year-old boy presented to our OPD with chief complaints of poor appetite. On examination, child had severe anemia but no clubbing or jaundice. No past history of blood transfusion. No family history of mental retardation or similar illness or multiple blood transfusions. Development was normal except mild delay in motor development. His height was less than third percentile (World Health Organization [WHO] chart) but weight was normal. Abdominal examination revealed no hepatosplenomegaly. Cardiovascular examination showed ejection systolic murmur in pulmonary area. On standing, child had varus deformity in both lower limbs. Lab investigation showed hemoglobin (Hb) 3 gm% with normal total leukocyte and platelet count. Peripheral smear showing microcytic hypochromic picture. X-ray of bilateral knee joint showing epiphyseal dysgenesis.
So from the above findings etiological work up for anemia was done. Iron, vitamin B12 and folic acid level were normal. Vitamin D level and renal function test were normal. Hb electrophoresis was normal. Thyroid function test was done, which showed low triiodothyronine (T3) and thyroxine (T4) level with increased thyroid-stimulating hormone (TSH) level (T3- , T4- , TSH-). Thyroid ultrasound showed atrophic thyroid gland. Thyroids scan showing very minimal uptake of radioisotope in the thyroid tissue. Antinuclear antibody (ANA) and direct Coombs test were negative. From the above clinical picture and laboratory investigation diagnosis of acquired hypothyroidism with severe anemia was made. Child was transfused with 2 units (total 20 mL/kg) of packed red cell. Post-transfusion Hb was 6 gm%. Child was started with thyroid hormone (50 µg/day). Though iron study was normal child was also started with iron and folic acid to meet the excess demand of increased erythropoiesis. After 2-month of follow-up child’s Hb was 12 gm% and thyroid function test was normal. Appetite and physical activity had improved.
According to WHO, prevalence of anemia is 24.8% throughout the world and it is seen more frequently in underdeveloped countries.Most common cause of anemia is nutritional. Thyroid hormone (T3 and T4) also has a significant influence on erythropoiesis. Most commonly encountered anemia in hypothyroidism is normochromic normocytic anemia and cause of anemia is bone marrow depression due to thyroid hormone deficiency as well as lack of erythropoietin production arising from the reduction in need of oxygen due to decreased activity. Erythrocyte life cycle in hypothyroidism is normal, and there is hypoproliferative erythropoiesis. Thyroid hormones also increase 2,3-diphosphoglycerate (2,3-DPG) levels assisting in the transmission of oxygen into the tissues.
Autoimmune thyroiditis can be seen with other autoimmune disorders. Pernicious anemia can accompany hypothyroidism as a constituent of polyglandular autoimmune syndrome. Failure of vitamin B12 absorption occurs in pernicious anemia due to intrinsic factor (IF) deficiency and gastric achlorhydria. This is one of the reasons of macrocytic anemia in hypothyroidism. Macrocytosis is found in 55% of the hypothyroid patients. Folic acid is another vitamin with impaired intestinal absorption, and causing macrocytic anemia in hypothyroidism.
Iron deficiency anemia is related with menorrhagia occurring as a result of various hormonal imbalances and also malabsorption, which is seen in hypothyroidism.
In the study, by R Carnel and colleagues, thyroid disorder and hypothyroidism were determined respectively in 24.1% and 11.7% of the patients with pernicious anemia.
Insufficient intake, absorption change arising from deceleration in intestinal motility, intestinal wall edema and bacterial infiltration are blamed among other reasons causing vitamin B12 deficiency in hypothyroidism.
Folic acid deficiency occurs as a result of intestinal malabsorption. Again hypothyroidism ruins folate mechanism by decreasing hepatic level of dihydrofolate reductase such as methylenetetrahydrofolate reductase.
In hypothyroidism, malabsorption and iron deficiency anemia occurs as a result of various hormonal instability. In a study carried out by Cinemre H and colleagues, they showed that the efficacy and absorption of oral iron treatment in women with subclinical hypothyroidism improved after levothyroxine replacement. This demonstrates that hypothyroidism should be assessed in patients with anemia.
Anemia is not always due to nutritional deficiency and we should always try to find the exact etiology whenever possible especially when there is certain other clinical finding apart from anemia. Hypothyroidism is an endocrine disorder and is frequently seen in the society. Anemia in hypothyroid patient occurs as a result of various causes. Determination of etiological reasons of anemia and arrangement of the treatment is important.
About the Authors
Suprabha Shukla, Dillip Kumar Das, Jnanindra Nath Behera
Senior Resident, SCB Medical College, Cuttack, Odisha
Assistant Professor, Hi-Tech Medical College, Bhubaneswar, Odisha
Professor, Dept. of Pediatrics, SCB Medical College, Cuttack, Odisha
Address for correspondence
Dr Suprabha Shukla
C/o: Bijay Mohan Biswal
House No. 14, Malhasahi, Mangalabag, Cuttack, Odisha