Thyroid Function Tests and Iron studies
From Thyroid UK
Hypothyroidism or underactive thyroid can lead to poor iron absorption which is why it’s important to check your iron and ferritin levels.
What causes iron deficiency?
Iron deficiency is caused by a lack of iron in the body which in turn causes iron deficiency anaemia . It can be caused by dietary lack of iron, blood loss (i.e. stomach bleeding due to use of taking non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and aspirin and stomach ulcers; heavy periods, pregnancy and certain
health conditions.1
What are the symptoms of iron deficiency anaemia?
The symptoms of iron deficiency are:
- tiredness and lack of energy
- shortness of breath
- noticeable heartbeats (heart palpitations )
- pale skin
- headaches
- hearing ringing, buzzing or hissing noises inside your head (tinnitus)
- food tasting strange
- feeling itchy
- a sore tongue
- hair loss – you notice more hair coming out when brushing or washing it
- wanting to eat non-food items (for example, paper or ice) – called pica
- finding it hard to swallow (dysphagia )
- painful open sores (ulcers) in the corners of your mouth
- spoon-shaped nails
- restless legs syndrome
Also, iron and immunity are closely linked and therefore if you have low iron levels it may affect your immune system .
However, symptoms may depend on the severity of your iron deficiency.
Hypothyroidism can lead to reduced levels of hydrochloric acid in the stomach (as can anti-acid medications) leading in turn to poor iron absorption. Hypothyroidism can also result in lowered body temperature causing fewer red blood cells to be produced by the temperature-sensitive bone marrow.
Low iron/ferritin levels are a particular problem for those with hypothyroidism for several reasons.
Firstly, normal thyroid hormone metabolism depends on adequate supplies of iron, together with iodine, selenium and zinc. Secondly, symptoms of anaemia mimic those of hypothyroidism so causing
the patient to believe they are not taking enough thyroid medication or that the thyroid medication they are taking is not working.
For example, hair loss is a sign of hypothyroidism but it is also caused by low iron levels. Patients can easily believe that they have this as a remaining sign of hypothyroidism without realising they may have low levels of iron/ferritin. It is very important that all hypothyroid patients also get tested for iron/ferritin.
Thirdly, low iron levels may result in the thyroid peroxidase enzyme, which is iron-dependent, becoming less active so reducing the production of thyroid hormones. The thyroid metabolism may also be altered, the conversion of T4 (thyroxine ) into T3 (triiodothyronine ) slowed down, and the binding of T3 modified. The circulating levels
of TSH (thyroid-stimulating hormone) may also be increased.
In a PubMed Article :
Pol Arch Intern Med
. 2017 May 31;127(5):352-360. doi: 10.20452/pamw.3985. Epub 2017 Mar 28.
Anemia in thyroid diseases
Ewelina Szczepanek-Parulska, Aleksandra Hernik, Marek Ruchała
PMID: 28400547 DOI: 10.20452/pamw.3985
Abstract
Anemia is a frequent, although often underestimated, clinical condition accompanying thyroid diseases. Despite the fact that anemia and thyroid dysfunction often occur simultaneously, the causative relationship between the disorders remains ambiguous. Thyroid hormones stimulate the proliferation of erythrocyte precursors both directly and via erythropoietin production enhancement, while iron-deficient anemia negatively influences thyroid hormone status. Thus, different forms of anemia might develop in the course of thyroid dysfunction. Normocytic anemia is the most common, while macrocytic or microcytic anemia occurs less frequently. Anemia in hypothyroidism might result from bone marrow depression, decreased erythropoietin production, comorbid diseases, or concomitant iron, vitamin B12, or folate
deficiency. Altered iron metabolism and oxidative stress may contribute to anemia in hyperthyroidism. The risk of anemia in autoimmune thyroid disease (AITD) may be related to pernicious anemia and atrophic gastritis, celiac disease, autoimmune hemolytic syndrome, or rheumatic disorders. The coexistence of anemia and thyroid disease
constitutes an important clinical problem. Thus, the aim of this review was to provide a comprehensive summary of data on the prevalence, potential mechanisms, and therapy of anemia in the course of thyroid diseases from the clinical and pathogenetic perspectives.
Thyroid dysfunction and AITD should be considered in a differential diagnosis of treatment-resistant or refractory anemia, as well as in the case of increased red blood cell distribution width. Of note, the presence of AITD itself, independently from thyroid hormone status, might affect the hemoglobin level.