Understanding Heterogenous Thyroid: Causes, Symptoms, and Treatment

In this blog, we will provide a brief insight into a heterogenous thyroid, a condition that presents variability at the level of the single thyroid follicle and/or the thyroid as a whole. We will look into the multiple causes of a heterogenous thyroid, including thyroid dysgenesis, thyroiditis, and genetic mutations. Furthermore, we will discuss the symptoms associated with this condition and the various treatment strategies available.
Greta Daniskova

Greta Daniskova

Greta is a BSc Biomedical Science student at the University of Westminster, London.

A blue image with text saying "Heterogenous Thyroid"

What is a Heterogenous Thyroid?

A heterogeneous thyroid has variability at the level of the single thyroid follicle and/or with the thyroid as a whole [1] This variability can manifest as different metabolic properties within the follicles including its iodinating capacity, peroxidase content, responsiveness to TSH, and growth tendency i.e. ‘hot’ and ‘cold’ follicles coexisting within multinodular goitres [1] a lump or nodule on the thyroid.

What are the Causes of a Heterogenous Thyroid?

Causes of a heterogenous thyroid are multiple and can be correlated to a plethora of pathological conditions and factors. One trigger is thyroid dysgenesis, which includes a series of developmental thyroid malformations broadly catalogued as a spectrum of embryonic thyroid anomalies, starting from a complete aplasia, a thyroid gland absent from the body (athyreosis), to a hypoplastic (underdeveloped) but normally located thyroid (thyroid hypoplasia), to an ectopically located thyroid gland (an ectopic thyroid) [2].

Another factor is thyroiditis: a suite of diseases in which thyroid tissue is destroyed and preformed thyroid hormones are released [3], which might happen because of infection, autoimmune disorders such as Hashimoto’s or Graves’ disease, drugs, or radiation therapy [4].

Thyroid heterotopia – normal thyroid tissue is found in an aberrant location, coexisting with a normal organ in a normal localisation – is another factor contributing to the heterogeneity of a thyroid [5].

Yet, the aetiology of a heterogenous thyroid can also be driven by genetic mutations. For example, heterozygous mutations in the thyroid stimulating hormone receptor (TSHR) and the dual oxidase 2 (DUOX2), result in a highly variable phenotypic presentation, including transient congenital hypothyroidism, subclinical hyperthyrotropinemia, and euthyroid in children [6].

Lastly, the presence of nodules on the thyroid, whether single (solitary thyroid nodule) or multiple (multinodular goiter), can cause the thyroid to enlarge and become heterogeneous [4].

What are the symptoms of a Heterogenous Thyroid?

A heterogenous thyroid, or thyroid nodule is common in irregular or uneven texture and is associated with different pathology such as hypothyroidism or hyperthyroidism. Thyroid disease can affect people in a wide range of ways, and some symptoms might not be apparent.

Fatigue then is also one of the most widespread symptoms among hypothyroidism patients, one which often comes with a sense of lethargy followed by a heightened intolerance to colds. [7, 8, 9, 10, 11, 12, 13, 14].

Weight gain is another symptom that is almost invariably reported in cases of hypothyroidism (it can also be accompanied by a swollen face and constipation) [7, 8, 9, 10, 11, 12, 13, 14].

Dry skin and dry, thinning hair are also common symptoms of hypothyroidism. Some individuals may also experience decreased sweating [7, 8, 9, 10, 11, 12, 13, 14].

More severe cases may eventually lead to unusual symptoms, such as dysarthria, slurred or excessively slow speech [13] or even cerebellar ataxia, a condition in which coordination and movement are impaired [8, 9].

In hyperthyroidism (the opposite of hypothyroidism), these symptoms can include nervousness or irritability; constant fatigue; muscle weakness and sometimes increased sensitivity to cold (but typically there will be an intolerance of heat); insomnia; tremors (sometimes just in the hands); shortness of breath or rapid and irregular heartbeat; frequent bowel movements or diarrhoea; and weight loss [15, 16].

Since these symptoms can be different for different people, and since many of them can have other underlying causes, if you experience any of them, talk with a healthcare provider about getting diagnosed and treated.

What are possible treatment strategies for a Heterogenous Thyroid?

A heterogenous thyroid, either in association with Graves’ disease/hyperthyroidism or for other reasons, can be managed by several treatment options.

Common regimens include antithyroid medications – drugs that lower thyroid hormone production [17, 18], including methimazole and propylthiouracil – yet less than 50% of patients in long-term follow-up remain in remission after antithyroid drugs [19, 20].

Radioiodine therapy is the second most commonly used treatment, especially in the USA. It is designed to destroy enough thyroid tissue to cure the hyperthyroidism. The dose depends on the pathology, and is usually around 400 MBq for a patient with Graves’ disease, rising to 800 MBq for a patient with a large multinodular goitre [21]. One radioiodine treatment cures more than 90% of patients, and the goitre shrinks afterwards [22].

Some patients go for surgery (subtotal or total thyroidectomy) especially those with large goitre or ophthalmopathy [19, 23].

There are also several treatment approaches for novel medications under investigation such as small molecules including thyroid hormone receptor antagonists such as synthetic compounds, drugs that interact with the TSH receptor and the TSH receptor antibodies, immunosuppressive treatment, glucocorticosteroids, rituximab and intrathyroid injection of dexamethasone [17].

Combination therapy (not standard therapy), meaning both T3 and T4, might be a consideration in some both as a preventive measure and a treatment [24, 25]. It is still being studied and might be beneficial for some patients.

No matter what, treatment is always highly personal after taking into account the individual patient’s condition, other health problems, and their own preference.

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Greta Daniskova

Greta Daniskova

Greta is a 2nd-year student currently pursuing her Bachelor's Degree in Biomedical Sciences at the University of Westminster in London. Currently, in her second year of undergraduate studies, she exhibits a keen interest in the dynamic field of healthcare. With a focus on understanding the intricacies of human biology and disease mechanisms, Greta is driven by a desire to contribute to advancements in medical research and patient care.