Why are Thyroid disorders on the rise?

“Bu tchaennus thyroidun khatam ke’rmitch” (thyroid has devastated me) is something you often hear when ladies gossip here in Kashmir. It may be a blatant exacerbation but scores the point that thyroid disorders are pretty prevalent here.

WHAT IS THYROID?

   

The thyroid is a large butterfly-shaped gland located in the middle of the lower neck. It secretes thyroid hormones that regulate growth and development by controlling the rate of metabolism in the body. Like all endocrine glands, it is a ductless organ and puts its hormones directly into the bloodstream, around 85 mcg of T4 and 6.5 mcg of T3 daily.

The fact that it is ductless and has no connection with the throat means that thyroid dysfunction doesn’t directly affect the throat. But, of course, when you have overt hypothyroidism, the whole body, including the throat, is involved. So, if you have any symptoms related to the throat, the best thing to do is consult an ENT specialist and not go straightway for a thyroid function test (TFT).

WHAT ARE THYROID DISORDERS?

Thyroid disorders or diseases can be broadly structural or functional. Structurally, there can be an increase in the size or nodularity of the gland (goitre) with or without malignant transformation. Functionally, the gland may become overactive (hyperthyroidism) or underactive (hypothyroidism), producing too much or too little thyroid hormones, respectively.

Thyroid-stimulating hormone (TSH) secreted into the blood by the pituitary gland in the brain is an indirect indicator of thyroid function, with low TSH indicative of an overactive gland and high TSH level indicative of an underactive gland. However, there are exceptions to this rule, and one should avoid self-interpretation.

Instead of asking the lab guy who is qualified only to do and not interpret it, one should always consult a qualified endocrinologist because TFT or any hormone test is always to be interpreted in relation to the clinical setting.In most cases of TFT abnormalities, the level of thyroid hormones (T4 and T3) is normal as per the lab reference range, and only TSH is raised, that too mildly.

The latter condition is called subclinical hypothyroidism, the most common form of thyroid disease prevalent these days. Therefore, whenever someone says he has thyroid, invariably, it is a case of subclinical hypothyroidism.

HOW COMMON ARE THYROID DISORDERS?

Thyroid disorders are very common endocrine diseases worldwide and affect tens of millions of people. Over 4.2 crore Indians suffer from thyroid-related disorders, with approximately 1 in 10 Indian adults suffering from hypothyroidism.

The condition is twice as prevalent in women as in men, making some call it the ‘next diabetes’. While we don’t have any data on the changing incidence of thyroid disease (new cases per year) here in Kashmir, the prevalence of thyroid disease is undoubtedly on the rise.

CAUSE OF SURGE IN THYROID CASES

The most common cause of thyroid disease is thyroid autoimmunity, which is often triggered by stress. The prevalence of autoimmune diseases may generally be increasing, as is reflected by the increasing incidence of other autoimmune diseases. Current data suggest that COVID-19 may cause autoimmune thyroid disease or exacerbate the underlying thyroid disease in remission.

Other possible reasons that likely contribute to the rise in thyroid disease could be rising awareness of the disease, increasing survival of the population, eliminating iodine deficiency, endocrine-disrupting chemicals, and metabolic syndrome masquerading as thyroid disease.

Rising Awareness and Increased Testing: Thyroid disease is often asymptomatic or presents with subtle and non-specific symptoms, such as fatigue, weight gain, constipation etc. Therefore, they can only be identified following blood tests, and increased blood tests would be expected to result in an increased incidence of the thyroid.

Previously, TSH estimation in the Valley was only available in the Immunology lab of SKIMS Srinagar, which was one the best in quality control in the country. But now, with mushrooming of labs in every nook and corner, one is not sure about the analytical accuracy and precision of the lab in question. Also, TSH release is pulsatile with periodicities of 60 or 85-100 min.

In addition, there is a circadian periodicity characterized by a nocturnal surge that begins in the late afternoon and reaches a peak around midnight. TSH levels can also change transiently (and later return to normal) as part of the body’s adaptation to the underlying non-thyroidal illness that may be physical, mental or psycho-social. Therefore, many cases of thyroid disease could be misdiagnosed.

Elimination of Iodine Deficiency: Worldwide, iodine deficiency disorders (IDD) continue to be the commonest thyroid disease. In 1995, we showed a prevalence of goitre and IDD to be 45% among schoolchildren in an extensive survey reported in the American Journal of Clinical nutrition.

However, one and a half decades after implementing salt iodization, we noted a marked improvement in overall iodine nutrition in Kashmir Valley. The total goitre rate got reduced to under 4%. It is well known that when there is successful salt iodization, a regular increase in the population´s TSH is to be expected as the gland´s physiological response to an improved iodine availability.

Besides, with relaxation in salt iodization policy, iodine deficiency disorders in the community could be resurfacing – the latter are known to be associated with higher TSH levels.

Endocrine-Disrupting Chemicals (EDCs): Recent research has linked chemicals found in non-stick cookware, carpeting, and paints to an increase in thyroid disease.

Some identified chemicals include PFOA, PFOS) and PTFE (brand named as Teflon). Recent studies show that people with higher levels of these chemicals in the circulation have more thyroid disease.

Obesity/Metabolic syndrome and High-normal TSH: Recently it has been reported that a higher body mass index (BMI) is associated with high-normal TSH levels.

While the relationship between obesity and subclinical thyroid dysfunctions remains unclear, it seems that obesity and the consequent insulin resistance may play a pivotal role in the changes in thyroid homeostasis.

Therefore, TSH elevation may be a marker of obesity-insulin resistance rather than an indicator of thyroid disease.

CONCLUSION

There is a rising awareness of the disease in society, which means more patients with this condition are being diagnosed. Every case of TSH elevation need not be treated, and a period of careful observation on follow-up may suffice such cases.

There is no need to get frightened as the treatment of common thyroid disorders is simple and highly gratifying. Proper diagnosis and proper treatment improve the quality of life of the patients.

The author is MD, DM (Endo), FACP, FRCP (Edinburgh) and Professor, Department of Endocrinology,SKIMS Srinagar (J&K)

Disclaimer: The views and opinions expressed in this article are the personal opinions of the author.

The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK.

Leave a Reply

Your email address will not be published. Required fields are marked *

14 + thirteen =