BENGALURU: Doctors in Karnataka are seeing cases of Covid patients developing inflammation in the thyroid gland.The thyroid gland regulates the body's growth and metabolism and inflammation can cause it to produce too little or too much of these hormones.
Although little research has been done on the relationship between thyroid and Covid-19, a recent study in China on 50 patients suggests the thyroid stimulating hormone (TSH) was lower than the normal range in 56% of Covid-19 patients.
The study found that the more severe the form of Covid-19, the lower the levels were of TSH and triiodothyronine (T3 thyroid hormone). But, thyroid hormones bounced back to normal after recovery.
TSH levels drop in about 5-10% of Covid patients in Karnataka, said Dr Anoop Amarnath, head of the scientific board at Manipal Hospital and member of the state's Critical Care Support Team. Low TSH levels combined with high levels T3 and T4 thyroid hormones indicate hyperthyroidism.
Dr Amarnath said the drop in TSH levels is seen mostly in patients with a pre-existing thyroid disorders.
"If TSH drops further, patients can go into coma, but we have not seen such a scenario. It is advisable that T3, T4 and TSH levels are checked. There have also been cases of Sick Euthyroid Syndrome, which are characterised by low T3 and normal TSH, reflecting the fact that normal hormonal feedback is dysregulated in critical illness," he said.
Some Covid patients at Sakra World Hospital developed inflammation of the thyroid gland, said Dr Subrata Das, senior consultant of internal medicine and diabetology at the hospital.
"Those who already had thyroid disorders were more prone to complications, although we still don't know if the inflammation of the thyroid is due to Covid-19. The patients have increased tremors, joint pain, increased heart rate, fatigue, and increased feelings of hunger. Medication is given to reduce inflammation," said Dr Das.
Doctors at Aster CMI Hospital have noticed that men tend to have milder thyroid involvement during and after Covid infection. More research needs to be done to ascertain why Covid-19 affects the thyroid gland, said Dr Mahesh DM, endocrinology consultant at Aster CMI Hospital.
“(But) research has shown that angiotensin-converting enzyme 2 (ACE2) demonstrated to be a key host-cell entry receptor for SARS-CoV-2 is expressed in the thyroid and the lungs, where it causes Covid-19's notorious pulmonary effects," he said.
Rates of thyrotoxicosis - a condition associated with excess circulating thyroid hormones - due to a form of subacute thyroiditis - are significantly higher among critically ill Covid-19 patients, which suggests an atypical form of thyroiditis related to SARS-CoV-2, he said.
While there is a link between thyroid and Covid-19, there is no reason to panic.
"Currently, there is no indication that patients with autoimmune thyroid disease are at greater risk of getting Covid-19 or of being more severely affected should they be infected with Covid-19," Dr Mahesh said.