THIRUVANANTHAPURAM: In view of the high prevalence of goitre, in 2008 American Thyroid Association first celebrated ‘World Thyroid Day’ on May 25 and later on thyroid day was observed worldwide. Goitre (enlargement of thyroid gland) caused due to iodine deficiency is very high in many areas of the world like the high mountain regions of Andes, Alps, Great lakes of USA, several pockets of Africa and the sub Himalayan regions of India, Pakistan, Nepal and Bangladesh. These regions are known as goitre belts.
In a survey conducted recently in 352 districts of India, goitre was found to be endemic in 263 districts. The main cause was attributed to iodine deficiency in the diet as well as in the drinking water. Studies conducted in the hilly regions of Idukki and Kottayam district by the author in 1980’s, found an incidence of goitre up to 20 per cent in some regions and about 10 per cent in school children.
The nation wide prevalence of iodine deficiency prompted the Indian Government to introduce compulsory iodine supplementation (Potassium iodide 20-30/million parts) of common salt as a part of the VIIth plan 20 point programme introduced by the late Rajiv Gandhi. It is estimated that there are 50 million people with goitre, 2.2 million cretins and 6.6 million children born with neurological defects in India due to iodine deficiency.
The daily requirement of iodine is about 150-200 micrograms/day and the iodine is mainly utilised by the thyroid gland for the synthesis of thyroid hormones, which is necessary for the growth of every organ in the body especially the brain. The butterfly shaped thyroid gland situated in front of the neck weighing 15-20 gm, produces about 100 microgram of thyroid hormones per day. These hormones, identified first in 1915 are Thyroxine (T4) and Tri-iodothyronine (T3) and the main component of thyroid hormones is iodine (67% by weight).
Barring diabetes mellitus, thyroid disease is the commonest endocrine disease in India. Hypothyroidism (underactive thyroid) is 10 times more common than hyperthyroidism (overactive thyroid) and 10 times more common in females. From 1870 onwards scientists doubted that ‘something in thyroid, was essential to life and in 1891, an English Physician George Murray prepared extracts from the thyroid gland of sheep and fed to a patient with Myxedema (extreme hypothyroidism) which cured the patient.
The only person till now who was awarded a Nobel Prize for thyroid research was ‘Theodor Kocher’ (Bern, Switzerland) in 1909 and his incision for thyroid surgery is still used universally - (‘Kochers incision’). Besides complications during pregnancy like abortions, intrauterine growth retardation and premature labour, hypothyroidism can also produce congenital cretinism (dwarfism, obesity, hoarse voice, protuberant abdomen), low IQ and cognitive defects in the child. Delayed detection of hypothyroidism in children can result in low IQ and mental deficiency since the brain develops during the first three months of foetus up to 2 years of life
Many famous people like former American President George Bush senior, Barbara Bush, the five time Olympic medalist Carl Lewis, the fastest woman in the 1992 summer Olympics (Spain) Gale Devers, Argentina President Christine Fernandez and actor Catherine Bell are thyroid patients. In fact, the defeat of Napolean Bonaparte (1769 - 1820) in the Franco Russian War (1881) was alleged to be due to the wrong and foolish decisions taken by him because of his ‘hypothyroidism’. Even King David who always had subnormal body temperature (King of Israel from 1010-970 BCE) was said to have hypothyroidism. In the old Testament (Kings I, Chapter I) it is stated “Though they spread covers over him, he could not keep warm; so his servants said to Him, let a young virgin be sought to attend the King. She can be beside him so that our lord the King may keep warm.”
The author has come across several members in the same family affected with hypothyroidism, and also hypothyroidism extending to 3-4 generations. This is called ‘familial hypothyroidism’. Till 10 years ago, the exact cause of this hypothyroidism was not known and was attributed to geographical iodine deficiency or genetic defects. With the availability of laboratory tests to detect thyroid autoantibodies, it is found that 70 per cent of thyroid diseases are due to ‘antibody mediated thyroiditis’. These antibodies act against the thyroid cells suppressing thyroid hormone production resulting in hypothyroidism. A study undertaken in SUT Hospital, Pattom, Trivandrum showed a thyroid antibody prevalence in 29 per cent of pregnant women and 7 per cent of these patients were hypothyroid. 80 per cent of pregnant women with hypothyroidism had positive thyroid autoantibodies. Antibodies were also found to be positive in 89 per cent of adult asymptomatic females and 72 per cent of adult asymptomatic males (18-35 years of age). The most disturbing finding was that thyroid antibodies present in the pregnant mother would be transferred to the baby in 75 per cent of cases which could explain ‘familial hypothyroidism’.
Hypothyroid patients who are on thyroid medications should never stop the medicine during pregnancy, in fact it will be beneficial if they increase the dose of thyroxin by 25mcg during pregnancy even before consulting the doctor. Similarly all children/ adolescents/ adults with positive family history of hypothyroidism should be subjected to thyroid autoantibodies and thyroid function tests. Screening of pregnant women for thyroid autoantibodies is a must and should be introduced in all hospitals for early detection of thyroid related complications as well as predicting neonatal hypothyroidism. Babies with positive antibodies but normal thyroid function should be screened periodically to detect the early development of subclinical hypothyroidism easily.
- Prof K P Poulose (Principal Consultant in Medicine & Thyroidologist, SUT Hospital, Pattom)