The increasing burden of thyroid diseases in the State has been worrying doctors, especially gynaecologists, who point out that a significant percentage of women coming in to their clinics complaining of infertility, recurrent miscarriages, irregular menstrual cycles, unexplained weight loss or gain are being diagnosed with low functioning thyroid gland or hypothyroidism.
Thyroid is the small gland located at the throat but it is the hormones produced by this gland which controls the entire metabolic mechanism of the body. Iodine is a micronutrient which is necessary for the thyroid gland to synthesise its hormones and for a long time, iodine deficiency used to be the commonest cause of hypothyroidism in the State..
But several studies conducted in Kerala in recent times have shown that with the widespread use of iodised salt, there is iodine sufficiency in the community.
“Infertility is just one end of the spectrum of problems caused by a low functioning thyroid gland. Our hospital data points out that in nearly 25 per cent of infertility cases, hypothyroidism has been a significant contributing factor. At the other end of the spectrum, we are also up against high levels of maternal hypothyroidism,” says Sheila Balakrishnan, Associate Professor of Gynaecology, SAT hospital.
Hypothyroidism in pregnant women has been associated with many complications and if left untreated could lead to pre-eclampsia, pre-term labour and post-partum haemorrhage. For the babies too, there are risks of foetal distress and congenital abnormalities.
About 8 to 10 per cent of mothers coming to SAT hospital have been found to have hypothyroidism and the main cause is no longer iodine deficiency, but Hashimoto’s thyroiditis or autoimmune thyroiditis.
Hashimoto’s disease or autoimmune thyroiditis is a condition wherein the body itself produces antibodies, which react against the proteins in the thyroid gland, slowly destroying the gland and making it unable to produce the vital thyroid hormones that the body requires.
“The spectrum of thyroid diseases in the State has now shifted to the autoimmune diseases. But we cannot be sure if we are seeing a rising incidence or if we are just picking up more cases now. Because women are now regularly screening for thyroid diseases and the physicians are also more aware of hypothyroidism caused by autoimmunity,” says Mathew John, a busy endocrinologist in the city.
A study conducted in 2009 by the Department of Endocrinology and Diabetes, Amrita Institute of Medical Sciences among 1000 women above 35 years of age in Kerala indicated thyroid functional disorders in 19.6 per cent. Significantly, the study found that 9.5 per cent of the total subjects had thyroid antibodies but they were asymptomatic or their hypothyroidism was sub clinical. Among those women in the study group who had hypothyroidism, the prevalence of thyroid antibodies or autoimmunity was 46 per cent.
K. P. Poulose, former Professor of Medicine and Consultant General Physician at SUT Hospital here, who recently studied the prevalence of thyroid autoantibodies in 125 women between 15 and 35 years of age, without any known thyroid disease, has reported finding thyroid auto antibodies in 112 of the subjects (89.6 %). All of these subjects with a family history of thyroid disorders in their first degree relatives had thyroid antibodies.
“All these women are likely to develop thyroid disorders in future and the antibodies they carry would be passed on the next generation. We screened separately, 20 pregnant women who had hypothyroidism due to antibodies or autoimmunity and found that 15 of the babies had either one or both thyroid antibodies. These children should be followed up in future because they are likely to develop hypothyroidism,” Dr. Poulose says. He says that about 60 per cent of the women who had thyroid antibodies were asymptomatic .
“Hypothyroidism due to autoimmunity never used to be more that 6 to 10 per cent. But these days, almost 70 per cent of hypothyroidism cases are attributed to autoimmunity,” he adds.
Autoimmune hypothyroidism requires lifelong treatment. But Dr. Mathew John says that not all of those found to be having thyroid antibodies require treatment. “Treatment is required only if the antibodies lead to a dysfunction of the thyroid gland. But often , those who start treatment, never comes back for periodic reviews. Autoimmunity runs in families and is passed on from the mother to the girl child,” Dr. John says.
At present, in the Government health system, there is no routine screening of pregnant women for hypothyroidism but there are many like Dr. Sheila, who feels that may be it was time that the State drew up its own guidelines regarding this. Because even the mildest of hypothyroidism during pregnancy can adversely affect the development of the baby.
The reasons for the high incidence of Hashimoto’s disease or thyroid autoimmunity is still not known. However, in 2006, the New England Journal of Medicine reported that while iodine supplementation through iodised salt was one of the most beneficial public health interventions to have taken off, “excess iodine intake can lead to autoimmune thyroiditis”. But the same issue also had an editorial by the late Robert Utiger, renowned physician at the Harvard Medical School that the “small risks of chronic iodine excess are outweighed by the substantial hazards of iodine deficiency.”