MAYA C/THE HINDU
Children with low IQ or problems of poor growth should be evaluated for thyroid function because their growth retardation could be due to a low-functioning thyroid gland or hypothyroidism.
For a long time, iodine deficiency used to be the main cause of hypothyroidism. However, iodine supplementation through universal salt iodisation has taken care of the iodine deficiency-induced hypothyroidism.
But mild cognitive defects or poor memory in children despite iodine sufficiency could be due to sub-clinical hypothyroidism, caused by the presence of thyroid auto-antibodies. Rather than treating them as dullards, these children should be screened for hypothyroidism, says K.P. Poulose, former Professor of Medicine and Consultant General Physician at SUT Hospital, Thiruvananthapuram.
In fact, all schoolchildren with consistent poor grades should be mandatorily screened for thyroid function, Dr. Poulose feels. Early identification and treatment can make marked improvement in these children.
Hypothyroidism caused by the presence of thyroid auto-antibodies or autoimmune thyroidism (also known as Hashimoto’s thyroiditis) has emerged as a major cause for thyroid dysfunction in a significant number of patients in Kerala in recent times.
This 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 for all metabolic processes.
If some three decades ago, autoimmune thyroidism accounted for only 7 per cent of the thyroid dysfunction disorders, now, almost 70 per cent of these cases are due to autoimmunity.
“Hypothyroidism is the commonest cause for mild mental and growth retardation in children. Especially for children with short stature, we routinely screen them for hypothyroidism, even though there is no recommendation about mandatory screening. We test them for the presence of thyroid auto-antibodies too if the thyroid function test is mildly abnormal. About four per cent of the children who are tested positive for antibodies will go on to develop hypothyroidism every year,” says Mathew John, a consultant Endocrinologist in the city.
Children born to mothers with autoimmune hypothyroidism are highly likely – the chances are about 75 per cent – to have the thyroid antibodies passed on from the mother. These children might not have hypothyroidism at the time of birth but could subsequently develop the condition. Autoimmune thyroidism runs in families. As part of a recent study to assess the prevalence of thyroid antibodies in the families of patients with autoimmune hypothyroidism, doctors at SUT Hospital screened 111 relatives – children, siblings and parents – of 70 patients. These subjects did not have any apparent symptoms.
“We found that 95 out of the 111 (86 %) had thyroid antibodies and 41 (43 per cent) already had hypothyroidism. Out of the 41 subjects with hypothyroidism, 24 were newly detected during our examination,” Dr. Poulose says.
Screening newborns for congenital hypothyroidism (caused by a dysfunctional thyroid gland) is mandatory as it is the commonest cause of preventable mental retardation in children.
Realising the public health importance of screening for congenital hypothyroidism, last year, the government introduced this test as part of the new-born screening programme for six preventable metabolic conditions in 44 selected hospitals in the State where deliveries are conducted.
May 25 was World Thyroid Day