Congenital Hypothyroidism

In the recent past, I met a harrowed young couple, whose newborn boy was just diagnosed with congenital hypothyroidism by the paediatrician. Listed below are some of the most common questions that all parents with children of congenital hypothyroidism have. I am penning down the questions the couple asked me and the answers that I could give. .What is the thyroid gland and what couple, whose newborn boy was just diagnosed with congenital hypothyroidism by the paediatrician. Listed below are some of the most common questions that all parents with children of congenital hypothyroidism have. I am penning down the questions the couple asked me and the answers that I could give.What is the thyroid gland and what does it do?The thyroid is a small gland that can be found beneath the skin and muscles at the front of the neck. Think of the spot where a bow tie would rest. The gland is brownish-red in colour and features left and right halves (called lobes) that look like a butterfly's wings. Normally, the thyroid gland weighs less than thirty grams and helps in several bodily functions. This important gland produces the thyroid hormones, which primarily consist of thyroxin (T4) with a small (10 per cent) amount of tri-iodothyronine (T3). Thyroid hormones play an essential role in brain development in infancy and facilitate normal growth in childhood and adolescence.What is hypothyroidism?Hypothyroidism (or underactive thyroid) is a dysfunction that results in the thyroid gland not making enough of some important hormones. This results in the body using energy sluggishly, and there is a slow-down of metabolism in our body cells.Hypothyroidism disproportionately affects adult women.What is congenital hypothyroidism?Children suffer from hypothyroidism as well. It is a partial or complete loss of function of the thyroid gland (hypothyroidism) that affects infants from birth (congenital).Congenital hypothyroidism is a condition resulting from an absent or underdeveloped thyroid gland or, one that has developed but cannot make thyroid hormone because of a 'production line' problem. Babies suffering from this condition cannot produce enough thyroid hormone for their body's needs.Congenital hypothyroidism also goes by the name cretinism or congenital myxoedema.What are the types of congenital hypothyroidism?In 80 to 85 per cent of cases, the thyroid gland is absent, severely reduced in size, or abnormally located. These cases are classified as thyroid dysgenesis. In the remainder of cases, a normal-sized or enlarged thyroid gland (goitre) is present, but the production of thyroid hormones is deficient or absent. Most of these cases occur when one of several steps in the hormone synthesis process is disturbed; these cases are known as thyroid dyshormonogenesis. Rarely, reduction or absence of thyroid hormone production is caused by impaired stimulation of the production process by a structure at the base of the brain called the pituitary gland. These cases are identified as central or pituitary hypothyroidism.What causes congenital hypothyroidism?Thyroid gland development in a foetus begins very early in pregnancy. The gland begins to form at the back of the tongue and moves to its normal position in the lower neck by eight weeks of gestation.Sometimes the gland does not develop properly and/or may not make it to the normal position and remains lodged at a different place. Rarely, iodine deficiency can predispose to the development of congenital hypothyroidism..Sometimes the gland does not develop properly and/or may not make it to the normal position and remains lodged at a different place. Rarely, iodine deficiency can predispose to the development of congenital hypothyroidism.Is there anything I mishandled during my pregnancy that made my child hypothyroid?No, please don't feel guilty about anything. In most cases, doctors don't know the cause and there is no way to prevent it.How common is congenital hypothyroidism?Congenital hypothyroidism occurs in approximately 1:500 to 1:1500 new-born, across India. It occurs in people of all ethnic groups around the world.What are the symptoms of congenital hypothyroidism?The clinical features of congenital hypothyroidism are often subtle and many newborn infants remain undiagnosed at birth. This is because they are protected by their mother's thyroid hormone for a few weeks after birth. After about three to four weeks of age, babies must rely solely on their thyroid hormones. If they don't make enough, symptoms will show up at that time. A small number of babies with congenital hypothyroidism do show effects at birth, however. Some babies have a yellow colour to their skin or the whites of their eyes. This is called jaundice. Other signs that may occur in early infancy include:• Low activity level - babies sleep more than usual and don't move as much• Poor feeding and a poor suck• Fewer bowel movements or constipation• Floppy muscle tone (muscle weakness)• Swelling around the eyes and a puffy face• Large swollen tongue• Cool, pale, dry skin• Large soft spot on the skull (the fontanel that closes late)• Large belly with protruding navel (umbilical hernia)What problems can occur if congenital hypothyroidism is not treated?If left untreated, babies may develop some or all of the following effects over time:• Coarse, swollen facial features• Breathing problems• Hoarse-sounding cry• Delay in sitting, crawling, walking, talking (delayed milestones)• Wide and shorter hands• Poor weight gain and growth• Goitre (enlarged thyroid gland causing a lump in the neck)• Anaemia• Slow heart rate• Fluid build-up under the skin (called myxoedema)• Hearing lossChildren who remain untreated usually develop intellectual disabilities and are much shorter than the average. They may have muscle stiffness and an unsteady gait. Most have a speech delay and some have behaviour problems.What is the treatment for congenital hypothyroidism?The main treatment for congenital hypothyroidism is thyroid hormone replacement. It is safe and easy to take. If it is begun immediately after a child is diagnosed, treatment can prevent many or all of the effects of congenital hypothyroidism. If damage to the brain and nerves happens because treatment is delayed, it is usually permanent and cannot be reversed.You may seek the consultation of a paediatric endocrinologist (a doctor with training in treating children with thyroid and other hormone problems) to look after your child.There are a few important facets of managing a child with congenital hypothyroidism:MedicationL- thyroxin is a synthetic form of thyroid hormone naturally made by the body. This medication is given in tablet form to all babies with congenital hypothyroidism. Yourdoctor and endocrinologist will decide how much L-thyroxin your baby needs and how often. He or she will increase the amount of medication as your child grows. L-thyroxin replacement is a life-long treatment.L-thyroxin tablets are tiny and can be crushed and mixed with food or dissolved in a small amount of formula, juice, or other liquid. Avoid dissolving in a larger volume of liquid, as your child may not finish it all and thus receive a suboptimal dose of L-thyroxin. There is no approved liquid form of thyroid hormone for babies.It is important to give your child the correct amount of L-thyroxin decided by your doctor. Excessive dosing can cause:• Rapid heart rate• Diarrhoea• Lack of sleep• ShakinessPlease remember that synthetic L-thyroxin is the safest form of medication to use. If you are giving soy-based formula and iron supplements to your baby, do inform the treating doctor as these can interfere with the absorption of L-thyroxin.MonitoringYour child will require frequent examination by the treating doctor for monitoring the baby's physical and intellectual development. If the child shows delayed milestones or specifically delays in certain areas of learning or speech, qualified counsellors can be arranged.If the treatment for congenital hypothyroidism is started soon after birth, the child can have normal growth and can live a healthy life. If treatment is initiated late, developmental delays or learning problems may ensue.Is our child1s congenital hypothyroidism an inherited disease?In about 15 per cent of cases of congenital hypothyroidism, the thyroid gland appears normal but fails to make adequate amounts of thyroid hormone. These cases are more likely to be inherited, but not always. Most of the hereditary types of congenital hypothyroidism are inherited in an autosomal recessive manner. This type of inheritance affects both boys and girls equally. To get further information regarding the inheritance of congenital hypothyroidism, an option of genetic counselling and prenatal testing in a subsequent pregnancy is available. If any inherited pattern of congenital hypothyroidism is suspected, genetic testing on a blood sample can be performed to determine the gene changes responsible for the ailment. However, please note that the risk of having another child with this type of congenital hypothyroidism is low.What are the basic tests available for making a diagnosis of congenital hypothyroidism?Blood tests to detect the amount of thyroid hormone (T4) and thyroid-stimulating hormone (TSH) are routinely done to confirm the diagnosis of congenital hypothyroidism.Ultrasound examination of the neck enables the ultrasonologist to determine the presence of the thyroid gland; its location, shape and size.Dr Vinod K. Abichandani is a Diabetes andEndocrine Physician in Ahmedabad.