By Dr Maanvizhi Kandaiah
 

The Thyroid is a butterfly shaped endocrine gland situated in the front of one’s neck (pictured below). The hormones thyroxin (T4) and Triode thyronine (T3) secreted by this gland are responsible for proper functioning of various organs and systems in our body.
Disorders of thyroid are common. Under-secretion of thyroid hormones is called hypothyroidism and is commonly found affecting over 1% of general population and 5% of individuals above 60 years; especially in females. Over-secretion of thyroid hormones is called hyperthyroidism.
 
HYPOTHYROIDISM (MYXOEDEMA)
There are several causes of hypothyroidism such as congenital (since birth) , due to iodine deficiency, auto immune thyroiditis (common cause),following surgery of thyroid gland and radioactive iodine treatment, due to infiltration of thyroid gland in diseases like scleroderma, amyloidosis and so on. Some have a Goitre (swelling of thyroid gland) while majority are without a Goitre. There are also some special situations like after childbirth, when a transient thyroid disturbance can occur and is called postpartum thyroiditis.
Hypothyroidism is diagnosed by checking the blood level of Thyroxine (T4) which is low and the level of TSH (Thyroid stimulating Hormone) a signalling hormone from the brain which is found in high levels.
 
SYMPTOMS ANS SIGNS: Hypothyroidism causes a wide range of symptoms like lethargy, tiredness, weight gain, cold intolerance, excess sleep, constipation, swelling of face and legs, hoarseness of voice, muscle aches and pains, numbness in hands (carpal tunnel syndrome), dry skin and hair loss, depression, loss of memory, menstrual irregularities in women, most of which are very subtle and hence the disease goes undetected for years. The classical appearance of myxoedema with thick, dry skin and mask like expressionless face occurs only in the late stages of the disease. Routine screening tests for thyroid function is recommended in the following group of people:
 Suspected swelling of thyroid gland (goitre)
 Previous history of thyroid surgery or radiation treatment to the neck region for other conditions like cancer of neck.
 Women presenting with infertility, abnormal menstrual cycles, history of repeated abortions
 In patients with Diabetes type 1 — Insulin dependent diabetes and type 2 diabetes
 In patients with very high cholesterol levels
 In elderly women with non-specific symptoms like tiredness, depression, loss of memory and obesity
 In patients who are under treatment with medications like amiodarone (given for cardiac problem), lithium, interferon therapy for Hepatitis C.
 In pregnant women with family history of thyroid disease or previous history of thyroid abnormality and in Type 1 diabetes, it is recommended to check the thyroid function at an early stage, when they plan for pregnancy.
 
EFFECTS OF HYPOTHYROIDISM ON PREGNANCY AND CHILDBIRTH
Undiagnosed or inadequately treated hypothyroidism in the pregnant women may lead to higher incidence of abortion, anaemia, still-birth, excess bleeding after child birth and mainly impaired neurological development in the baby leading to low IQ scores.
A woman with pre-existing hypothyroidism should consult her doctor as soon as she thinks she is pregnant. At diagnosis of pregnancy, the dose of Thyroxine is usually increased by 25 to 50mcg immediately, before she meets a specialist, in order to meet the increased demand during pregnancy.
Her thyroid function tests need to be checked frequently during pregnancy, at least once in each trimester (three months) or more frequently during the first three months. It is important to maintain the TSH level in the low normal range (0.4 to 2.0mu/L) during pregnancy, to ensure proper neurological development of the growing baby.
POSTPARTUM THYROIDITIS
This is a condition seen in 5 to 10% of women within six months after
delivery of a baby. There is an initial phase of excess thyroid activity followed by deficiency of thyroid hormones. 50% of such women may go for permanent hypothyroidism over a period of 7 years. Recurrence is common in subsequent pregnancies up to 70%.
 
SUBCLINICAL HYPOTHYROIDISM
In this condition, the patients are mostly without any symptoms or very mild symptoms and the blood tests show normal level of thyroxine with slight raised level of the signalling hormone, TSH. The doctors decide on the treatment based on other associated factors. These patients need to follow up their thyroid functions on regular basis, since they may go in for frank hypothyroidism at later stages.
 
TRANSIENT THYROIDITIS
This is due to a temporary inflammation of the thyroid gland caused by a virus. Usually causes pain in the region of thyroid gland with temporary raise in the level of thyroxine in blood, followed by deficiency later. It is common in women of age 20 to 40 years. It is managed by pain killer medications and steroid medications with periodic follow up of thyroid functions.
 
COMPLICATIONS OF HYPOTHYROIDISM
 There is an increased risk of coronary heart disease and cardiac failure. A patient with a known history of heart disease has to be started on a very low dosage of thyroxine tablet under supervision by a specialist, since sudden death and risk of myocardial infarction (heart attack)is high in such patients.
 
  Increased susceptibility to infections.

 Mental illnesses such as psychoses can occur-Myxedema madness.

 Miscarriages, pre-term delivery, excess bleeding can occur during pregnancy.

 Rarely a life threatening condition called Myxedema coma with a 40% death rate can occur. Such patients suddenly go into deep stupor and coma with low blood pressure, low body temperature, low blood sugar and convulsions
 
TREATMENT OF HYPOTHYROIDISM
Hypothyroidism is treated by replacement with thyroxine tablets, which are to be taken on a regular basis on empty stomach; usually lifelong. The doctor will adjust the dosage of Thyroxine based on the levels TSH in the blood. This test has to be done once in two to three months after a change in the dosage. Once stabilised, the Thyroid function tests are to be repeated every year to make sure that the dosage is still correct.
 
HYPERTHYROIDISM
This is a condition where there is excess of Thyroxine (T4) in the blood with low levels of TSH. This causes symptoms such as excess appetite, weight loss, shaky hands (Tremors), anxiety, lack of sleep, irritability, fast heart rate, frequent bowel movements, prominent eye balls etc. Once detected, hyperthyroidism needs to be evaluated further and managed by a Specialist. The causes are varied such as autoimmune (Grave’s disease), thyroid nodule, multinodular goitre, malignancy etc. Management of hyperthyroidism depends on the cause and usually is by radioactive iodine treatment, surgery or by anti-thyroid drugs in young people.
 
SUMMARY
Disorders of thyroid gland is very common and classical signs and symptoms appear late in the disease. People with high risk should be evaluated early to pick up the disease in early stage and for proper management.
 
l The author is General Scope Physician
at Aster Musherib.