Hypothyroidism- An Overview
What is hypothyroidism?
Hypothyroidism is a condition in which our body is unable to synthesize enough thyroid hormones. Thyroid hormones help control growth,cell repair and metabolism. As a result, the people with inadequate thyroid hormones (i.e:hypothyroids) experience tiredness,hair loss,weight gain,cold intolerance,depressed and many other symptoms.
Hypothyroidism affects 1-2% of people worldwide and is 10 times more likely to affect women then men.
Thyroid gland(in brief)
It is a small butterfly shaped endocrine gland situated in the front of neck,consisting of two lobes connected by an isthmus. The thyroid gland secretes thyroid hormones,which primarily influence the metabolic rate and protein synthesis. The thyroid hormones triiodothyronine(T3) and thyroxine(T4) are synthesized from iodine and tyrosine(an amino acid).
The release of thyroid hormones from the thyroid gland is regulated by thyroid stimulating hormone(TSH) secreted from the anterior pituitary. The release of TSH itself is regulated by by thyroid releasing hormone(TRH) produced by the hypothalamus. Hyperthyroidism occurs when the gland produces excessive amounts of thyroid hormones. In contrast,hypothyroidism occurs when the thyroid gland produces insufficient thyroid hormones. Hypothyroidism caused by inadequate function of the thyroid gland itself is primary hypothyroidism,due to inadequate stimulation by TSH from the pituitary gland is secondary hypothyroidism and due to inadequate release of thyrotropin releasing hormone hormone from the hypothalamus is tertiary hypothyroidism.
Worldwide the most common cause of hypothyroidism is iodine deficiency. But in iodine sufficient regions, the most common of hypothyroidism is hashimoto’s thyroiditis-an autoimmune disease. Other causes include congenital abnormalities, diseases causing transient inflammation, surgical removal or radio ablation of the thyroid, the drugs amiodarone and lithium, amyloidosis and sarcoidosis.
Hashimoto’s disease also known as chronic lymphocytic thyroiditis or autoimmune thyroiditis, in which the immune system attacks the body’s own cells and organs. Thyroiditis-an inflammation of the thyroid gland,causes thyroid hormones to leak into the blood raising their overall levels and leading to hyperthyroidism. After 1-2 months this may develop into hypothyroidism. Congenital hypothyroidism-the thyroid gland does not function properly from birth.
DIET FOR HYPOTHYROID PATIENTS
Individuals should follow a varied, well-balanced diet that is not high in fat or sodium. Individuals should also avoid eating highly processed foods(cakes,cookies), as they usually contain a lot of calories and may gain weight easily. In addition,those with hashimoto”s may benefit from following a gluten-free diet. Some other foods and nutrients that may be hazardous especially if consumed in large quantities include:
- soya,as it can affect thyroxine absorption.
- iron supplements as they can affect thyroxine absorption.
- cruciferous vegetables such as cauliflower,kale,and cabbage (these may contribute to a goiter when taken in large amounts).
- certain fruits such as peaches,pears and strawberries.
- beverages such as coffee,green tea and alcohol(these may irritate your thyroid gland)
Some natural remedies are proposed for hypothyroidism, but it is important to a doctor first, because the treatment for thyroid problems must be delicately balanced.
Selenium: people with some types of thyroid problem may benefit from taking selenium. But the deficiency or the excess of this micronutrient may be associated with adverse outcomes,it should be taken in consideration very carefully.
Vitamin D: deficiency has been linked with severity of disease in hashimoto’s.
Additionally,for those with autoimmune and inflammatory thyroid conditions,supplements such as turmeric(containing at least 500 mg cur cumin)and omega-3s may help to improve inflammation.
Doctors usually take a medical history,carry out a physical examination and watch for laboratory reports. Doctors look for the enlarged thyroid gland in the neck.It is clearly visible as a butterfly shaped.
TSH test: If the TSH reading is above normal,the patient may have hypothyroidism. If the TSH levels are below normal,the patient may have hypothyroidism or hyperthyroidism.
The T3,T4 and thyroid autoantibody tests are the additional blood tests used to confirm the diagnosis.
Tests to check the cholesterols levels,liver enzymes,prolactin,and sodium may also be carried out(but not often).
Increased demands on metabolism during pregnancy results in increased demands on the thyroid. If hypothyroidism occurs during pregnancy,it is usually due to Hashimoto’s disease. This condition affects between 3-5 out of every 1,000 women during pregnancy.Uncontrolled hypothyroidism increases the risk of miscarriage,preterm delivery,and a rise in blood pressure during late pregnancy or preeclampsia. It can also affect brain development and growth rates.
Management In Pregnancy: Serum TSH levels are to be closely monitored.
The treatment goals for hypothyroidism are to reverse clinical progression and correct metabolic derangements,as evidenced by normal blood levels of thyroid stimulating hormone(TSH) and free thyroxine(T4). Thyroid hormone is administered to supplement or replace endogenous production. In general,hypothyroidism can be adequately treated with a constant daily dose of levothyroxine(LT4).
For young and healthy individuals thyroid hormone can be started as full replacement dose (adjusted by weight). But elderly patients and those with known ischemic heart disease, treatment should begin with one fourth to one half the expected dosage, and the dosage should be adjusted in small increments after no less than 4-6 weeks. Lower doses may be sufficient in those with subclinical hypothyroidism, while people with central hypothyroidism may require a higher than average dose.
For most cases of mild to moderate hypothyroidism, a starting levothyroxine dosage of 50-75micro gram/day will be sufficient. However we should select the dose in accordance with patients weight. TSH is not a reliable marker of hormone replacement and decisions are made on he basis of freeT4 level in people with central/secondary hypothyroidism. Levothyroxine is best taken 30-60 minutes before breakfast,or four hours after food,as substances such as food and calcium can inhibit the absorption of levothyroxine.
Add liothyronine (synthetic T3) to levothyroxine to provide better symptom control. People with hypothyroidism who do not feel well despite optimal levothyroxine dosing may request adjunctive treatment with liothyronine.
Desiccated Animal Thyroid :
Desiccated animal thyroid is an animal based thyroid gland extract mainly from pigs. It is a combination therapy ,containing forms of T4 and T3. It also contains calcitonin,T1 and T2 which are not present in synthetic hormone medication. Previously it was a mainstream hypothyroidism treatment,but its use now is unsupported by the evidence.
Myxedema coma :
It usually requires admission to the intensive care,close observation and treatment of abnormalities in breathing,temperature control,blood pressure,and sodium levels. Provide mechanical ventilation. For rapid treatment ,levothyroxine or liothyronine may be administered intravenously,particularly if the level of consciousness is too low to be able to safely swallow medication.
*Do not stop the medication abruptly,it requires tapering dose.
*Take medicene at early morning (empty stomach).
*Do not take thyroid medications within 4 hours of GI medications (e.g:Aluminium Hydroxide-these decrease the absorption of go thyroid medications)
Originally written by: Ganesh lamichhane (MBBS, third year , JMC)