Thyroid gland is an important member of the endocrine system. Hormones produced from the gland influence almost all the organs and systems of the body. Thyroid hormones help in basic metabolic functions, like utilisation of energy, and maintenance of normal body temperature. These are essential for the normal functioning of vital organs like brain, heart, muscles, and other organs.
Where is thyroid gland in our body?
Thyroid gland is a small butterfly shaped organ, that lies just in front of our trachea, i.e. wind pipe, and just below our larynx, i.e. our voice box. In males, its’ location can be easily identified below the Adam’s apple in the front of neck.
What are the hormones produced from our Thyroid gland?
The thyroid gland acts under the influence of a hormone, Thyroid stimulating hormone(TSH), secreted from our Pituitary gland in the brain, to produce two hormones, T3 and T4. The production of thyroid hormones is kept under check by a negative feedback loop. So if level of T3 and T4 in blood is high, it Pituitary decreases production of TSH, thereby decreasing levels of thyroid hormones and vice versa.
What is Hypothyroidism?
Hypothyroidism is a clinical state when the level of thyroid hormone in blood is low. It can be because of a disease of thyroid gland producing reduced amount of hormones, called primary hypothyroidism, or because it is not receiving enough signal from the Pituitary gland, called secondary hypothyroidism.
The prevalence of clinical hypothyroidism worldwide is roughly 4-5%, which means 1 out of every 20 persons will have reduced levels of thyroid hormones in the body. Subclinical hypothyroidism is present in 15-20% of all individuals.
How does hypothyroidism manifest?
Hypothyroidism can manifest in multiple forms, depending upon age and gender. The following symptoms and signs may present in a combination of forms. One of the most common complaint is feeling of excessive tiredness, and weight gain.
• Dry skin
• Feels too cold
• Hair loss
• Difficulty concentrating and poor memory
• Weight gain despite poor appetite
• Husky voice
• Menorrhagia (Oligomenorrhea or amenorrhea in long standing patients)
• Frequent miscarriages
• Dry coarse skin
• Cold hands an feet
• Puffiness of face, hands, and feet
• Diffuse alopecia
• Bradycardia/Slowing of pulse rate
• Peripheral edema
• Delayed tendon reflex relaxation/Hung up Patellar reflex
• Carpal tunnel syndrome, and other entrapment neuropathies
Your doctor will examine your neck also, for any enlargement, tenderness, or nodularity of your thyroid gland.
Who are prone for hypothyroidism?
• Females are more affected than males.
• People living in endemic Iodine deficient areas.
• Patients who have undergone removal of partial or complete thyroid gland, for goiter or malignancy, so called Iatrogenic hypothyroidism.
• Certain Autoimmune disorders like Hashimoto’s thyroiditis.
• Patients having pituitary tumors, and undergoing surgery
• Patients on certain drugs like Lithium
• Congenital hypothyroidism, caused by developmental lack of thyroid hormones.
What tests are done to diagnose hypothyroidism?
Thyroid function tests include estimation of TSH, and levels of T3 and T4 hormones in the blood.
First step is to determine whether TSH is suppressed, normal, or elevated. Normal TSH level essentially excludes a primary abnormality of thyroid function. Currently, fourth generation TSH assays have greatly enhanced the accuracy of measurements of TSH levels. However, for clinical use third generation assays are adequate.
Finding an abnormal TSH, the next step is to measure levels of circulating thyroid hormone levels. Radioimmunoassays are widely available for serum total T4 and total T3. The assays for total T4 and T3 levels also measure hormones in bound state, which means the hormone that is bound to proteins in plasma, and is not biologically active. Therefore, measurement of free T3 and T4 is more accurate in terms of knowing the active hormone level. Assays are also available to measure free T3 and T4 levels, directly or indirectly.
What is Subclinical hypothyroidism?
Subclinical hypothyroidism is a clinical state when the level of you TSH is high against a background of normal levels of circulating thyroid hormones. It can affect roughly 4-10% of individuals, depending upon gender, age, and `race.
The thyroid hormones are normal, but TSH levels are high. Based on TSH levels subclinical hypothyroidism can be classified into mild increase <10mU/l, with or without clinical symptoms of hypothyroidism, and more severe increase in TSH >10mU/l.
What is treatment of Subclinical Hypothyroidism?
In individuals with TSH <10mU/l, without symptoms, simple observation with repeat hormonal profile after 3 months is advisable. If clinical symptoms of hypothyroidism are present, then trial of replacement therapy for 3 months is advisable with monitoring of resolution of clinical symptoms.
Individuals with TSH levels >10mU/l, are treated with replacement therapy, Levothyroxine.
What is the treatment of hypothyroidism?
Levothyroxine is the treatment available for hypothyroidism.
The drug is started in small dose and is adjusted on the basis of TSH levels. The level of TSH is repeated and the goal of treatment is a normal TSH, which ideally should be in the lower half of the reference range.
TSH responses are gradual and should be measured about two months after instituting treatment or after any subsequent change in levothyroxine dosage.
Clinical symptoms with replacement therapy are slow to disappear, and may take couple of months, while full resolution of symptoms may take from 3-6 months, even after TSH levels have returned to normal.
How should I take my Levothyroxin?
Levothyroxine tablets are to be taken on an empty stomach, as food interferes with the absorption of the tablet. It should be taken 30 minutes to one hour before breakfast everyday. There are different brands of levothyroxine available. Do not change brands without first consulting your doctor or pharmacist.
What if I miss my dose of Levothyroxine tablet?
Levothyroxine has a long half-life (7 days), patients who miss a dose can take two doses of the skipped tablets at once, without any side effects.
I am pregnant, and hypothyroid. What should I know?
Having adequate circulating levels of thyroid hormones is very important for the development of the fetus. Consult an obstetrician, as soon as you think you may be pregnant. Thyroid function should be evaluated immediately after pregnancy is confirmed. Thyroid hormones levels should be repeated at the beginning of the second and third trimesters.
Your dose of levothyroxine may need to be increased by 50% during pregnancy and returned to previous levels after delivery.
Disclaimer- This article is meant only for general public awareness and basic understanding. This text can not replace expert medical advice. Please visit your physician if you think you may be hypothyroid.