Hyperthyroidism is defined as a condition where excess of thyroid hormones are produced by the thyroid gland. The term ‘Thyrotoxicosis’ refers to an excess of thyroid hormones in the blood.
As the name suggests, there is excess of thyroid hormones (T3- thyroxine and T4 -triiodothyronine) that are responsible for metabolism in our body and help maintain the overall BMR. Thus, an excess of these hormones speeds up the metabolism and exacerbates the sympathetic nervous system and results in symptoms resembling an adrenaline rush!
Signs and Symptoms
The hyped up body metabolism may present as:
In the elderly it may present as apathetic thyroidism and can be mistaken for depression. Also, since majority of elderly are on beta blockers, which are used to control High BP, many signs of hyperthyroidism may be masked.
- Tachycardia, palpitation (pounding heart beats), worsening of angina/heart failure, atrial fibrillation (irregular heart rate).
- Weight loss in spite of voracious appetite, frequent bowel movements.
- Fine tremors, fatigue, generalized weakness, weakness in muscles of thigh and upper arm, hyperreflexia.
- Insomnia, hyperactivity, irritability, impaired concentration, nervousness and psychosis.
- Excess sweating, heat intolerance and warm, moist skin.
- Menstrual irregularities, loss of libido
- Brittle bones (Oestopenia).
- Enlarged thyroid gland that moves with swallowing
- Staring look of the eyes and lid lag
- Exopthalmos ( protruding eye balls), lid lag, excess tearing, grittiness, diplopia and loss of vision
- Indurated pink-orange skin like plaque over lower leg (Thyroid Dermatopathy)
- Grave`s disease
- Toxic multinodular goiter
- Toxic adenoma
- Iodine excess: Jod-Basedow Phenomenon
Thyotoxicosis without hyperthyroidism
- TSH secreting pituitary adenoma
- Gestational thyrotoxicosis
- Thyroid destruction by amidarone, radiation etc.
- Excessive ingestion of thyroid hormone
This is the most common form of hyperthyroidism. It auto-immune mediated and is shown to run in families. Symptoms 10 and 11 are exclusive to patients with Grave’s Disease. It is more common in women between 20 to 50 years of age and is associated with high iodine intake. Stress is a major trigger factor. It is also found to be associated with myasthenia gravis in 5% cases.
- Blood investigation for TSH, T3, T4: high T3 & T4 and low TSH suggest hyperthyroidism.TSH < 0.5 with normal T3 and T4 levels is termed as subclinical hyperthyroidism and regular follow up is required.
- (TSH (units): 0.45 - 4.50 uIU/mL; T4 Free/Direct (nanograms): 0.82 - 1.77 ng/dl; and T3 (nanograms): 71 - 180 ng/dl.).
- In grave`s disease Anti –TPO levels (normal 0-40 IU/ml). or Anti TSH levels
- Thyroid scintigraphy is a useful test to characterize (distinguish between causes of) hyperthyroidism, and this entity from thyroiditis. This test procedure typically involves two tests performed in connection with each other: an iodine uptake test and a scan (imaging) with a gamma camera.
- Anxiety and panic attacks
- Pheochromocytoma (tumor of adrenal gland )
- Weight loss due to malignancy
- Chronic alcoholism
Side effect - sore throat and hypothyroidism
- Antithyroid drugs: Carbimazole and propylthyrouracil. Symptoms usually improve in 4 to 6 weeks but the treatment may take from 6 months to 2 years. A very high dose is often needed early in treatment, but if too high a dose is used persistently, patients can develop symptoms of hypothyroidism. Accurate titering of dose in often difficult which is why sometimes, a "block and replace" attitude is taken.
- Side effects- rash, urticaria, liver failure and agranulocytosis
- Beta blockers
- Radioactive iodine- radioactive iodine-131 is given orally (either by pill or liquid) on a one-time basis to severely restrict, or altogether destroy the function of a hyperactive thyroid gland. The Beta rays of radioisotope iodine destroy the gland. The principal advantage of radioiodine treatment for hyperthyroidism is that it tends to have a much higher success rate than medications. Depending on the dose of radioiodine chosen, and the disease under treatment (Grave's vs. toxic goiter vs. hot nodule etc.), success rate in achieving definitive resolution of the hyperthyroidism may vary from 75-100%.
Contraindicated - in pregnancy and breast feeding
Subtotal thyroidectomy -may be performed to replace medication, or in cases where it is preferred over radioactive iodine. It is also indicated when the gland is excessively enlarged.
Side effects - Recurrent Laryngeal Nerve Palsy (hoarse voice), hypoparathyroidism and hypothyroidism.
Treatment for Graves Opthalmopathy:
- Mild signs and symptoms can be managed by avoiding wind and bright lights, using artificial tears or lubricating gels, wearing dark glasses and raising the head end of the bed. In severe cases, corticosteroids may be tried.
- Surgical options include: Orbital decompression and eye muscle alignment surgery.
Thyroid storm presents with extreme symptoms of hyperthyroidism. It is treated aggressively with resuscitation measures along with a combination of the above modalities including intravenous beta blockers such as propranolol, followed by a thionamide such as methimazole, an iodinated radiocontrast agent or an iodine solution if the radiocontrast agent is not available, and an intravenous steroid such as hydrocortisone.
Gestational Hyperthyroidism is a transient state of Hyperthyroidism observed in early pregnancy characterized by severe nausea, vomiting and weight loss. Antithyroid drugs are rarely needed, and fluid replacements suffice until condition resolves. Lifestyle modifications:
- A diet high in calories and proteins
- Relaxation techniques like yoga
- Adequate intake of vitamins and calcium