Definition of  Hyperthyroidism :

Definition : Hyperthyroidism is the term used for overproduction of the hormones by thyroid gland. In hyperthyroidism pathology is in thyroid gland itself.

Causes of hyperthyroidism :

1. Diffuse toxic goitre (Grave’s disease).
2. Toxic multinodular goitre.
3. Autonomous nodule
4. TSH secreting pituitary tumour.
5. Functioning thyroid cancer/metastasis.
6. Exogenous
7. Thyroiditis.

Definition of thyrotoxicosis :

Definition : Thyrotoxicosis is symptom complex due to raised levels of thyroid hormones. Thyrotoxicosis refers to biochemical & physiological manifestations of excessive thyroid hormones Hyperthyroidism is one of the causes of thyrotoxicosis.

Clinical types of thyrotoxicosis :

1. Diffuse toxic goitre (Grave’s disease).
2. Toxic nodular goitre
3. Toxic nodule.
4. Hyperthyroidism due to rarer causes :

• Thyrotoxicosis factitia
• Autoimmune thyroiditis or de Quervain’s thyroiditis.
• Neonatal thyrotoxicosis.
• Struma ovarii.

Symptoms of hyperthyroidism / thyrotoxicosis :

Gastrointestinal system : 

• Increased appetite.
• Weight loss.
• Diarrhoea.

Cardiovascular system :

• Palpitations.
• Shortness of breath at rest or on minimal exertion.
• Angina

Neuromascular system : 

• Fatigue.
• Muscle weakness.
• Tremor.

Skeletal system : 

• Increase in linear growth in children.

Genitourinary system : 

• Oligomenorrhoea or amenorrhoea.
• Occasional urinary frequency.

Integument : 

• Hair loss.
• Gynaecomastia.
• Pruritus.
• Palmer erythema

Psychiatry : 

• Irritability.
• Nervousness.
• Insomnia.

Sympathetic overactivity : 

• Dyspnoea.
• Palpitations.
• Tiredness.
• Heat intolerance (recent preference for cold).
• Sweating
• Nervousness.
• Increased appetite.
• Weight loss.

Signs of hyperthyroidism : 

Eye signs : 

• Exophthalmos
• Lid retraction.
• Lid lag (von-Graefe’s sign).
• Stellwag’s sign.
• Joffroy’s sign.
• Moebius sign.
• Naffziger’s sign.
• Kocher’s sign.

Cardiovascular signs : 

• Tachycardia (As per Crile’s grading, sleeping pulse rate is usually checked for 3 consecutive nights & average is taken as the value).
• Extra-systoles.
• Atrial fibrillation.

Myopathy : 

• Weakness of proximal muscles.

Investigations of hyperthyroidism :

1. Thyroid function tests: High T, & T, and low TSH levels.
2. Radioisotope study by
3. Antithyroid antibodies.
4. X-ray neck lateral and A/P view.
5. Serum Ca++ level.
6. Indirect laryngoscopy.
7. FNAC.
8. X-ray chest.
9. Ultrasonogram.
10. ECG – To see cardiac abnormality (e.g. atrial fibrillation).

Treatment of hyperthyroidism : 

(Principles of treatment);

Non-specific measures:

• Rest.
• Sedation.

Medical treatment :

  Relief of symptoms:

• Beta blockers: Propranolol, nadolol, metaprolol.
• Calcium channel blockers: Verapamil & diltiazem.
• Oral rehydration.

Antithyroid drugs:  [< 45 years, small size- child & young patient (not much swelling)

Release of hormones: Lugol’s iodine (potassium iodine & iodide) 10 drops 3 times day.

Production of thyroxine:

• Carbimazole : 10 mg 3-4 times per day for 8-12 weeks. When the patient becomes biochemically euthyroid, maintenance dose is 5 mg 2 to 3 times daily for 6-24 months.
• Methimazole (long acting): 20-40 mg once daily (Contraindicated in pregnancy).
• Propylthyouracil: 100 mg three times daily. (Can be used in pregnancy).

Action on thyroxine on end organs: Propranolol 40 mg three times daily.

Production of antibodies: Steroids, Methimazole, Carbimazole.

Surgery :  [<45 years, in diffuse toxic Goitre, toxic nodular Goitre, recurrence, cosmetic] Subtotal thyroidectomy.

Radioiodine :  Age> 45 years, recurrence after surgery.

Indications of surgery in thyrotoxicosis :

1. Failure of drug treatment in primary thyrotoxicosis in young patient.
2. Age 45 years.
3. Diffuse toxic Goitre.
4. Toxic nodular Goitre with overactive internodular tissue.
5. When malignancy cannot be ruled out.
6. Grave’s disease in children, Grave’s with nodules.
7. Need for Antithyroid drugs for more than 2 years.
8. Large goitre, Substernal / Intrathoracic goitre.
9. Pressure symptoms.
10. Recurrent Goitre.
11. For cosmetic purpose.

Pre-operative preparation of a thyrotoxicosis patient :

• The aim is to make the patient euthyroid or near euthyroid at operation.
• Preparation is as an outpatient and only rarely admission to hospital is necessary.
• Carbimazole 30-40 mg a day is the drug of choice for preparation taken in divided doses at 6-8 hourly intervals.
• When euthyroid- after 8-12 weeks- the dose may be reduced to 5mg 8 hourly and the addition of thyroxine may facilitate maintenance of the euthyroid state.
• The last dose of carbimazole may be given on the evening before surgery.
• lodides may be given with carbimazole for 10-14 days immediately before operation but their use is of doubtful value and has been given up in many centers.
• An alterative method of preparation that appears to be safe is to abolish the clinical manifestations of the toxic state using beta-blocking drugs.
• Propranolol 40mg 3 times daily or Nadolol 120mg once daily are appropriate.
• Clinical response to beta-blockers is rapid. If patient becomes clinically euthyroid, an operations date may be arranged, if not, the dose of beta-blocker is increased with early reassessment.
• Beta-blockers act by inhibiting the peripheral conversion of T4 to T3. Hence, they act on the target organs and not on the gland itself.
• It is important to continue to give the drug for 7 days postoperatively.
• The addition of iodine for 10 days before operation gives additional measure of safety in case the early morning dose of beta-blocker on the day of operation is mistakenly omitted.

Pre-operative investigations :

• Thyroid function tests.
• Indirect laryngoscopy- for symptomless cord paralysis.
• Thyroid antibodies.
• Serum Ca++ estimation.
• Isotopes scan in patients with toxic nodular goitre.