Toxic goiters and Thyrotoxicosis
A goiter refers to an enlarged thyroid gland. Sometimes, a person can have a goiter that has multiple nodules or bumps on it, which is called a multinodular goiter. A toxic goiter is one that makes too much thyroid hormone, resulting in a condition called hyperthyroidism.
Thyrotoxicosis – is a condition in which there is increased metabolic rate due to high level of circulating thyroid hormone. It is about eight times more commonly seen in females than males.
The most significant symptoms are
- Loss of weight in spite of good appetite,
- A recent preference of cold
- Emotional liability.
The most important clinical signs of thyrotoxicosis commonly seen are
- excitability of the patient,
- the presence of goiter,
- hot and moist palms,
- exophthalmus in primary type
- tachycardia with cardiac arrhythmia
- Weakness of the proximal limb muscles
- The goiter in primary thyrotoxicosis (Grave’s disease) is diffuse and vascular, it may be large or small, firm or soft and bruit may be present. Whereas in secondary thyrotoxicosis the goiter is nodular
Diffuse toxic goiter: Primary toxic goiter or Grave’s disease is a diffuse vascular goiter appearing at the same time as symptoms of hyperthyroidism. It usually occurs in younger women and frequently associated with eye signs. The hypertrophy and hyperplasia are due to abnormal thyroid stimulating antibodies.
Toxic nodular goiter: Toxic nodular goiter involves an enlarged thyroid gland that contains a small rounded mass or masses called nodules, which produce too much thyroid hormone. A simple nodular goiter is present for a long time before the hyperthyroidism, and hence termed secondary thyrotoxicosis. It is usually seen in middle aged or elderly people and less frequently associated with eye signs. In many cases of toxic nodular goiter, the nodules are inactive and it is the intermediate thyroid tissue that is involved in hyper secretion.
Alternative Names:Toxic adenoma; Toxic multinodular goiter; Plummer’s disease
Symptoms of toxic nodular goiter
- weight loss
- increased appetite
- heat intolerance
- increased sweating
- muscle cramps
- frequent bowel movements
- menstrual irregularities (in women)
Signs and tests:
- A physical examination reveals single or multiple nodules in the thyroid. There may be a rapid heart rate.
- A thyroid scan shows elevated radioactive iodine uptake in the nodules.
- Serum TSH (thyroid stimulating hormone) is decreased.
- Serum thyroid hormone levels (T3, T4) are elevated.
Toxic nodule: This is a solitary hyperactive nodule which may be part of a generalized nodularity or a true toxic adenoma. It is autonomous and its hypertrophy and hyperplasia are not due to thyroid stimulating antibodies. Because TSH secretion is suppressed by the high level of circulating thyroid hormones, the normal thyroid tissue surrounding the nodule is suppressed and inactive.
Diagnosis of thyrotoxicosis
- Most cases are easily diagnosed by the clinical picture.
- The thyroid functional status can be determined by estimation of serum thyroxin hormones and TSH.
- Isotope scanning is used to investigate discrete thyroid swelling. This helps to determine the functional activity relative to the surrounding gland according to isotope uptake.
Anti thyroid Drugs: Antithyroid drugs are used to resume the patient to a euthyroid state and to maintain this for a prolonged period. But it should be clear that antithyroid drugs cannot cure a toxic nodule since the overactive thyroid tissue is autonomous and recurrence of the hyperthyroidism is certain when the drug is discontinued.
Surgery: Surgery cures thyrotoxicosis by reducing the mass of overactive tissue below critical mass. Preoperatively, the patient must be prepared with antithyroid drugs so that the patient becomes euthyroid. The preferred procedure is subtotal thyroidectomy.
- Hemorrhage – a tension hematoma may develop deep to the cervical fascia – which is potentially life threatening
- Respiratory obstruction – can occur due to laryngeal edema or secondary to tension hematoma.
- Recurrent laryngeal nerve paralysis may be unilateral or bilateral and could be transient or permanent.
- Thyroid insufficiency. This is insidious and usually occurs after 2 years.
- Parathyroid insufficiency – is due to removal of parathyroid gland and usually seen in immediate post operative period.
- Thyrotoxic crisis (storm) – is an acute exacerbation of hyperthyroidism. It occurs if a thyrotoxic patient has been inadequately prepared for thyroidectomy.
- Wound infection – a subcutaneous or deep cervical abscess may occur rarely and necessitates drainage.