Thyroid disorders

Diseases of the thyroid predominantly affect females and are common, occurring in about 5% of the population

The thyroid axis is involved in the regulation of cellular differentiation & metabolism in virtually all nucleated cells, so that disorders of thyroid function have diverse manifestations

Structural diseases of the thyroid gland, such as goitre, commonly occur in patients with normal thyroid function

What is the advantage of free hormone measurement? How do you explain that the TSH is usually regarded as the most useful investigation of thyroid function? In which situation the interpretation of TSH values without considering thyroid hormone levels may be misleading?

Modalities commonly employed in the investigation of thyroid disease T 3, T 4, TSH antibodies against the TSH receptor or other thyroid antigens radioisotope imaging fine needle aspiration biopsy ultrasound

Presenting problems in thyroid disease The most common presentations are: Hyperthyroidism (thyrotoxicosis), hypothyroidism enlargement of the thyroid (goitre)

Thyrotoxicosis It describes a constellation of clinical features arising from elevated circulating levels of thyroid hormone The most common causes are: 1. Graves’ disease 2. Multinodular goitre 3. Toxic adenoma 4. Thyroiditis

What are the most common signs & symptom of hyperthyroidism? How do you interpret thyroid function tests results? What are the extra thyroidal source of thyroid hormone? How do you explain the diverse effect of Iodine on thyroid function? How do you explain that all causes of thyrotoxicosis cause lid retraction and lid lag? What are the features that are unique for grave's diseases?

Investigations That confirm the diagnosis by T 4, T 3, TSH. That determine the underlying cause, including measurement of: a. TSH receptor antibodies (TRAb, elevated in Graves’ disease b. Isotope scanning Other non-specific abnormalities are common That show the complications e.g. ECG 1. What are the advantages of 99m technetium scintigraphy scans over radio-iodine uptake tests? 2. What are the results of consuming excessive amounts of a thyroid hormone 3. What are the non-specific laboratory abnormalities in thyroid dysfunction?

Management Definitive treatment of thyrotoxicosis depends on the underlying cause and may include: anti thyroid drugs radioactive iodine Surgery What do you advise the thyrotoxic patient who will take anti thyroid drugs?

Thyrotoxic crisis (‘thyroid storm’) rare & life-threatening The most prominent signs are: fever, agitation, confusion, tachycardia or atrial fibrillation and, in the older patient, cardiac failure. Thyrotoxic crisis is most commonly precipitated by: infection, shortly after subtotal thyroidectomy, within a few days of radioactive iodine therapy How do you manageThyrotoxic crisis ? p.p. 741 How do you treat thyrotoxicosis during pregnancy? p.p. 745–747

By using clinical features, investigations, treatment, prognosis, compare among; graves disease, thyroiditis multinodular goiter, toxic adenoma

Hypothyroidism Hypothyroidism is common autoimmune disease (Hashimoto’s thyroiditis) and thyroid failure following 131 I or surgical treatment of thyrotoxicosis account for over 90% of cases, except in areas where iodine deficiency is endemic. Women are affected approximately six times more frequently than men.

Clinical assessment The clinical presentation depends on the duration and severity of the hypothyroidism. Most cases of hypothyroidism are not clinically obvious Care must be taken to identify patients with transient hypothyroidism, in whom life-long thyroxine therapy is inappropriate How do you explain a low-pitched voice, poor hearing, slurred speech, carpal tunnel syndrome, non-pitting oedema (myxoedema) in hypothyroid patients? p.p. 741 What are the clinical features that make the diagnosis of hypothyroidism is simple? p.p. 741

Management By thyroxine, which should be adjusted to maintain serum TSH within the reference range. How do you interpret ↑ T 4 & ↑TSH? Write briefly about thyroxine replacement in ischemic heart disease. How do you treat pregnant women with hypothyroidism? Why do you treat such a patient? What are the ECG changes in hypothyroidism? Why do we not measure T3 in a hypothyroidism?

Myxoedema coma It is a rare presentation of hypothyroidism in which there is: a depressed level of consciousness Body temperature may be as low as 25°C convulsions are not uncommon cerebrospinal fluid (CSF) pressure and protein content are raised. The mortality rate is 50% survival depends upon: early recognition and treatment of hypothyroidism and other factors contributing to the altered consciousness level, such as phenothiazine's,cardiac failure, pneumonia, dilutional hyponatremia, respiratory failure

How do you treat Myxoedema coma? Write briefly regarding each of the following: a. subclinical hyperthyroidism b. subclinical hyperthyroidism c. Non-thyroidal illness (‘sick euthyroidism’)