CPC on Thyroid and Parathyroid Glands
Introduction
Diseases of the thyroid gland constitute a major component of endocrine and surgical practice due to their wide-ranging systemic effects and diverse clinical presentations. The thyroid gland plays a critical role in regulating metabolism, growth, development, and cardiovascular function through the secretion of thyroid hormones. Disorders of the thyroid may present as functional abnormalities, structural enlargement, nodularity, inflammatory conditions, or neoplastic diseases, often posing diagnostic and therapeutic challenges.
This presentation comprehensively reviews the embryology, anatomy, physiology, and pathology of the thyroid gland, with emphasis on common thyroid disorders including goitre, hypothyroidism, thyrotoxicosis, thyroiditis, and thyroid malignancies. The discussion also highlights modern diagnostic approaches, interpretation of thyroid function tests, imaging modalities, and principles of medical and surgical management, aiming to provide a clear clinical framework for evaluation and treatment of thyroid diseases.
Key Points
Embryology and Anatomy
The thyroid gland originates from the primitive foregut and descends along the thyroglossal tract.
Developmental anomalies may result in ectopic thyroid tissue or thyroglossal cysts and fistulae.
Anatomically, the gland consists of two lobes connected by an isthmus, with rich vascular and lymphatic supply, making surgical intervention technically demanding.
2. Physiology of Thyroid Hormones
The principal thyroid hormones are Tri-iodothyronine (T3) and Thyroxine (T4).
These hormones regulate:
Basal metabolic rate
Lipid and carbohydrate metabolism
Growth and neurological development
Hormone synthesis depends on adequate iodine intake and proper enzymatic activity within thyroid follicles.
3. Thyroid Function Tests and Diagnostics
Serum TSH remains the most sensitive initial screening test for thyroid dysfunction.
Measurement of total and free T3 and T4 helps assess biologically active hormone levels.
Thyroid autoantibodies (anti-TPO, anti-thyroglobulin, TSI) assist in diagnosing autoimmune thyroid disorders.
Imaging modalities include:
Ultrasound of the neck
Radionuclide thyroid scanning (I¹²³, I¹³¹, Tc-99m)
CT, MRI, and PET scans in selected cases
4. Goitre and Thyroid Nodularity
Goitre may be diffuse or nodular, toxic or non-toxic, benign or malignant.
Solitary and dominant nodules carry varying risks of malignancy, higher in:
Solid nodules
Male patients
Cold nodules on radionuclide scan
Fine Needle Aspiration Cytology (FNAC) plays a crucial role in evaluation.
5. Hypothyroidism
Characterized by reduced thyroid hormone levels.
Common features include:
Weight gain
Cold intolerance
Bradycardia
Dry skin and hair
Menstrual irregularities
Management primarily involves thyroxine replacement therapy.
6. Thyrotoxicosis and Graves’ Disease
Thyrotoxicosis results from excessive thyroid hormone production.
Graves’ disease is the most common cause, mediated by TSH receptor–stimulating antibodies.
Clinical features include:
Tachycardia
Weight loss
Heat intolerance
Tremors and ophthalmopathy
Management options include:
Antithyroid drugs
Beta blockers
Radioactive iodine
Surgical thyroidectomy
7. Thyroiditis
Includes:
Chronic lymphocytic (Hashimoto’s) thyroiditis
Subacute granulomatous (De Quervain’s) thyroiditis
Riedel’s thyroiditis
Autoimmune thyroiditis is strongly associated with hypothyroidism and increased risk of lymphoma.
Treatment varies from conservative management to steroids or surgery depending on the type.
8. Surgical Management and Complications
Indications for surgery include:
Large goitres
Malignancy
Failed medical therapy
Compressive symptoms
Potential postoperative complications include:
Hemorrhage
Recurrent laryngeal nerve injury
Hypocalcemia
Thyroid storm
