4. Pathology of the thyroid and parathyroid glands Flashcards
Clinical presentation of an abnormal thyroid?
Goitre (due to swollen gland, does not diagnose)
Lump (could be part of goitre, neoplasma etc i.e. doesn’t diagnose)
Hypothyr
Hyperthyr
What decides if a goitre is toxic or non-toxic?
Production of thyroxine, is it excessive?
Non-toxic goiter:
-A simple enlargement of the thyroid gland without any increased secretion of thyroid hormone
-TSH levels rise in an attempt to enhance the production of thyroid hormones (T3 & T4)
-Symptom-less usually
Toxic goiter:
- Mainly occurs as a result of a hypersensitivity reaction to an IgG auto-antibody that acts on surface receptors for TSH on thyroid epithelium.
- In these patients, a remarkable rise occurs in both T3 and T4 concentrations. The increase in thyroid hormone levels results in reduced TSH release
Type of goitre?
Causes?
Pathogenesis?
1. Euthyroid: • Diffuse – younger people • Multinodular – older 2. Hypothyroid • Iodine deficiency - endemic or seaweed↑
Goitre, causes?
– Drugs–lithium,amiodarone
– Diet–cabbage,turnips
Pathogenesis
• Reactive
• Iodine block
• Genetic
Solitary thyroid nodule
• Who gets it? Middle adulthood, female
Confirm it’s not goitre
If it’s not goitre, then assume cancer until proven otherwise
S/S of benign vs malignant masses in solitary thyroid nodule
Benign masses are usually movable, soft, and non tender.
Malignancy is associated with a hard nodule, fixation to surrounding tissue, and regional lymphadenopathy.
Hard: They illicit fibrous stromal response
Hypothyroidism, S/S?
Muscle weakness Coarse, brittle hair Loss of lateral eyebrows Pallor Periorbital oedema and puffy face Large tongue Voice hoarseness Constipation Menorrhagia Peripheral oedema
Why is it important to rapidly investigate local nerve involvement?
May be indicative of local invasiveness from malignancy. The most important of these signs are dysphagia and hoarseness.
What 4 tests are used in solitary thyroid diagnosis?
- Thyroid function tests - An elevated thyroid-stimulating hormone (TSH) level may indicate thyroiditis; a very low TSH level indicates an autonomous or hyperfunctioning nodule
- Antithyroid antibodies - Helpful in diagnosing chronic lymphocytic thyroiditis (Hashimoto thyroiditis)
- Complete blood count (CBC) –Abscess
- Fine needle aspirate: Doesn’t show you whole picture
What imaging studies are used in solitary thyroid diagnosis?
- Ultrasonography - To determine whether the nodule is cystic, solid, or mixed
- Radioiodine scintigraphy - To determine whether the nodule is cold, warm, or hot.
- Chest radiography - If malignancy is suspected, given the high incidence of early metastases to the lungs
- Computed tomography (CT) scanning and magnetic resonance imaging (MRI) - To analyze the extent of disease by scanning the neck and chest
Hyperthyroidism:
Causes?
Commonest is Graves – may present as diffuse toxic goitre. Presents as hypersensitivity
- Functional goitre
- Toxic adenoma
Hypothyroidism causes?
Congenital or Autoimmune – Defective TH production – Loss of parenchyma – Deficient TSH
Hyperthyroidism S/S
muscle wasting Fine hair Exophthalmos Goiter Sweating Tachycardia Weight loss Oligomenorrhea Tremor
Hypothyroidism causes?
Congenital or Autoimmune – Defective TH production – Loss of parenchyma – Deficient TSH
Cause and epidemiology of Grave’s?
Cause:
Autoimmune, antibodies pressing ON switch for proliferation and hyperfunction.
Immune – IgG against TSH receptor on thyrocytes
Less than 40yrs
Females
Family history:
HLA DR3 and CTLA-4
Chronic autoimmune – Hashimoto thyroiditis Gender? Presentation? Cause? FH?
Females 30-50y
Present as hyper- or hypo- thyroidism
Causes:
•Autoreactive CD8 T lymphocytes
•Autoreactive antibodies: thyroid microsomal in almost all 95% thyroglobulin in two thirds, minority have blocking TSH receptor antibodies
•Other causal risks? Increased iodine intake, viral infection
FH:
•Family history strong and other autoimmune diseases
Risk: Lymphoma development
