Thyroid Conditions, Signs, Causes And Differentials Flashcards
Why does post-partum thyroiditis present as hyperthyroidism initially and then switch to hypothyroidism?
As the gland is destroyed it releases its thyroxine stores, this causes the hyperthyroidism.
Once the stores are depleted and the gland damaged, the ability to make thyroxine is reduced, so the patient becomes hypothyroid.
This is all usually transient and doesn’t often require treatment.
What are the signs of hyperthyroidism?
Mood swings: agitation, hyperactivity, insomnia, irritability, anxiety Increased appetite Heat intolerance Eye lid retraction Atrial fibrillation (irregular pulse) Tachycardia Palpitations HTN Weight loss Oncholysis Palmar erythema Tremor Warm, moist skin Polyuria, polydipsia Diffuse pruritis Reduced libido and gynaecomastia Infertility (reduced periods and sperm count) Oligomenorrhoea or amenorrhoea Frequent bowel action Hyperreflexia Osteoporosis
What are the signs of Graves’ disease?
Signs specific to Graves’ disease:
Exophthalmos
Chemosis (oedema of the conjunctiva, eyes look gelatinous)
Periorbital oedema
Opthalmoplegia
Thyroidacropachy (finger clubbing and soft tissue swelling)
Pretibial myxoedema (non-pitting swelling and lumpiness with orange peel appearance)
General hyperthyroidism signs:
Mood swings and agitation Increased appetite Heat intolerance Eye lid retraction Goitre Atrial fibrillation (irregular pulse) Tachycardia Palpitations HTN Weight loss Oncholysis Tremor Warm, moist skin Osteoporosis
What are the differentials for a lump palpated in the throat?
(Think of the objects of the neck that are superficial enough for palpation, think of the types of tissue present)
Goitre: Toxic/Non-toxic multinodular, Graves’ disease, Hashimoto’s thyroiditis, solitary toxic nodule (unilateral)
Enlarged parathyroid gland
Parathyroid carcinoma
Metastasis
Colloid nodule
Toxic/non-toxic Thyroid adenoma (adenomas are glandular, therefore can be secretory)
Thyroid cancer: papillary/follicular/anaplastic/medullary carcinoma
Thyroglossal duct cyst
Lymphoma
Enlarged lymph node (infection)
What are the signs of hypothyroidism?
Four of the signs are cardinal
Most important signs for distinguishing hypothyroid from euthyroid:
Cold intolerance
Constipation (lower basal metabolic rate)
Myalgia and muscle weakness (no T4 anabolic drive)
Hoarse/deep voice
Other signs:
Weight gain
Severe fatigue
Bradycardia
Cool, dry skin
Dry brittle hair/hair loss
Delayed relaxation of tendon reflexes
Menorrhagia and resultant anemia
Difficulty conceiving
What is Hashimoto’s thyroiditis?
An autoimmune condition that is the most common cause of primary hypothyroidism.
MOA: T cells infiltrate the thyroid gland and cause inflammation, which precedes tissue destruction.
Initially this releases thyroxine stores and causes hyperthyroidism signs, then depletion occurs and causes hypothyroidism.
What are the causes of primary hypothyroidism?
- Autoimmune t-cell infiltration (Hashimoto’s thyroiditis)
- Lithium (Treatment: bipolar disorder, mania, recurrent depression)
- Amiodarone (Treatment: arrhythmias)
- Neck irradiation
- Thyroidectomy
- Congenital dysgenesis of thyroid gland
- Interferon (Treatment: Hepatitis B/C, MS, lymphoma, leukaemia)
- Iodine deficiency
- Hyperthyroidism drugs: carbimazole and propylthiouracil
- Rifampicin
- Thalidomide
What are the causes of primary hyperthyroidism?
- Autoimmune stimulation of the TSH receptor - Graves’ disease
- Toxic multinodular goitre (uncertain pathogenesis - treat as its own condition causing hyperthyroidism)
- Solitary benign adenoma of the thyroid gland (solitary toxic nodule)
- Interferon (Treatment: Hepatitis B/C, MS, lymphoma, leukaemia)
- Amiodarone (Treatment: arrhythmias)
- Lithium (Treatment: bipolar disorder, mania, recurrent depression)
What are the causes of secondary hypothyroidism?
Numerous causes exist.
- Pituitary mass lesions: adenomas (most common), tumours, cysts, meningiomas, metastases and other
- Infectious Infiltration of hypothalamus/pituitary: TB, syphilis, toxoplasmosis)
- Non-infectious Infiltration of hypothalamus/pituitary: Sarcoidosis, haemachromatosis
- Head trauma
- Stroke (in pituitary blood supply)
- Pituitary infarct (Sheehans syndrome, e.g. post-part I’m haemorrhage)
- Pituitary/hypothalamus surgery
- Bexarotene
What are the causes of secondary hyperthyroidism?
- Post-partum thyroiditis (initially hyperthyroid and then hypothyroid, unknown pathogenesis)
- Secreting pituitary adenoma
- High levels of human chorionic gonadotrophin (first trimester of pregnancy)
What are the types of goitre?
Graves’ disease - diffuse enlargement with bruit
Toxic multinodular goitre - non-tender, multiple nodules
Solitary toxic nodule (adenoma) - non-tender, unilateral
Colloid goitre (euthyroid)
Amiodarone goitre - small
When should you suspect post-partum thyroiditis?
TSH is raised within one year of giving birth.
Patient will be showing signs of hyperthyroidism (early stages) or hypothyroidism (later stages)
What are the signs of myxoedema (hypothyroid) coma?
Bradycardia
Hypotension
Hypoglycaemia
Decreased mental status
Hypothermia
Unconsciousness
All the features of normal hypothyroidism
What is the most common reason for a patient presenting with hyperthyroidism?
Graves’ disease (80% of presentations)
Multinodular goitre is second most common - 5-15%
What is the most common type of thyroid cancer?
Papillary carcinoma (70% of all thyroid cancers)
Follicular carcinoma is the second most common (20%)
Both originate from the follicular epithelium.
What is papillary carcinoma?
A slow-growing (indolent) cancer of the follicular epithelium of the thyroid.
It’s a polyfocal cancer with multiple neoplasms, and may form cysts too.
Metastasises to local lymph nodes.
Good prognosis.
What is a toxic multinodular goitre?
Two or more autonomously functioning nodules that old hormones.
The second commonest cause of hyperthyroidism.
Pituitary infarction (sheehans syndrome) and postpartum thyroiditis - following postpartum haemorrhage, which of these will present with problems breast feeding, low free T4 and low TSH?
Pituitary infarction.
Postpartum thyroiditis is caused by autoimmune attack on the thyroid gland, it will not affect pituitary functions like prolactin production (breast milk stimulant)
Pituitary infarction will affect:
Prolactin - breast milk production
ACTH - cortisol production
FH and LSH - menses
What is thyroid orbitopathy?
Thyroid eye disease.
Due to antibody attack (Graves’ disease) on the orbit due to similar antigens being expressed there. This leads to T cell infiltration of the soft tissues and muscles.
This can lead to compression of the optic nerve and blindness.
Signs: Proptosis Chemosis (Conjunctival oedema and swelling) Periorbital swelling Opthalmoplegia Inflammation of the palpebra Blurred or double vision (due to opthalmoplegia) Photophobia
What are the risks to a foetus if hyperthyroidism isn’t treated during pregnancy?
Premature delivery
Intrauterine foetal growth restriction
