Clinical Thyroid Disease Flashcards
Symptoms / signs of hypothyroid?
- Weight Gain
- Lethargy
- Feeling cold
- Constipation
- Heavy periods
- Dry Skin/Hair
- Bradycardia
- Slow reflexes
- Goitre
- Severe – puffy face, large tongue, hoarseness, coma
What are the signs / symptoms of hyperthyroid?
- Weight Loss
- Anxiety/Irritability
- Heat Intolerance
- Bowel frequency
- Light periods
- Sweaty palms
- Palipitations
- Hyperreflexia/Tremors
- Goitre
- Thyroid eye symptoms/signs
How do TSH ans FT4/FT3 compare for primary, subclinical and secondary hypothyroidism?
Primary relates to pathology associated with the thyroid gland
Has raised TSH, low FT4 and FT3
Subclinical (compensated):
Normal TSH, normal FT4 and FT3
Secondary (pituitary)
Low TSH, Low FT4 and FT3
What are the congenital causes of hypothyroidism?
Developmental
(agenesis / maldevelopment)
Dyshormonogenesis
(trapping / organification / dehalogenase)
What are the causes of acquired primary hypothyroidism?
Acquired
- Autoimmune thyroid disease
(hashimotos / atrophic)
-Iatrogenic
(Post operative / post - radioactive iodine)
(external RT for head and neck cancers
(antithyroid drugs, amiodarone, lithium, interferon)
- Chronic iodine deficiency
Post - subacute thyroiditis
(post partum thyroiditis)
What are the casues of secondary / tertiary hypothyroidism?
•Pituitary / hypothalamic damage
–pituitary tumour eg tumour
–craniopharyngioma
–post pituitary surgery or radiotherapy
–Sheehan’s syndrome
–isolated TRH deficiency
What are the relevant investigations for hypothyroidism?
TSH / FT4
Autoantibodies: TPO (thyroid peroxidase antibodies)
Hypercholesterolaemia
Hyponatraemia (due to SIADH)
Increased muscle enzymes, ALT, CK
Hyperprolactinaemia
What is the treatment of hypothyroidism?
Levothyroxine (T4) tablets
Liothyronine (T3)
Combination of T3 and T4 confers no benefit according to studies
Increasing dose of levothyroxine until TSH levels are normal
After stabilisation - annual testing of TSH
When is the treatment of hypothyroidism different?
Ischaemic heart disease
(lower dose, increasing cautiously)
Pregnancy
(increase in LT4 dose, inadequately treated hypothyroidism is linked with increased foetal loss and lower IQ, subclinical hypothyroidism should be treated if planning pregnancy (or if they are pregnant))
Postpartum thyroiditis
(trial withdrawal and measure TFT’s in 6 weeks)
Myxedema coma
(Very rare emergency, may need IV T3 (steroid))
What is meant by subclinical hpothyroidism?
Subclinical hypothyroidism (SCH) is defined as a serum thyroid-stimulating hormone (TSH) level above the upper limit of normal despite normal levels of serum free thyroxine.
When do you treat subclinical hypothyroidism?
- Consider treatment TSH > 10
- TSH > 5 with positive thyroid antibodies
- TSH elevated with symptoms
–Trial of therapy for 3 to 4 months and continue if symptomatic improvement
What are the risks of over treatment of subclinical hypothyroidism?
Osteopenia and atrial fibrillation
What are the casues of goitre?
•Physiological
–Puberty
–Pregnancy
•Autoimmune
–Graves’ disease
–Hashimoto’s disease
•Thyroiditis
–Acute (de Quervain’s )
–Chronic fibrotic (Reidel’s)
- Iodine deficiency (endemic goitre)
- Dyshormogenesis
- Goitrogens
What are the types of goitre?
- Multinodular Goitre
- Diffuse goitre
–Colloid
–Simple
- Cysts
- Tumours
–Adenomas
–Carcinoma
–Lymphoma
•Miscellaneous
–Sarcoidosis, Tuberculosis
What causes a solitary nodule of the thyroid?
Previous head and neck irradiation
What is the risk assocaited with a solitary thyroid nodule?
Malignancy (5%)
What are the symptoms associated with a solitary nodule of the thyroid?
Pain
Cervical lymphadenopathy
What are the investigations for solitary thyroid nodule investigations?
Thyroid function test - (testing for a solitary toxic nodule)
Isotope scanning if low TSH: hot nodule
Ultrasound: Useful in differentiating benign vs malignant
FNA
Chest and thoracic inlet X-rays if large retrosternal extensions
What is meant by a hot nodule?
A hot nodule is defined as a nodular region of the thyroid gland that takes up large amounts of radioactive iodine relative to the rest of the thyroid gland, hence it is visualized as a “hot spot” on the thyroid scan.
What is meant by a cold nodule?
If a nodule is composed of cells that do not make thyroid hormone (don’t absorb iodine), then it will appear “cold” on the x-ray film. A nodule that is producing too much hormone will show up darker and is called “hot.” 85% of thyroid nodules arecold, 10% are warm, and 5% are hot
What are the types of thyroid cancer?
Papillary:
–Commonest
–Multifocal, local spread to lymph nodes
–Good prognosis
Follicular:
–Usually single lesion
–Metastases to lung/bone
–Good prognosis if resectable
When is there poor prognosis of thyroid cancer?
If the patient is younger than 16 or older than 45
Large tumour size
If there is spread outside thyroid capsule and metastases
What is the treatment for thyroid cancer?
Near total thyroidectomy
High dose radioiodine (ablative)
Long term suppressive doses of thyroxine
Follow - up:
Thyroglobulin
WHole body iodine scanning (after 2-4 weeks of thyroxine withdrawal)
What are other forms of thyroid cancer apart from papillary and follicular?
Anaplastic
Lymphoma
Medullary
What are the facts about anaplastic thyroid cancer?
Rare
Aggressive, locally invasive
Very poor prognosis
Does not respond to radioiodine, external radiotherapy may help briefly
What are the facts about lymphoma?
Rare; may arise from preexisting hashimotos thyroiditis
External RT more helpful, combined with chemotherapy
What type of cells does medullary thyroid cancer arise from?
Parafollicular C cells
What is medullary thyroid cancer often associated with?
MEN2
(phaeochromocytoma and hyperparathyroidism)
What are the findings of the blood when there is a medullary thyroid cancer present?
Raised serum calcitonin
What is the treatment for medullary thyroid cancer?
Total thyroidectomy
No role for radioiodine
What are the causes of thyrotoxicosis?
•Primary
–Grave’s disease (70%)
–Toxic Multinodular Goitre (20%)
–Toxic adenoma
•Secondary
–Pituitary adenoma secreting TSH
•Thyrotoxicosis without hyperthyroidism
–Destructive thyroiditis (post-partum, subacute [de Quervain’s], amiodarone-induced
–Excessive thyroxine administration
What are the factors that drive the autoimmune portion of Grave’s disease?
•Autoimmune driven condition
–thyroid peroxidase Antibodies
–TSH receptor Antibodies
–review personal/family history for concurrent autoimmune disease
Define thyrotoxicosis
Another term for hyperthyroidism
What is the most common cause of thyrotoxicosis in the elderly?
Multi-nodular goitre
Characteristic goitre and the absence of grave’s disease
Will not go into spontaneous remission
What is subacute thyroiditis?
Also called de quervain’s thyroiditis
Viral trigger of thyroiditis
(enteroviruses, coxsackie)
Features thyrotoxicosis for about 3-6 weeks. followed by hypothyroidism for 3-6 months
What are the symptoms for subacute thyroiditis?
Painful goitre
Maybe fever/myalgia/
raised ESR
(erythrocyte sedimentation rate)
What is potential treatment for subacute thyroiditis?
Short-term steroids and NSAIDs
What is the management for thyrotoxicosis?
Antithyroid drugs
Radioactive Iodine
Surgery
What are the antithyroid drugs?
Carbimazole
Propylthiouracil
Can be administered in one of two ways - titration regimen or block and replace
Block and replace involves blocking with the antithyroid drug and then replacing with thyroxine
What is the risk associated with radioiodine?
Hypothyroidism
After receiving radioiodine - you are not meant to come into contact with children or pregnant woman because you probably have radioiodine in the neck
When is radioiodine usually avoided?
Severe eye disease
What are the hormone features of subclinical hyperthyroidism?
TSH suppressed
Normal free thyroid hormones
What are the main concerns associated with subclinical hyperthyroidism?
Decreased bone density in post menopausal
AF: 3 fold risk in over 60’s
When is treatment considered in hyperthyroidism?
•Treatment considered ATD/RAI if persistent especially in elderly or those with increased cardiac risk
