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.
