Lecture 8 Flashcards
Anna Crown: Thyroid Diseas: Hyper-, Hypo-, and Other
What is the difference between primary and secondary hypothyroidism?
Primary = due to a thyroid problem (end organ)
Secondary = due to a hypothalamic/pituitary problem
Define thyrotoxicosis
Overproduction of thyroid hormone (synonymous with hyperthyroidism)
What is euthyroid?
Normal production of thyroid hormone
What is a goitre?
non-specific term, means enlargement of thyroid gland. Patients may be hyperthyroid, euthyroid, or hypothyroid.
How far down does the thyroid extend and how can you examine it?
Beyond the sternum (retrosternal). Above the sternum can be palpated. Below, cannot be palpated but can be precussed.
Name a clinical finding resulting from goitre
tracheal deviation
What is TRH and why can’t you measure it?
Thyroid Releasing Hormone, promotes the release of Thyroid Stimulating Hormone (TSH), not enough in the blood to measure
Why is TSH the “best” biomarker to measure for thyroid status and what does it assume? What are its drawbacks?
Assumes normal pituitary function, best because reflects what pituitary regards as normal. Drawbacks: slow to respond to change (~6 wks), long tail (large normal range)
Are high thyroid autoantibodies a marker of autoimmune disease?
No, autoAB> autoimmune disease. But useful as a marker of risk.
Name 5 symptoms of hypothyroidism.
MAY BE NONE, lethargy, mild weight gain, cold intolerance, constipation, face puffiness, dry skin, hair loss, hoarseness, heavy menstrual periods
What do negative and positive autoAB results tell you about autommune disease?
Negative results do no exclude it, but positive result does confirm it.
Name 2 different types of thyroid autoantibodies.
Destructive (target thyroid for autoimmune destruction) and Stimulatory (stimulate TSH receptor)
What is a problem with thyroid symptoms?
Non-specific, many are common even in patients without thyroid disease
What is the difference between signs and symptoms?
Signs are found by the clinician on examination, symptoms are reportable by the patient.
Name 5 signs of SEVERE hypothyroidism.
Change in appearance (eg face), puffy and pale, periorbital oedema, dry flaking skin, diffuse hair loss, bradycardia, signs of median nerve compression (carpal tunnel), effusions (eg ascites, pericardial), delayed relaxation of reflexes, croaky voice, goitre, stupor or coma (rare)
When do you typically see severe hypothyroidism?
In patients who need to take replacement hormone medication that they don’t take.
What causes primary hypothyroidism?
Generally low T3 and T4, High TSH in attempt to stimulate thyroid hormone production. Most common autoimmune, tx after hyperthyroidism, thyroiditis, drugs, congenital causes, Iodine deficiency (not common in UK)
What indicates whether patients have primary or secondary hypothyroidism?
Both will have low T4 and T3, but secondary hypothyroidism will also have low TSH because the pituitary is not trying to stimulate hormone production.
What is your aim in treating hypothyroidism?
Bring T4 levels up without bringing down TSH (be careful not to overtreat)
How do you treat hypothyroidism?
Start with thyroxine (T4) 100 micrograms daily (usual dose 100-150, some variation with weight). No evidence supporting T3/T4 combo therapy
What is chronic autoimmune thyroiditis?
Autoimmune Hypothyroidism. Inflammed thyroid from being attacked by antibodies. Called Hashimoto’s disease if with goitre or lymphocytic infiltration.
What is myxoedema (coma)?
accumulation of glycosaminoglycans in institial space of tissues, can occur from very severe hypothyroidism