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
What is thyrotoxicosis?
Hyperhtyroidism
Name 5 symptoms of thyrotoxicosis.
Weight loss (despite increased apetite, rarely weight gain), lack of energy, heat intolerance, anxiety/irratibility, thirst, palpitations, pruritus, weight gain, loose bowels, oligomenorrhea
Name 5 signs of thyrotoxicosis.
Tremor, warm moist skin, tachycardia, brisk reflexes, eye signs, thyroid bruit, muscle weakness, atrial fibrillation
What are considered mild symptoms of thyroid eye disease (TED)/thyroid associated ophthalmopathy (TAO)?
Itchy/dry eyes and “prominent” eyes (proptosis)
When are symptoms of thyroid eye disease (TED)/thyroid associated ophthalmopathy (TAO) considered worrisome?
Diplopia/loss of sight, loss of coloured vision, redness/swelling of conjunctiva, unable to fully close eyes, ache/pain/tightness behind eyes
What are known associations for Thyroid Eye disease (TED)/thyroid associated ophthalmopathy (TAO)?
Autoimmune hyperthyroidism (Graves disease) in ~20% of patients, Increased risk in smokers, autoantibody mediated, inflammation of all orbital tissues except eye itself (fat, muscle, conjunctiva, eyelids), CT scan helpful
Name 4 areas to check and at least 2 signs found in each when considering thyrotoxicosis.
Hands (warm, fine tremor), Pulse (tachycardia, Atrial fibrillation), Neck (goitre, move when swallow, smooth/not, bruit/not), Eyes (lid retraction/lag, proptosis/exopthalmos, opthalmoplegia– abnormal eye movements, causes diplopia, Inflammation of conjunctiva)
What is the most common cause of hyperthyroidism?
Graves Disease/autoimmune hyperhtyroidism, responsible for 75% of cases (typically women 30-50 years)
Describe Graves Disease
Autoantibody stimulates the TSH receptor, causing excess hormone production and thyroid growth (goitre)
What kind of imaging is useful thyrotoxicosis?
Imaging using radioisotope markers to enhance the scan or ultrasound
Name 5 causes of thyrotoxicosis.
Graves disease, toxic multinodular goitre, toxic adenoma, thyroiditis, drug action
What causes gestational thyrotoxicosis and what is the expected outcome?
Beta-human chorionic gonadotrophin is structurally similar to TSH and has similar action on the thyroid. Settles after 1st trimester.
What are helpful diagnostic features in hyperthyroidism?
Likely Graves: Personal/family history of autoimmune disease, goitre with a bruit, thyroid eye disease, positive thyroid antibody titre
What options exist for treating hyperthyroidism?
Medical, Surgical, Radioiodine, Symptom control (beta-blockers), No treatment (symptoms may worsen: Atrial fibrillation or stroke, osteoporosis or fractures)
What medical therapies exist for hyperthyroidism?
carbimazole or propylthiouracil (PTU), 18 mo- 2 yr, titrate or block-replace.
When do you have to watch for when medically treating hyperhtyroidism and what do you do when suspected?
Rare side effect: agranulocytosis, stop drug, CBC
How many patients are cured of hyperthyroidism with medical tx?
1/3 longterm, 2/3 relapse usually first year, cannot predict in advance
What must you do before surgery or radiation for hyperthyroidism?
Medical tx until euthyroid
What lifestyle factors must be considered before radiation tx?
Not if pregnant/breastfeeding, avoid prolonged closed contact with others for 1-2 weeks post tx, wait 6 mo women/4 mo men for future pregnancies, airport security
When are radiation and surgery contraindicated for hyperthyroidism?
Not if severe thyroid disease, likely need thyroxine after tx,
What risks are specific to surgery for hyperthyroidism?
Visible scar, anaesthesia, hypoparathyroidism, vocal cord palsy (recurrent laryngeal nerve damage), hypothyroidism
What patient expectations should be managed before initiating tx?
Mood swings (emotion, panic, anxiety, irratibility), may be few months of lag to feeling normal (metabolic rollercoaster), thyroid tx does not help eye disease, weight gain risk, family plans
What is a thyroid crisis and who gets it?
Thyrotoxic crisis. Usually 2nd degree graves, incompletely treated (start-stop, erratic compliance, early in course of tx, surgery/radioiodine without prep), RARE
What are the features of a thyroid storm?
Multi System: Graves (goitre, TED), CNS (agitation, delirium), Cardiovascular (tachydardia .140bpm, Atrial dysrhythmias, ventricular dysfunction, heart failure), GI (nausea and vomiting, diarrhoea, hepatocellular dysfunction). HIGH mortality rate, ITU level care.
What triggers thyroid storms?
Surgery, Chuildbirth, acute severe illness (infection, trauma, DKA, stroke, PE)
Describe transient mild thyrotoxicosis
1-2m (always resolves), beta blockers if required, cold isotope scan, anti-thyroid drugs will not work
Describe (longer) hypothyroid phase of thyroiditis
4-6m, 80% normal at 1 yr. May require thyroxine tx.
When should you consider thyroiditis?
Pregnant women/within 1 year post partum, Patitent with very tender thyroid (may be raised inflammatory markers), clinical status does not fit lab results, no diagnostic features of Graves, current/recent hep c tx with interferon
Describe features of goitres in euthyroid patients.
Common, more so in iodine deficient areas, may be multinodular, usually nothing to worry about
What should you do when finding a thyroid nodule in a euthyroid patient?
exclude thyroid cancer (~5%), ultrasound scan, FNA biopsy for cytology
Name 5 autoimmune diseases associated with thyroid disease
T1D, pernicious anemia, coeliac disease, premature ovarian failure, Addision’s disease
What medications may patients with thyroid disease already be on, due to associated conditions?
Lithium, Amiodarone
Name 2 syndromes associated with thyroid disease.
Down’s Syndome, Turner Syndrome
