ENDO - Thyroid disease Flashcards
describe the common conditions that can lead to hyper and hypo functioning of the thyroid gland
Hyperthyroidism:
- Autoimmune (Grave’s disease)
- toxic nodular goitre (multinodular or solitary adenoma)
- iodine-induced (radiographic contrast, amiodarone)
- Iatrogenic (too much thyroxine use)
- Transient (thyroiditis)
Hypothyroidism:
- Autoimmune (Hashimoto’s thyroiditis, atrophic thyroiditis)
- Iatrogenic: 131I treatment, thyroidectomy, irradiation
- drugs: iodine excess (lithium, antithyroid drugs)
- iodine deficiency (prevalent in poor countries)
list the clinical features of hyperthyroidism and hypothyroidism
Hyperthyroidism: •Heat intolerance •Loss of weight •Increase in appetite •Increase in sweating •Tremulousness •Anxiety, emotional lability •Loss of hair •Increased frequency of bowel movements •Menstrual irregularity *in elderly pt, hyperthyroidism may have few symptoms/signs
Hypothyroidism:
•Malaise, tiredness, myalgia, depression
•Cold intolerance, constipation, weight gain
•Delayed tendon reflexes, bradycardia, myxoedema, voice change, myopathy, hypothermia, effusions
What are the thyroid function tests and what do they mean?
Check TRH, HSH, free T4
If low T4, high TSH: primary (no negative feedback)
If low T4, low TSH: secondary (pituitary itself is not working)
list the appropriate radiological or nuclear medicine imaging tests to diagnose common thyroid disorders
Thyroid nuclear scan: Tc-99m Pertechnetate commonly used
- Normal: thyroid uptake similar to salivary gland uptake
- Grave’s disease: Homogenous increased uptake (compare with salivary gland)
- Toxic-nodular disease: localised increased uptake with suppression of uptake in the rest
- Multinodular goitre: heterogenous increased uptake
describe the different therapeutic agents used to treat thyroid disease (hyper & hypo)
Hyperthyroidism:
- antithyroid drugs; carbimazole, propylthiouracil
- radioactive iodine (to kill some thyroid cells)
- surgery; if adverse reactions to drugs, cosmetic preference, risk of malignancy
Hypothyroidism:
• Usually thyroxine 75 -150 mcg/day, single dose
•Some patients – 50 or even 25 mcg/day as a starting dose
•Aim for TSH in the low normal range (rather than T4)
explain how to monitor the thyroid status of a patient once treated
- regular check of TFT after 6 weeks of change of medications
How do you diagnose hypothyroidism?
- Check TSH
- Reconfirm elevated TSH, confirm FT4 is low – (some weeks apart?)
- Correlate with symptoms and clinical examination
- Consider a thyroid ultrasound only if there is a palpable goitre
- NO NEED for a nuclear scan (c.f. Hyperthyroidism)
- Anti-thyroid antibodies (anti-thyroid peroxidase - TPO) can sometimes be helpful in this situation – especially if the TSH is borderline elevated
Rx of hypothyroidism
- Usually thyroxine 75 -150 mcg/day, single dose
- Some patients – 50 or even 25 mcg/day as a starting dose
- Aim for TSH in the low normal range (rather than T4)
What are the common mistakes made in treating hypothyroidism?
•Only adjust thyroxine dose after 6-8 weeks
•Do not order a nuclear scan test in hypothyroidism
•There is no hurry except in pregnancy
•To be taken separately from medications that may decrease thyroxine absorption
–Iron tablets
–Calcium tablets
–Antacids
–Cholestyramine
DDx of feeling tired, palpitations, panic, SOB at times, insomnia for 2 months
–Caffeine or cola drinks in excess (COMMON!)
–Thyrotoxicosis
–Anxiety or panic disorder
–A primary pulmonary or cardiac disorder
What should you not forget to ask in a suspected hyperthyroid Hx?
- Intake of caffeine/cola/energy drinks
- use of medications (e.g. amiodarone or any weight-loss inducin drugs etc)
What should you look for in hyperthyroid exam?
–Heart rate and rhythm (any AF?). ECG? –TREMOR –Skin, nail and hair changes (often normal) –Thyroid size, consistency, bruit •May have a diffuse soft goitre •May have a bruit over the thyroid –Usually no cervical lymph nodes
Ix of hyperthyroidism. What do you expect to see?
•TSH is very low – less than 0.1
•FT4 and/or FT3 are elevated
•Re-confirm the result
•Consider a nuclear scan
–Not in pregnancy
–Distinguishes between Graves’ disease, toxic nodular disease, iodine or thyroiditis-induced thyrotoxicosis and factitious
•Antibodies against the TSH receptor are often present in high titres and may help confirm the cause of thyrotoxicosis and provide some prognostic information
Rx of hyperthyroidism
- antithyroid drugs; carbimazole, propylthiouracil. May be curative (need short term) in Grave’s disease but not in toxic nodular disease (need permanently).
- radioactive iodine (to kill some thyroid cells)
- surgery; if adverse reactions to drugs, cosmetic preference, risk of malignancy
Name 2 anti-thyroid drugs used to treat hyperthyroidism
carbimazole, propylthiouracil
