L 45. Thyroid Disorder Flashcards
(51 cards)
4x functions of the thyroid gland
- Hormone production
- Growth
- Development
- Regulation of energy metabolism
Epidemiology of thyroid function x3
- More common in women
- Hypo prevalence increases with pregnancy and age
- Most common dysfunctions = hypothyroidism and hyperthyroidism.
Patient assessment for thyroid dysfunction.
Is routine screening/asymptomatic testing recommended?
1. Patient history
2. Physical examination
3. TSH measures.
Routine screening/asymptomatic testing is not recommended.
High suspicion symptoms of hypothyroidism x2?
Goitre, delayed reflexes
Intermediate suspicion symptoms of hypothyroidism x7
Fatigue Weight gain Cold intolerance Dry/rough/pale skin Constipation Facial swelling Hoarseness.
Low suspicion/non-specific symptoms of hypothyroidism x7
Dry hair/hair loss Muscle cramps/aches Depression Irritability Memory loss Abnormal menstrual cycles Decreased libido
High suspicion symptoms of hyperthyroidism x4
Goitre
Thyroid bruit (sound)
Eyelid lag/droop (Ptosis)
Eye bulging (proptosis)
What does ptosis and proptosis mean?
Ptosis: eyelid droop
Proptosis: bulging eyes
Intermediate suspicion symptoms of hyperthyroidism x7
Fatigue Weight loss Heat intolerance/sweating Fine tremor Increased bowel movements Fast heart rate/palpitations Staring gaze
Low suspicion/non specific symptoms of hyperthyroidism x7
Nervousness Insomnia Breathlessness Light/absent menstrual periods Muscle weakness Warm/moist skin Hair loss
Symptoms of hypothyroidism (x3)
Fatigue/lethargy/sleepiness
Cold intolerance
Dry skin
Hypothyroidism treatment goals x3
Replace missing hormones
Relieve signs and symptoms
Achieve euthyroid state
What is a euthyroid state
Normal thyroid function/TSH within the reference range
… is the synthetic form of T4.
… is converted into the more active form, … in the peripheral tissue via peripheral……
Levothyroxine is the synthetic form of T4.
T4 is converted into the more active form, T3, in the peripheral tissue via peripheral deiodination.
Why is levothyroxine the drug of choice for hypothyroidism?
It is reliable, it relieves symptoms, it is safe, and it stabilises thyroid function tests.
Potential issues with elderly or IHD patients with levothyroxine.
Therefore how must we approach the dosing?
Increased metabolic activity = increased cardiac stimulation = arrythmias, angina, MI
TTherefore need to do initial low dose and then titrate.
Dosing of levothyroxine
Adult: 500-100mcg od before breakfast. Titrate 25-50mcg every 3-4 weeks according to response.
In cautioned patients, consider 25mcg of and adjust by +25mcg every 4 weeks.
What is maintenance dose for levothyroxine in adults in and patients with cautions?
100-200 mcg daily in adults
50-200mcg daily in cautioned patients
Dose adjustments occur for levothyroxine when…
Monitoring timeframes.
Dose is titrated according to blood test results
Monitor TSH 6-8 weeks after initiating treatment.
Adjust if necessary, recheck in 6-8 weeks and check symptoms.
If patient stable, monitor TSH every 6-12 months.
Why is the monitoring of levothyroxine only every 6-8 weeks?
Steady state takes 6-8 weeks to reach therefore show clinical benefit. Must wait until then to determine the effects of the medicine.
ADRs of levothyroxine (at excessive doses)
Hyperthyroidism symptoms:
Diarrhoea, headache, flushing, sweating, fever, heat intolerance
Increased appetite but weight loss
Tachycardia, arrhythmias, palpitations, hypertension
Tremor, restlessness, excitability
Insomnia, muscle cramp, muscular weakness
Menstrual irregularities, impaired fertility
Food/diet interactions of levothyroxine
Many foods/ions decrease the gut absorption of levothyroxine (e.g calcium, iron, antacids, cholestryamine). Therefore should take it on an empty stomach.
Drug-food interactions: soy, high fibre diet.
Drug interactions with Levothyroxine x4
The following CYP inducers increase the metabolism of levothyroxine, therefore an increased dose is required: Phenytoin Carbamazepine Oestrogen (HRT) Rifampicin
Levothyroxine brands x3
Synthroid
Eltroxin
Levothyroxine (mercury Pharma)
