Hypothyroidism Flashcards
What are the signs and symptoms of hypothyroidism? (8)
- Fatigue
- Weight gain
- Constitution
- Menstrual irregularities
- Depression
- Dry skin
- Intolerance to cold
- Reduced body and scalp hair
What are the complications of hypothyroidism? (7)
- Dyslipidemia
- Coronary HD
- HF
- Impaired fertility
- Pregnancy complications
- Impaired concentration and/or memory
- Rarely myxedema coma (life-threatening medical emergency)
Primary hypothyroidism refers to when the condition arises from the _____________
thyroid gland
What are the causes of hypothyroidism? (5)
- Iodine deficiency
- Autoimmune disease (Hashimoto’s thyroiditis)
- Radiotherapy
- Surgery
- Drugs
What are the causes of secondary hypothyroidism? (2)
- Pituitary disorder
2. Hypothalamic disorder
Primary hypothyroidism is more common in females than males and can be classified as either ________ or ________; both of which may or may not be symptomatic.
overt
subclinical
Overt hypothyroidism is characterised by thyroid stimulating hormone (TSH) levels _________ the reference range and free thyroxine (FT4) levels __________ the reference range
above
below
In subclinical hypothyroidism, TSH levels are ________ the reference range but FT4 and free tri-iodothyronine (FT3) levels are _________ the reference range
above
within
In pregnancy, hypothyroidism is defined as overt based on __________ TSH levels (using trimester-specific reference ranges) regardless of FT4 levels
elevated
What are the aims of treatment in patients with hypothyroidism? (3)
- Alleviate symptoms if present
- Align thyroid function tests within or close to reference range
- Reduce the risk of long-term complications
What information should be explained to patients and their family or carers regarding treatment for hypothyroidism? (Not safety information) (3)
- Some patients may feel well even when their thyroid function tests are outside the reference range
- Even when they have no symptoms, treatment may be advised to reduce the risk of long-term complications
- Symptoms may lag behind treatment changes for several weeks to months
What is the first-line treatment for overt hypothyroidism?
Levothyroxine; aim to maintain TSH levels within the reference range
How should management be modified in patients being treated for hypothyroidism with levothyroxine if symptoms persist even after achieving normal TSH levels?
consider adjusting the dose to achieve optimal well-being whilst avoiding doses that cause TSH suppression or thyrotoxicosis
For patients whose TSH level was very high before starting treatment or who have had a prolonged period of untreated disease, the TSH level can take up to __________ to return to the reference range
6 months
Consider measuring TSH levels every ________ until a stable level has been achieved, then yearly thereafter
3 months
Monitoring free thyroxine (FT4) should also be considered in those who continue to be symptomatic
Due to the uncertainty around the long-term adverse effects and the insufficient evidence of benefit over levothyroxine monotherapy, the use of ______________ is not recommended
natural thyroid extract; Liothyronine (either alone or in combination with levothyroxine) is not routinely recommended for the same reasons
When considering whether to start treatment for subclinical hypothyroidism, take into account features suggesting ________________
underlying thyroid disease
For patients with subclinical hypothyroidism who have a TSH level of______ mIU/L or higher on 2 separate occasions 3 months apart, consider levothyroxine sodium
10
In addition to monitoring of TSH, monitoring of ___________ should only be considered in hypothyroid patients who continue to be symptomatic
free thyroxine (FT4)
For symptomatic patients aged under 65 years with a TSH level above the reference range, but lower than 10 mlU/L on 2 separate occasions 3 months apart, consider a ____________________
6-month trial of levothyroxine sodium
if symptoms do not improve after starting levothyroxine, re-measure TSH and if the level remains elevated, adjust the dose. If symptoms persist when serum TSH is within the reference range, consider stopping levothyroxine
If ___________ hypothyroidism is suspected, refer the patient urgently to an endocrinologist to assess the underlying cause
secondary
For those planning a pregnancy and whose thyroid function tests (TFTs) are not within range, advise _____________ until stabilised on levothyroxine sodium treatment
delaying conception;
If pregnancy is confirmed, urgently measure TFTs; discuss the initiation, or changes to levothyroxine sodium treatment and TFT monitoring with an endocrinologist whilst awaiting review, to reduce the risk of obstetric and neonatal complications
Do females with hypothyroidism who are planning a pregnancy or are pregnant need to be referred to an endocrinologist?
Yes, all of them
If pregnancy is confirmed in a patient with hypothyroidism, what steps should be taken urgently to reduce the risk of obstetric and neonatal complications? (3)
- Urgently measure TFTs
- Discuss the initiation or changes to levothyroxine treatment
- Initiate TFT monitoring with an endocrinologist whilst awaiting review
What are the indications for levothyroxine? (2)
- Primary hypothyroidism
2. Hyperthyroidism (block and replace regimen) in combination with carbimazole
Healthcare professionals are advised that if a patient reports symptoms after changing to a different tablet of levothyroxine, a _________ should be considered
thyroid function test
What is the main contraindication to levothyroxine?
Thyrotoxicosis
What are the main cautions regarding prescription of levothyroxine? (7)
- Cardiovascular disorders
- DM or DI
- HTN
- Elderly
- Long-standing hypothyroidism
- Panhypopituitarism
- Predisposition to adrenal insufficiency
What precautions should be taken when prescribing levothyroxine in a patient with CVD?
Baseline ECG because changes induced by hypothyroidism can be confused with ischemia
What precautions should be taken when prescribing levothyroxine in a patient with DM?
Dose of antidiabetic drugs including insulin may need to be increased
What precautions should be taken when prescribing levothyroxine in a patient with panhypopituitarims?
Initiate corticosteroid therapy before starting levothyroxine
What precautions should be taken when prescribing levothyroxine in a patient with predisposition to adrenal insufficiency?
Initiate corticosteroid therapy before starting levothyroxine
When treating patients with levothyroxine, how should dosage be altered if metabolism increases too rapidly (causing diarrhoea, nervousness, rapid pulse, insomnia, tremors and sometimes anginal pain where there is latent myocardial ischaemia)?
reduce dose or withhold for 1–2 days and start again at a lower dose
How do levothyroxine requirements change during pregnancy?
Increase
How do levels of maternal thyroid hormone affect fetal development?
Excessive or insufficient maternal thyroid hormones can be detrimental to fetus;
Assess maternal thyroid function before conception (if possible), at diagnosis of pregnancy, at antenatal booking, during both the second and third trimesters, and after delivery (more frequent monitoring required on initiation or adjustment of levothyroxine)
Is levothyroxine safe during breastfeeding?
Yes, amount too small to affect tests for neonatal hypothyroidism
What are the side effects of levothyroxine? (22)
(Think symptoms of hyperthyroidism)
Frequency not known
- Angina pectoris
- Anxiety
- Arrhythmias
- Arthralgia
- Diarrhea
- Dyspnea
- Fever
- Flushing
- Headache
- Hyperhidrosis
- Insomnia
- Malaise
- Menstrual irregularities
- Muscle spasm
- Muscle weakness
- Edema
- Palpitations
- Skin reactions
- Thyrotoxic crisis
- Tremor
- Vomiting
- Weight decreased
Can oral iron and levothyroxine be taken together?
No, iron decreases absorption of levothyroxine; administer at least 4 hours appart
(Also antacids, sucralfate, and calcium-containing supplements eg calcium gluconate, calcium lactate, calcium phosphate, calcium chloride, calcium carbonate)
What are the food items that potentially decrease absorption of levothyroxine and should therefore not be taken together? (4)
- Dietary fiber
- Milk
- Soy products
- Coffee
When is the ideal time of day to take levothyroxine?
Preferably 30-60 min before breakfast, caffein-containing liquids (eg coffee or tea) or other medication
