Thyroid DOs (5 questions) Flashcards
Most common thyroid conditions?
Hypothyroidism
Thyrotoxicosis (Hyperthyroidism)
Thyroid Nodules
Gender ratio of hypothyroidism?
10 women:1 man
Most common age of hypothyroidism?
>50yo
Overt vs subclinical hypothyroidism?
Overt: clinical syndrome + elevated TSH and decreased T4 or T3
Subclinical: no typical Sx but elevated TSH and normal circulating thyroid hormone
Who would you screen for thyroid dos? And how?
- Screen high risk populations
- older women
- individuals with autoimmunine disorders
- individuals with a strong family Hx of thyroid disease
- hx of radioactive iodine Tx or head/ neck irradiation
- use of med that impair thyroid fx (e.g. contains iodine – amiodarone)
- Screening test: Measure serum TSH
Symptoms of hypothyroidism
- slowing of metabolic processes: fatigue & weakness, cold intolerance, DOE, wt gain, cognitive dysfunction, mental retardation (infantile onset), constipation, growth failure
- Accumulation of matrix substances: dry skin, hoarseness, edema
- Other: decreased hearing, myalgia and paresthesias, depression, menorrhagia, arthralgia, pubertal delay
Signs of hypothyroidism
- slowing of metabolic processes: slow movement and slow speech, delayed relaxation of DTRs, bradycardia, carotenemia
- Accumulation of matrix substances: coarse skin, puffy face and loss of eyebrows, periorbital edema, enlargement of tongue
- Other: diastolic HTN, pleural and pericardial effusions, ascites, galactorrhea
What is hyperthyroidism?
thyrotoxicosis (lot o thyroid hormone) caused by excessive production of thyroid hormone
Overt vs subclinical hyperthyroidism
- overt: symptomatic, low TSH, high elevated free thyroxine (T4) or free triiodothyronine (T4) levels
- Subclinical: suppressed TSH but T4 and T3 are wnl, no Sx hyperthyroid
Who tends to get hyperthyroid (gender / age)?
women over 50yo
Most common causes of hyperthyroidism?
- Diffuse toxic (hyperfunctioning) goiter
- Graves’ disease
- Toxic multinodular goiter
- Toxic uninodular goiter
- Thyroid inflammatory diseases (e.g., Hashimoto’s thyroiditis)
- Postpartum thyroiditis, and subacute thyroiditis
Clinical features of hyperthyroidism
- heat intolerance
- warm moist skin
- increased sweating
- nervousness, irritability, eyelid retraction
- weakness, myopathy
- SOB, palpitations, arrhythmias, heart failure
- increased appetitie, frequent BMs, wt loss
- Scanty periods
- eye and skin changes of Grave’s (stare, lid lag, exophthalmos)
- hair thinning, brittle
- hyperpigmentation of skin, pruritis and hives
- onycholysis (Plummer’s nails)
Normal TSH
0.5 - 4.5/4.7
(some argue lower limit of 2.5)
Normal T3
3.5 - 6.5 pmol/L
Normal T4
0.7 - 1.4 ng/mL
What test results would you expect in primary hypothyroidism?
- Increased TSH -usually the only one ordered
- Decreased T4
- anti-thyroid Abs if Hashimoto’s
- Reduced radioactive iodine uptake and thyroid scintiscan (not usually ordered)
Clinical mgmt of primary hypothyroidism
- Eliminate thyrotoxic meds/exposure
- Rx L-thyroxine (synthetic T4)
What is a clear cut time to start pharm mgmt of hypothyroidism
TSH>10mU/L
FT4
L-thyroxine: is it necessary to start slow?
Not if young and healthy. Yes if >50 w/underlying cardiac conditions, if elderly (>70), or anyone w/severe ischemic heart disease
When would you refer for hypothyroidism?
Typically primary care, but refer if:
- 18 years old or younger
- unresponsive to therapy, or pregnant (pregnant, usually need to increase T4)
- cardiac disease, goiter, nodule, or other structural abnormality of thyroid gland
- coexisting endocrine disease (eg., pituitary disease)
Most common causes of hyperthyroid in young v elderly
- younger pts: Graves’ diz and thyroiditis (postpartum)
- elderly: toxic nodular goiter and/or occur in those being Tx’ed w/ amiodarone
What is “apathetic hyperthyroidism”?
hyperthyroidism without hyperadrenergic symptoms
How do elderly often present w/hyperthyroidism?
atrial fib, weight loss, in the absence of “classic” symptoms
What test results would you expect in hyperthyroidism?
- usually decreased TSH
- T4 and T41 usually increased
- T3 usually increased
- antithyroid Abs increased in Grave’s
- Increased radioactive iodine uptake and thyroid scintiscan
Clinical mgmt of hyperthyroidism
- Reduce iodine intake (iodine can actually increase or decrease)
- BB
- Consult with M.D. re: use of anti-thyroid medications or iodine
- Refer to M.D. for ablative therapy/surgery
- Overt hyperthyroidism: refer to specialists
- Pending referral, β-blocker to control Sxs if not contraindicated (eg., atenolol 25-50mg qd or propranolol 20-40mg 3-4times a day, HR
- If a long wait is likely before pt is seen by a specialist-initiate treatment with anti-thyroid drugs in consultation with the endocrinologist concerned.
How is hyperthyroidism treated?
- Radioiodine Ablation: RAI (131 I) – depends on thyroid size. Normally total ablation, which leads to hypothyroidism and lifelong L-thyroxine
- Antithyroid Drug – prior to ablation
- Surgery – typically for toxic adenoma, malignancy
What antithyroid drugs are available?
Tapazole (methimazole) and propylthiouracil (PTU)
How do Tapazole (methimazole) and propylthiouracil (PTU) work?
interfere with thyroid hormone synthesis
PTU is also able to inhibit T4 to T3 conversion in peripheral tissues
Who is most likely to be Rxed Tapazole or PTU?
- young adults, persons with mild thyrotoxicosis, small goiter
- Do not permanently damage the thyroid
- High recurrence rate with drug approach – 3 to 6mths later until PT decides to do more invasive procedure (maybe 50% do have permanent remission.). Tx usually about 1.5 years
When would you decide to treat a subclinical thyroid dz?
- women w/ subclinical hypo-T who are pregnant or trying to conceive or pt w/ typical sxs of hypo-T
- pt w/ increased risk of AF or osteoporosis (Tx parameters)
Characteristics of a thyroid nodule you would only monitor?
- not changed for years
- asymptomatic
- non-palpable, found incidentally,
Characteristics of a thyroid nodule you would send out for a non-urgent referral?
- abnormal thyroid test
- Hx of sudden onset of pain in a thyroid lump (likely to have bled into a benign thyroid cyst)
- a thyroid lump which is newly presenting or increasing in size over month
Characteristics of a thyroid nodule you would send out for an urgent referral (2 weeks)?
- Notably large size (> 4cm)
- rapid growth
- pain
- hard consistency
- fixation to adjacent structures
- local LAN
- stridor (refer same day) and hoarseness
Clinical mgmt of benign thyroid nodules
Watchful waiting vs. L-thyroxine suppressive therapy
Clinical mgmt of malignant thyroid nodules
- Surgery
- Radiation
- L-thyroxine suppressive/replacement therapy
Pt presents with amiodarone induced hyperthyroidism. What do you do?
- potential for life threatening cardiac effects (work w/cardiologist & endocrinologist. Can’t just stop it).
- Key role: check thyroid function test before starting amiodarone, after 3-4 months of therapy and 1 year after discontinuing therapy (every 6 month)
Why does amiodarone induce hyperthyroidism?
Amiodarone contains substantial amt of iodine. Also, has long half life! Must continue to monitor!
