97. Thyroid Flashcards

1
Q

In patients with established thyroid disease, do not check thyroid-stimulating hormone levels too often, but rather test at the appropriate times, such as when ? (3)

A
  • after changing medical doses.
  • when following patients with mild disease before initiating treatment.
  • periodically in stable patients receiving treatment.
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2
Q

When examining the thyroid gland, use proper technique. Explain how.

A
  • from behind the patient, ask the patient to swallow)
  • especially to find nodules (which may require further investigation).
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3
Q

Name Risk Factors for Thyroid Disease (6)

A
  • Women >45yo
  • Postpartum. No clear impact (benefit or harm) for universal screening in pregnancy
  • Radiation
  • Drug-induced (lithium, amiodarone)
  • Autoimmune disease (eg. DM1)
  • Strong family history of thyroid disease
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4
Q

Describe effect of lithium on thyroid (3)

A
  • can cause goiter
  • hypothyroidism (more common)
  • hyperthyroidism
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5
Q

Describe effect on thyroid : Interferon alfa-2b (2)

A

may cause hypothyroidism or hyperthyroidism

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6
Q

Name sx : Hypothyroidism (8)

A
  • Mood: Depression
  • Memory
  • Motor: Fatigue/Lethargy
  • Mass: Weight gain
  • Metabolism: Cold intolerance
  • Menstrual irregularities
  • Constipation
  • Dry skin
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7
Q

Name sx : Hyperthyroidism (7)

A
  • Palpitations/ tachycardia/ atrial fibrillation
  • Widened pulse pressure
  • Nervousness and tremor
  • Heat intolerance
  • Weight loss
  • Muscular weakness
  • Usually goiter is present
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8
Q

What to do if TSH high (> 4-5 mU/L) (2)

A

Possible Primary Hypothyroidism
* FT4 to determine degree of hypothyroidism
* Anti-TPO Ab once

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9
Q

What to do if TSH low (<0.2mU/L)

A

Possible Primary Hyperthyroidism
* Free T4 and T3 to determine degree of hyperthyroidism
* If no obvious cause (eg. Graves - new ophthalmopathy, goiter)
(1) Thyrotropin receptor antibodies (TRAb)
(2) Radioactive iodine uptake (contraindicated in pregnant/breastfeeding)
(3) Ultrasound with thyroidal blood flow

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10
Q

If abnormal thyroid size, nodules, what to do ?

A
  • Thyroid ultrasound
  • FNA for nodules >1cm or 5mm and suspicious features (r/o cancer)
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11
Q

Name DDX primary hypoT4 (7)

A
  • Chronic autoimmune thyroiditis
  • Iatrogenic
  • Iodine deficiency/excess
  • Drugs
  • Infiltrative diseases
  • Transient hypothyroidism
  • Congenital thyroid disease
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12
Q

Name iatrogenic causes of hypoT4 (4)

A
  • thyroidectomy
  • radioiodine therapy
  • external radiation
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13
Q

Name drugs that cause hypoT4 (7)

A
  • thionamides
  • lithium
  • amiodarone
  • interferon-alfa
  • interleukin-2
  • perchlorate
  • tyrosine kinase inhibitors
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14
Q

Name Infiltrative diseases that cause hypoT4

A
  • thyroïdite fibreuse
  • hémochromatose
  • sarcoïdose
    *
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15
Q

Name : Transient hypothyroidism (4)

A
  • Thyroïdite (lymphocytaire silencieuse, granulomateuse subaiguë, post-partum)
  • Thyroïdectomie subtotale
  • Thérapie à l’iode radioactif pour Graves
  • Arrêt des doses suppressives d’hormones thyroïdiennes chez les patients euthyroïdiens
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16
Q

Name central hypoT4 causes (2)

A
  • TSH deficiency
  • TRH deficiency
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17
Q

Name types of HypoT4 (3)

A
  • Primary
  • Central
  • Résistance généralisée aux hormones thyroïdiennes
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18
Q

Name ddx avec hyperT4 : Normal/high radioiodine uptake (4)

A
  • Autoimmune
  • Tissu thyroïdien autonome
  • TSH-mediated
  • Human chorionic gonadotropin
19
Q

Name autoimmune hyperT4 ddx (2)

A
  • Graves’ disease
  • Hashitoxicosis
20
Q

Name Autonomous thyroid tissue
hyperT4 ddx (2)

A
  • Toxic adenoma
  • Toxic multinodular goiter
21
Q

Name Human chorionic gonadotropin
hyperT4 ddx (2)

A
  • Hyperemesis gravidarum
  • Trophoblastic
21
Q

Name TSH-mediated
hyperT4 ddx (1)

A

Pituitary adenoma

22
Q

Name Thyroiditis
hyperT4 ddx (5)

A
  • Subacute granulomatous (de Quervain’s) thyroiditis
  • Painless thyroiditis (silent, lymphocytic, postpartum)
  • Amiodarone
  • Radiation thyroiditis
  • Palpation thyroiditis
23
Q

Name ddx avec hyperT4 : Near absent radioiodine uptake (3)

A
  • Thyroiditis
  • Exogenous thyroid hormone intake (excessive replacement therapy)
  • Ectopic hyperthyroidism
24
Q

Name Ectopic hyperthyroidism
hyperT4 ddx (2)

A
  • Struma ovarii
  • Metastatic follicular thyroid cancer
25
Q

Name causes : Subclinical hypothyroidism (5)

A
  • possible CAD
  • heart failure
  • stroke
  • lipids
  • infertility
26
Q

Describe tx : Subclinical hypothyroidism (2)

A
  • Consider treatment if TSH≥20mU/L, symptomatic, or risk (elevated Anti-TPO Ab, Goiter, strong family history of autoimmune, pregnancy)
  • Consider treatment in infertility
27
Q

Name risks : Subclinical hyperthyroidism

A
  • atrial fibrillation/flutter
  • heart failure
  • lower Bone Mineral Density
28
Q

Desribe tx : Subclinical hyperthyroidism

A

Consider treatment if TSH <0.1 mIU/L and
* Symptomatic (palpitations, tremor, nervousness)
* >65yo
* Comorbidities such as heart disease or osteoporosis
* Postmenopausal (<65yo) and not taking estrogen/bisphosphonates

29
Q

Describe tx : Subacute granulomatous thyroiditis (viral infection, painful thyroid) (1)

A

NSAIDs

30
Q

Treatment of Hypothyroidism (5)

A
  • Levothyroxine treatment of choice, start 12.5-50mcg/day
  • Target TSH euthyroid range (except in secondary hypothyroidism, where target FT4)
  • No evidence for levothyroxine in euthyroid (except in thyroid cancer target undetectable TSH to reduce recurrence by 40%)
  • Avoid TSH <0.1mIU/L
  • Consider higher serum TSH target in elderly and hospitalized (eg. 8)
31
Q

Describe ris TSH < 0.1mlU/L

A
  • thyrotoxicosis
  • A-fib
  • osteoporosis
32
Q

Describe follow-up tx hypoT4 (4)

A
  • Repeat TSH q3-4 months until stable, then yearly
  • If dose higher than expected, evaluate for GI disorder (H pylori gastritis, atrophic gastritis, celiac)
  • Follow serum TSH when started on medications, change in body weight, aging, pregnancy
  • Poor adherence, weekly levothyroxine should be considered
33
Q

Describe tx : Myxedema coma (7)

A
  • Altered mental status
  • hypoventilation
  • hypothermia
  • hypotension
  • bradycardia
  • hypoNa
  • hypoglycemia
34
Q

Describe tx : Myxedema coma (4)

A
  • Levothyroxine (T4) loading dose 200-400mcg IV, then 1.6mcg/kg/day IV
  • Liothyronine (T3) 5-20mcg followed by 2.5-10mcg q8h given with T4
  • Glucocorticoids (hydrocortisone 100mg IV q8-12h x2d) until coexisting adrenal insufficiency can be excluded
  • Supportive measures (ventilation, fluids, correction of hyponatremia and hypothermia)
35
Q

What to do if elevated TSH vs low TSH ?

A
  • Elevated TSH, rule out pituitary gland tumour
  • Low TSH, consider radioiodine uptake scan
36
Q

Describe tx : Graves (3)

A
  • Thionamides (Methimazole - MMI or Propylthiouracil - PTU)
  • Beta-blockers (for symptom control) : Atenolol 25-50mg daily (up to 200mg) until goal HR<90
  • Ophthalmopathy: Steroids, radiation, surgical decompression
37
Q

Describe tx : Thyroiditis (3)

A
  • NSAIDs
  • Steroids
  • Beta-blockers for symptomatic treatment
38
Q

Describe tx : Toxic adenoma/multinodular goiter (2)

A
  • First-line: Radioiodine or surgery. May consider thionamide initially for short-term
  • Beta-blockers for symptomatic treatment
39
Q

Name sx : Thyroid storm (6)

A
  • Hyperthermia
  • Tachycardia
  • N/V/D
  • Dehydration
  • Delirium
  • Coma
40
Q

Name causes : Thyroid storm (3)

A
  • Trauma
  • Surgery
  • Radioactive Iodine
41
Q

Describe tx : Thyroid storm (5)

A
  • B-Blockers (Propranolol 60-80mg q4-6h)
  • PTU 200mg PO q4h
  • Iodine solution (delayed 1h after PTU)
  • Iodinated radiocontrast
  • High-dose IV hydrocortisone 100mg IV q8h
42
Q

escr

A