97. Thyroid Flashcards
Limitez le dépistage de la dysfonction thyroïdienne aux patients dont la probabilité prétest de résultats anormaux est élevée.
Nommez des examples.
(1) ceux qui présentent les symptômes ou les signes classiques d’une dysfonction thyroïdienne ;
(2) ceux dont les signes ou les symptômes sont atypiques, mais qui sont à plus grand risque d’avoir cette maladie
* les personnes âgées
* les femmes en période postpartum
* les patients ayant des ATCD de fibrillation auriculaire
* les patients atteints d’une endocrinopathie
Chez le patient dont la dysfonction thyroïdienne est bien établie, ne vérifiez pas trop souvent les taux de thyréostimuline (TSH) ; faites-le plutôt à des moments appropriés, par exemple quand ?
- après avoir ajusté la posologie médicamenteuse ;
- lors du suivi des patients ayant une forme légère de thyroïdopathie ou avant de commencer le traitement ;
- périodiquement chez les patients traités, mais dont l’état est stable.
Lorsque vous examinez la glande thyroïde, utilisez la technique appropriée, c-à-d comment ?
(c.-à-d. placez-vous derrière le patient et demandez-lui d’avaler), particulièrement pour trouver des nodules (lesquels peuvent nécessiter une investigation plus poussée).
Name Risk Factors for Thyroid Disease (6)
- 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
Describe effect of lithium on thyroid (3)
- can cause goiter
- hypothyroidism (more common)
- hyperthyroidism
Describe effect on thyroid : Interferon alfa-2b (2)
may cause hypothyroidism or hyperthyroidism
Name sx : Hypothyroidism (8)
- Mood: Depression
- Memory
- Motor: Fatigue/Lethargy
- Mass: Weight gain
- Metabolism: Cold intolerance
- Menstrual irregularities
- Constipation
- Dry skin
Name sx : Hyperthyroidism (7)
- Palpitations/ tachycardia/ atrial fibrillation
- Widened pulse pressure
- Nervousness and tremor
- Heat intolerance
- Weight loss
- Muscular weakness
- Usually goiter is present
What to do if TSH high (> 4-5 mU/L) (2)
Possible Primary Hypothyroidism
* FT4 to determine degree of hypothyroidism
* Anti-TPO Ab once
What to do if TSH low (<0.2mU/L)
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
If abnormal thyroid size, nodules, what to do ?
- Thyroid ultrasound
- FNA for nodules >1cm or 5mm and suspicious features (r/o cancer)
Name DDX primary hypoT4 (7)
- Chronic autoimmune thyroiditis
- Iatrogenic
- Iodine deficiency/excess
- Drugs
- Infiltrative diseases
- Transient hypothyroidism
- Congenital thyroid disease
Name iatrogenic causes of hypoT4 (4)
- thyroidectomy
- radioiodine therapy
- external radiation
Name drugs that cause hypoT4 (7)
- thionamides
- lithium
- amiodarone
- interferon-alfa
- interleukin-2
- perchlorate
- tyrosine kinase inhibitors
Name Infiltrative diseases that cause hypoT4
- thyroïdite fibreuse
- hémochromatose
- sarcoïdose
*
Name : Transient hypothyroidism (4)
- 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
Name central hypoT4 causes (2)
- TSH deficiency
- TRH deficiency
Name types of HypoT4 (3)
- Primary
- Central
- Résistance généralisée aux hormones thyroïdiennes
Name ddx avec hyperT4 : Normal/high radioiodine uptake (4)
- Autoimmune
- Tissu thyroïdien autonome
- TSH-mediated
- Human chorionic gonadotropin
Name autoimmune hyperT4 ddx (2)
- Graves’ disease
- Hashitoxicosis
Name Autonomous thyroid tissue
hyperT4 ddx (2)
- Toxic adenoma
- Toxic multinodular goiter
Name Human chorionic gonadotropin
hyperT4 ddx (2)
- Hyperemesis gravidarum
- Trophoblastic
Name TSH-mediated
hyperT4 ddx (1)
Pituitary adenoma
Name Thyroiditis
hyperT4 ddx (5)
- Subacute granulomatous (de Quervain’s) thyroiditis
- Painless thyroiditis (silent, lymphocytic, postpartum)
- Amiodarone
- Radiation thyroiditis
- Palpation thyroiditis
Name ddx avec hyperT4 : Near absent radioiodine uptake (3)
- Thyroiditis
- Exogenous thyroid hormone intake (excessive replacement therapy)
- Ectopic hyperthyroidism
Name Ectopic hyperthyroidism
hyperT4 ddx (2)
- Struma ovarii
- Metastatic follicular thyroid cancer
Name causes : Subclinical hypothyroidism (5)
- possible CAD
- heart failure
- stroke
- lipids
- infertility
Describe tx : Subclinical hypothyroidism (2)
- Consider treatment if TSH≥20mU/L, symptomatic, or risk (elevated Anti-TPO Ab, Goiter, strong family history of autoimmune, pregnancy)
- Consider treatment in infertility
Name risks : Subclinical hyperthyroidism
- atrial fibrillation/flutter
- heart failure
- lower Bone Mineral Density
Desribe tx : Subclinical hyperthyroidism
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
Describe tx : Subacute granulomatous thyroiditis (viral infection, painful thyroid) (1)
NSAIDs
Treatment of Hypothyroidism (5)
- 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)
Describe follow-up tx hypoT4 (4)
- 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
Describe tx : Myxedema coma (7)
- Altered mental status
- hypoventilation
- hypothermia
- hypotension
- bradycardia
- hypoNa
- hypoglycemia
Describe tx : Myxedema coma (4)
- 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)
What to do if elevated TSH vs low TSH ?
- Elevated TSH, rule out pituitary gland tumour
- Low TSH, consider radioiodine uptake scan
Describe tx : Graves (3)
- 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
Describe tx : Thyroiditis (3)
- NSAIDs
- Steroids
- Beta-blockers for symptomatic treatment
Describe tx : Toxic adenoma/multinodular goiter (2)
- First-line: Radioiodine or surgery. May consider thionamide initially for short-term
- Beta-blockers for symptomatic treatment
Name sx : Thyroid storm (6)
- Hyperthermia
- Tachycardia
- N/V/D
- Dehydration
- Delirium
- Coma
Name causes : Thyroid storm (3)
- Trauma
- Surgery
- Radioactive Iodine
Describe tx : Thyroid storm (5)
- 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
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