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12 Cards in this Set
- Front
- Back
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Describe Thyroid Gland anatomy, and blood supply.
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- Bilobed gland connected by an isthmus
- Anterior to the trachea at about the second or third tracheal ring - Blood supply via four main arteries - Two paired superior thyroid arteries from the external carotid artery - Two paired inferior thyroid arteries from the thyrocervical trunk - Venous drainage pairs arterial blood supply |
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What is the hypothalamic-pituitary thyroid axis?
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-Hypothalamus secretes thyrotropin-releasing hormone (TRH)
-In response to TRH, the anterior pituitary releases thyroid-stimulating hormone (TSH) -TSH stimulates the formation of thyroxine (T4) and triiodothyronine (T3) hormones -T4 and T3 negatively feed back on the hypothalamus and pituitary |
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What are some Thyroid Function Tests
and Laboratory evaluation of thyroid function? |
TSH test
Measures the amount of thyroid-stimulating hormone in the blood Used to diagnose thyroid dysfunction T4, Total Used to assess thyroid function and to monitor replacement and suppressive therapy Free T4 Used in patients who may have protein abnormalities that could affect total T4 levels T3, Total and Free T3 Used primarily to diagnose hyperthyroidism Less useful in diagnosis of hypothyroidism since other non-thyroid diseases can decrease T3 levels by decreasing conversion of T4 to T3 in the liver. |
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What is Hyperthyroidism?
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Encompasses a heterogeneous group of disorders, such as:
Graves’ disease Toxic multinodular goiter (TMNG) Solitary toxic adenoma Patients with hyperthyroidism may have variable presentations |
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What are some Signs & Symptoms of Hyperthyroidism?
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Nervousness and irritability
Palpitations and tachycardia Heat intolerance or increased sweating Tremor Weight loss or gain Frequent bowel movements and sometimes diarrhea Exertional intolerance and dyspnea Sleep disturbances (including insomnia) Menstrual disturbance (decreased flow) Impaired fertility Changes in vision, photophobia, eye irritation, diplopia, or exophthalmos Fatigue and muscle weakness Pretibial myxedema (in patients with Graves’ Disease) |
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What will be found in the Physical Examination with Hyperthyroidism?
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Weight and blood pressure
Pulse rate and cardiac rhythm Tachycardia Atrial fibrillation Thyroid palpation and auscultation Thyroid size Nodularity Vascularity Eye examination Exophthalmos Lid retraction Lid lag |
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What will be found in the Neurological Examination with Hyperthyroidism?
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Tremor
Hyperreflexia |
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What would be encompass a comprehensive exam for Hyperthyroidism?
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Neuromuscular examination
Dermatologic examination Cardiovascular examination Lymphatic examination |
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What is the Etiology/Pathophysiology of Graves’ Disease?
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Caused by an activating autoantibody that targets the TSH receptor
Thyroid-stimulating antibodies (TSAb) bind to the TSH receptor, ultimately leading to increased production of thyroid hormone |
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What is the Epidemiology of Graves’ Disease?
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Most common cause of hyperthyroidism
More common in women, female-to-male incidence ratio of ~7 to 10:1 |
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What is the Clinical Presentation of Graves’ Disease?
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Signs/symptoms of hyperthyroidism
50% of patients present with exophthalmos Localized dermal myxedema can occur in 0.5% to 4.3% of patients with Graves’ disease Myxedema can present as asymmetric, raised, firm, pink-to-purple, brown plaques of nonpitting edema Myxedema of Graves’ disease usually occurs in the anterior leg - “pretibial myxedema” |
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What are some studies for test Thyroid function?
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Ancillary Studies
Laboratory evaluation TSH: suppressed (i.e. below normal) Free T4: usually elevated Free T3: helpful if Free T4 normal Thyroid autoantibodies: ex: Thyroid-stimulating hormone receptor antibodies *Note: If TSH is inappropriately normal or high and Free T4 is high, consider thyroid hormone resistance or TSH- secreting pituitary adenoma (rare) |
