๋ฆฌ์คํฐ๋ก๋ ๋ํธ๋ฅจ
๋ฆฌ์คํฐ๋ก๋ ๋ํธ๋ฅจ์ ๊ฐ์์ ํธ๋ฅด๋ชฌ์ ํ์ฑ ์ธํฌ ํํ์ธ **T3(ํธ๋ฆฌ์์ค๋ํฐ๋ก๋)**์ ํฉ์ฑ ํํ์ ๋๋ค. ๋ ๋ณดํฐ๋ก์ (T4)์ด ๊ฐ์์ ๊ธฐ๋ฅ ์ ํ์ฆ์ ํ์ค 1์ฐจ ์น๋ฃ์ ์ด์ง๋ง, ๋ฆฌ์คํฐ๋ก๋์ T4 ๋ณด์ถฉ์ ๋ฐ์ํ์ง ์๋ ํน์ ํ์ถ์ ์ํด ๋ณด๋ฅ๋ฉ๋๋ค. ์ด๋ฌํ ๋ฌด๋ฐ์์ ์์ฅ๊ด์ T4 ํก์ ์ฅ์ ๋๋ ์ด๋ก ์ ์ผ๋ก ํ์์ค๋ํ ํจ์๋ฅผ ํตํ T4์์ T3๋ก์ ๋ง์ด ์ ํ ๊ฒฐํจ ๋๋ฌธ์ผ ์ ์์ต๋๋ค. **์์ ์์ :** * ๋ฆฌ์คํฐ๋ก๋์ ๋ ๋ณดํฐ๋ก์ ์ ๋นํด **์์ฉ ์๊ฐ๊ณผ ๋ฐ๊ฐ๊ธฐ๊ฐ ํจ์ฌ ์งง์** ๋ ์์ฃผ ํฌ์ฌํด์ผ ํฉ๋๋ค(๋ณดํต ํ๋ฃจ 3ํ). * ํ์ฒญ T3 ๋๋๋ง ์ ์ํํ๊ณ T4 ์์น๋ ๋ฎ๊ฒ ์ ์งํ์ฌ ์ ์์ ์ธ ์์ํ๋ถ-๋ํ์์ฒด-๊ฐ์์ ํผ๋๋ฐฑ ์ถ์ ๋ฐฉํดํ๋ฏ๋ก **์ด๊ธฐ ์น๋ฃ์ฉ์ผ๋ก๋ ๊ถ์ฅ๋์ง ์์ต๋๋ค**. * ์ ์ฒด์ ์์ฐ์ ์ธ ์กฐ์ ์ ํ ๋จ๊ณ(T4 โ T3)๋ฅผ ์ฐํํ๊ธฐ ๋๋ฌธ์ ์์ธ์ฑ ๊ฐ์์ ์ค๋ ์ฆ์ ์ํ์ด ๋ ๋์ต๋๋ค.
์์ฉ ๊ธฐ์ : Thyroid hormones act primarily at the cellular level to regulate metabolism. * **Mechanism:** T3 enters the cell and binds to **nuclear thyroid hormone receptors (TRs)** โ the receptor-hormone complex binds to DNA โ stimulates or inhibits the transcription of specific mRNA โ alters protein synthesis. * **Physiologic Effects:** Increases the metabolic rate of tissues, enhances oxygen consumption, increases body temperature, stimulates gluconeogenesis, and promotes the mobilization and utilization of glycogen stores. * **Cardiovascular Effects:** Increases heart rate, cardiac output, and blood volume by upregulating beta-adrenergic receptors. * **Development:** Crucial for the adequate development of the central nervous system and skeletal growth.
๋๋ฌผ ์ข ๋ณ ์ฉ๋
- Hypothyroidism ยท 4.4 micrograms/kg PO 2-3 times a day ยท PO ยท q8h-q12h
- T3 suppression test (diagnostic for hyperthyroidism) ยท 25 ฮผg ยท PO ยท q8h ยท 7 doses total ยท Administer 7 doses, then measure T4 and T3 on the morning of the 3rd day, 2-4 hours after the 7th dose.
- Hypothyroidism (unresponsive to T4) ยท 4-6 micrograms/kg PO q8h ยท PO ยท q8h ยท Some dogs may require less frequent dosing. Only indicated when T4 supplementation has failed.
- Hypothyroidism (refractory to T4) ยท 4-6 ฮผg/kg ยท PO ยท q8h ยท Not recommended as first-line therapy due to short half-life.
์ฉ๋์ ๋ฉดํ ์์ ์ ๋ฌธ๊ฐ๋ฅผ ์ํ ์์ ์ฐธ๊ณ ์๋ฃ์ ๋๋ค. ํญ์ ์ต์ ๋ผ๋ฒจ๊ณผ ๊ฐ๋ณ ํ์์ ๋ํด ํ์ธํ์ญ์์ค.
ํฌ์ฌ ๊ฒฝ๋ก
๊ธ๊ธฐ
- Acute myocardial infarction
- Thyrotoxicosis
- Untreated adrenal insufficiency
- Untreated adrenal insufficiency (Addison's disease)
์ด์๋ฐ์
- Tachycardia
- Polyphagia
- Polyuria/Polydipsia (PU/PD)
- Excitability
- Nervousness
- Excessive panting
- Apathy or listlessness (seen in about 10% of cats)
- PU/PD (Polyuria/Polydipsia)
- Nervousness/Anxiety
- Panting
- Weight loss
์ฝ๋ฌผ ์ํธ์์ฉ
- Tricyclic/Tetracyclic Antidepressants ยท Increased risk for CNS stimulation and cardiac arrhythmias.
- Antidiabetic Agents (insulin, oral agents) ยท Thyroid hormones may increase the requirements for insulin or oral antidiabetic agents.
- Cholestyramine ยท May reduce liothyronine absorption; separate doses by at least 4 hours.
- Sympathomimetic Agents (epinephrine, norepinephrine) ยท Thyroid hormones can potentiate the cardiovascular effects of sympathomimetics.
- Warfarin ยท Thyroid hormones increase the catabolism of vitamin K-dependent clotting factors, potentially increasing anticoagulation effects.
- Digoxin ยท Potential for reduced digoxin levels and decreased therapeutic effect.
- Ketamine ยท Concurrent use may cause tachycardia and hypertension. ยท moderate
- Sympathomimetics ยท Increased risk of cardiac arrhythmias and coronary insufficiency ยท moderate
- Insulin ยท May alter glucose control, requiring dosage adjustments ยท minor
๋ชจ๋ํฐ๋ง
- Serum T3 levels (draw just prior to dosing and 2-4 hours post-pill)
- Clinical signs of hyperthyroidism/thyrotoxicosis
- Note: Serum T4 levels will remain low during therapy
- Serum T3 levels
- Clinical signs of hyperthyroidism
- Heart rate and rhythm
๊ณผ์ฉ๋
**Chronic Overdosage:** Produces signs of iatrogenic hyperthyroidism, including tachycardia, polyphagia, PU/PD, excitability, nervousness, and excessive panting. Some cats (approx. 10%) may exhibit 'apathetic' hyperthyroidism (listlessness, anorexia). **Treatment:** Reduce dosage or temporarily withhold until signs subside. **Acute Massive Overdosage:** Can produce signs resembling a **thyroid storm**. * **Treatment:** If oral ingestion is recent, reduce absorption using standard protocols (emetics, gastric lavage, activated charcoal, cathartics) unless contraindicated by the patient's clinical status. * **Supportive Care:** Oxygen, artificial ventilation, beta-blockers (e.g., propranolol) for tachycardia/arrhythmias, IV fluids, dextrose, and antipyretic agents as needed.
VetSheet ์ฝ๋ฌผ ๋ ํผ๋ฐ์ค๋ ๋ฉดํ ์์ ์ ๋ฌธ๊ฐ๋ฅผ ์ํ ์์ ์์ฌ๊ฒฐ์ ๋ณด์กฐ ๋๊ตฌ์ด๋ฉฐ, ์ ๋ฌธ์ ํ๋จ์ด๋ ์ ์กฐ์ฌ์ ์ต์ ๋ผ๋ฒจ์ ๋์ ํ์ง ์์ต๋๋ค.