395.2 📚 國考版（醫師國考 / PGY OSCE）

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395.2.0.1 📌 Cram Sheet

395.2.0.1.1 🔥 高 yield 12

1. HPT axis: TRH → TSH → T4/T3 → negative feedback
2. TSH 第一線 (除 central)
3. T4 主分泌 (90%), T3 主活性 (5x), rT3 inactive
4. 80% T3 來自 peripheral T4 → T3 (D1, D2 deiodinase)
5. TBG 75% carrier; free T4 bioactive
6. TPO + H₂O₂ organify iodine
7. MIT + DIT → T3; DIT + DIT → T4
8. PTU 抑 TPO + D1; methimazole 抑 TPO only
9. Anti-TPO Hashimoto > Graves’; TRAb/TSI Graves’
10. Tg post-thyroidectomy + RAI 才有意義
11. Calcitonin = MTC marker
12. ¹³¹I 孕婦/哺乳禁忌

395.2.0.1.2 🔢 必背

項目	數字
TSH 正常	0.4-4.0 mU/L
Free T4	0.8-1.7 ng/dL
Free T3	2.3-4.2 pg/mL
Iodine RDA adult	150 μg/d
Iodine RDA pregnant	250 μg/d
RAIU normal 24h	10-30%
Iodine contrast → RAI delay	6 週
TSH 1st trimester	0.1-2.5 mU/L

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395.2.0.2 ⭐ 高 yield

395.2.0.2.1 TFT Patterns

TSH	FT4	解讀
↑	↓	Primary hypothyroidism
↑	normal	Subclinical hypothyroidism
↓	↑	Primary hyperthyroidism
↓	normal	Subclinical hyperthyroidism
↓	↓	Central hypothyroidism
↑	↑	TSH-oma / thyroid resistance

395.2.0.2.2 TBG

• ↑: pregnancy, OCP, HRT, hepatitis
• ↓: nephrotic, cirrhosis, malnutrition, severe illness
• Use free T4 to circumvent

395.2.0.2.3 Antibodies

Ab	Disease	Sensitivity
Anti-TPO	Hashimoto	95%
Anti-TPO	Graves’	50-70%
Anti-Tg	Hashimoto	60-80%
TRAb	Graves’	95%
TSI	Graves’ subset	specific

395.2.0.2.4 Imaging Quick

Test	Use
US neck	1st line nodule
TI-RADS	FNA decision
RAIU	Hyperthyroid etiology (high vs low)
¹²³I scan	Hot vs cold
MIBG	Pheo (not thyroid)

395.2.0.2.5 Drug Effects on TFT

Drug	Effect
Amiodarone	Hypo or hyper (Type 1 vs 2)
Lithium	Hypo (block release)
Iodine excess	Wolff-Chaikoff (transient hypo); Jod-Basedow (hyper in nodular)
Steroid	↓ TSH, ↓ T3 (low T3 syn)
Heparin	↑ free T4 (artifact in vitro)
Estrogen	↑ TBG → ↑ total T4
Phenytoin / carbamazepine	↓ free T4 (bind)
Bexarotene	central hypothyroidism

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395.2.0.3 🎯 自我檢測

1. HPT axis trophic? → TRH → TSH → T4/T3
2. TSH α subunit shared? → LH/FSH/hCG
3. T4 vs T3 activity? → T3 5x more potent
4. T4 → T3 enzymes? → D1 (peripheral), D2 (CNS, pituitary)
5. Carrier % thyroid? → TBG 75%
6. PTU vs MMI difference? → PTU 抑 D1 (storm 用)
7. Anti-TPO Hashimoto sensitivity? → 95%
8. TRAb Graves’? → 95%
9. Tg use case? → Post-thyroidectomy + RAI surveillance
10. Calcitonin? → MTC marker
11. RAIU normal 24h? → 10-30%
12. Iodine contrast → RAI delay? → 6 週
13. ¹³¹I 孕婦? → 絕對禁忌
14. Hot nodule cancer risk? → < 1%
15. Cold nodule cancer? → 5-15%

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