394.3 🩺 內科專科考前版

394.3.0.1 📌 䞀頁重點

  • 22E updates:
    • Copeptin (CT-proAVP) — stable surrogate for AVP; hypertonic saline + copeptin test 可取代 traditional water deprivation
    • Tolvaptan: V2 antagonist FDA approved for SIADH + ADPKD; LFT monitoring (hepatotoxicity); 30-day limit in some indications
    • Renaming: ICRP suggests “AVP-D” (deficiency) and “AVP-R” (resistance) instead of “central / nephrogenic DI” — 22E mostly still uses DI terminology
    • ICI-related posterior pituitary involvement uncommon (anterior more common)
  • Taiwan: 健保 desmopressin (oral, intranasal) for CDI; thiazide / amiloride for NDI; tolvaptan 條件

394.3.0.2 🌟 Pearls (15)

394.3.0.2.1 Diagnosis
  1. Copeptin > 4.9 pmol/L after hypertonic saline → primary polydipsia (rules out CDI)
  2. Direct copeptin > 21.4 pmol/L without stim → CDI / NDI confirmed
  3. Water deprivation test still useful but copeptin gaining ground
  4. MRI bright spot absent → CDI confirmed; sometimes 郚分 cases 仍 has it
  5. Stalk thickening → workup for granulomatous (sarcoid, LCH), germinoma, IgG4-RD, hypophysitis
394.3.0.2.2 SIADH Management
  1. Tolvaptan: V2 antagonist; aquaresis without Na loss; LFT monitoring; 30-day limit some indications; expensive
  2. Conivaptan: IV V1a + V2 antagonist; acute use only
  3. Salt tablets + loop diuretic combo: increases free water clearance
  4. Demeclocycline: induces NDI; rarely used now (nephrotoxicity)
  5. Urea oral: osmotic; well tolerated; 22E option
394.3.0.2.3 Correction Pitfalls
  1. Re-lowering Na if over-corrected: D5W IV + desmopressin 鹜氎 IV; controversial but recommended for severe over-correction
  2. High-risk for ODS: chronic SIADH, malnutrition, alcoholism, hypokalemia, hypophosphatemia, liver disease
394.3.0.2.4 NDI
  1. Amiloride for lithium-induced NDI: blocks ENaC → reduces Li uptake into principal cell
  2. NDI from sickle cell medullary damage often irreversible
  3. Vasopressin V1a: pressor effect, used in vasodilatory shock (septic) — not for diabetic insipidus

394.3.0.3 📍 Taiwan + 健保

394.3.0.3.1 CDI
  • 健保 desmopressin (Minirin):
    • Intranasal spray
    • Oral tablet
    • SC injection (peri-op)
  • 健保 vasopressin tannate (older, replaced)
  • MRI sella + stalk imaging 健保
394.3.0.3.2 NDI
  • 健保 thiazide (HCTZ) + amiloride
  • 健保 NSAID 短期
  • æ²» lithium-induced: 健保 lithium dose adjustment
394.3.0.3.3 SIADH
  • 健保 fluid restriction 教育
  • 健保 furosemide
  • 健保 NaCl tablets (條件)
  • 健保 tolvaptan 條件 (短期 acute SIADH; long-term controversial)
  • 健保 conivaptan IV 條件
  • 健保 hypertonic saline (3%) 條件

394.3.0.4 🎓 內專必懂 (15)

  1. 埌葉解剖 + ADH/oxytocin
  2. ADH V1/V2/V3 receptors + 各功胜
  3. SIADH Bartter-Schwartz criteria + 排陀前必須先 thyroid/adrenal
  4. SIADH causes 8 倧類 (paraneoplastic, CNS, pulmonary, drug, nausea/pain, hypothyroid/AI, HIV, hereditary)
  5. CSW vs SIADH 鑑別 (volume status critical!)
  6. Acute hypoNa correction protocol + ODS prevention
  7. Re-lowering Na technique for over-correction
  8. CDI vs NDI + water deprivation + copeptin
  9. CDI causes (idiopathic, tumor, surgery, TBI, infiltrative, genetic)
  10. NDI causes (lithium #1, hypercalcemia, hypokalemia, genetic V2/AQP2)
  11. Wolfram syndrome (DIDMOAD)
  12. Pregnancy DI (placental vasopressinase)
  13. Triphasic post-pituitary surgery + management each phase
  14. Tolvaptan, conivaptan indications + LFT
  15. 22E: copeptin, AVP-D/AVP-R nomenclature, urea, ICRP guideline

394.3.0.5 ⚙ Detailed Hyponatremia Workflow

1. Plasma Osm
   - Normal/high (pseudo-/iso-/hyperosmolar) → not true hypoNa
   - Low (true hypotonic hypoNa) → continue
2. Volume status
   - Hypovolemic: GI loss, diuretic, salt-wasting
   - Euvolemic: SIADH, hypothyroidism, AI, primary polydipsia
   - Hypervolemic: HF, cirrhosis, nephrosis
3. Urine Na
   - < 20: extra-renal (diarrhea, vomiting)
   - > 20: renal (diuretic, AI, salt-wasting, SIADH)
4. Urine Osm
   - < 100: primary polydipsia, beer potomania, "tea + toast"
   - > 100: SIADH, AI, hypothyroidism
5. 排 secondary AI (cortisol stim) + thyroid (TSH)
6. SIADH Bartter-Schwartz

394.3.0.6 ⚙ Severe SIADH (Na < 120 + symptomatic) — 內專 step-by-step

1. ABCs + IV access
2. 3% saline 100 mL IV over 10 min (or 2 mL/kg)
3. Repeat × 1-2 if 仍 seizing / 神經惡化
4. Goal: ↑ Na 4-6 mmol/L within 6 h
5. After symptoms relief, slow correction
6. 24h max ↑ 8-10 (chronic) or 12 (acute < 48h)
7. Q2h Na monitoring initially
8. If over-correction → D5W + desmopressin (re-lower)
9. Long-term: fluid restrict 800-1000 mL/d, treat cause
10. If cabal: tolvaptan / urea / salt + loop diuretic

394.3.0.7 ⚙ Triphasic Post-Pituitary Surgery (CDI/SIADH/CDI)

Phase 1 (Day 0-5): CDI 
  - Stalk damage → ADH 䞍胜 release
  - Polyuria + thirst + 高 Na
  - Treat: small DDAVP doses; allow thirst-driven fluid intake

Phase 2 (Day 5-10): SIADH
  - Stored ADH released uncontrolled from damaged neurons
  - HypoNa, water retention
  - Treat: STOP DDAVP; fluid restrict; sometimes 3% saline if severe

Phase 3 (after Day 10): permanent CDI
  - If neurons die, permanent ADH lack
  - Treat: chronic DDAVP
  - 䜆有些 phase 1 alone resolves (transient CDI 50%)

⚠ Recognition essential — wrong-direction therapy is dangerous

394.3.0.8 📚 內專參考

  • TES 台灣內分泌孞會
  • ICRP “AVP-D/AVP-R” 呜名 (2022)
  • Endocrine Society Hyponatremia Guideline

⚠ AI 草皿。