🧪 Renal Function [Neurosurgery Wiki]

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====== 🧪 Renal Function ======

**Renal function** refers to the ability of the kidneys to **filter blood**, **eliminate waste products**, and **maintain fluid, electrolyte, and acid-base balance**. It also plays a key role in the **clearance of many drugs**, including anticoagulants and contrast agents.

===== 📊 Key Measurements =====
  * **Serum Creatinine (sCr)**: primary marker; influenced by age, muscle mass
  * **Estimated Glomerular Filtration Rate (eGFR)**:
    * Calculated via CKD-EPI or MDRD formulas
    * Normal >90 mL/min/1.73 m²
  * **Creatinine Clearance (CrCl)**:
    * Useful for drug dosing (e.g., dabigatran)
    * Calculated via Cockcroft-Gault formula

===== 💉 Clinical Relevance =====

=== 💊 Drug Clearance ===
  * Renal function determines elimination of:
    * **Dabigatran**, **enoxaparin**, **vancomycin**, **contrast media**
  * Impaired renal function increases **risk of toxicity** or **delayed drug clearance**
  * Always assess before:
    * **Contrast-enhanced imaging**
    * **Anticoagulant dosing**
    * **Nephrotoxic antibiotics**

=== 🧠 Neurosurgery Context ===
  * **Dabigatran**: requires renal dose adjustment; reversal urgency ↑ in renal impairment
  * **Contrast-induced nephropathy**: risk with repeated CT/MRI contrast in elderly or ICU patients
  * **Surgery planning**: electrolyte control, fluid balance, uremia-related bleeding risk

===== ⚠️ Red Flags =====
  * Rapid rise in serum creatinine
  * Oliguria (<0.5 mL/kg/h)
  * Elevated BUN/creatinine ratio
  * Acid-base or electrolyte disturbances (↑K⁺, ↓HCO₃⁻)

===== ✅ Best Practice =====
  * Always document **baseline renal function** pre-intervention
  * Use **eGFR/CrCl** to adjust drug doses
  * In patients >70 years or on nephrotoxic agents, monitor **daily renal profile**
  * Avoid contrast or nephrotoxins when possible in acute impairment

===== 🔗 Related Entries =====
  * [[dabigatran_reversal_in_mild_traumatic_brain_injury]]
  * [[anticoagulation_reversal_protocol]]
  * [[postoperative_complications]]
  * [[delayed_bleeding]]