UCSF Renal Teaching Materials

Pediatric Nephrology Resident Handbook:

https://www.dropbox.com/scl/fi/xqa6yh1yqu7ird2gissg3/Paediatric-Nephrology-Resident-Handbook-Final-1.pdf?rlkey=qbcmdjbme7y9x2m3ylbcrd6gl&e=1&dl=0

Dehydration

• Dehydration Classification

  • Minimal:<3% body weight loss
  • Mild:3-5% loss
  • Moderate:6-9% loss
  • Severe:≥10% loss

• Severe Dehydration Signs

  • Mental: Apathetic, lethargic, unconscious
  • Cardiovascular: Tachycardia (possible bradycardia), weak pulse, low BP
  • Physical: sunken fontanelle, absent tears, prolonged capillary refill, decreased skin fold recoil
  • Extremities: Cold, mottled, cyanotic, thready pulses

• Fluid Therapy Phases

  1. Resuscitative: Restore tissue perfusion
  2. Titration: Transition from boluses to maintenance
  3. Maintenance: Homeostatic balance
  4. Convalescent: Stop exogenous fluids

• IV Fluid Bolus calculations

  • The recommended pediatric bolus dose is 10 mL/kg to 20 mL/kg, which may be repeated as needed.

• Maintenance Fluid calculations

  

  • Method 1: 4 2 1 rule
    • Maintenance Fluids Calculator
  • Method 2
    • Weight <10 kg: 100 mL/kg
    • Weight ≥10 kg: 1000 mL (first 10 kg) + 50 mL/kg (each kg over 10)

• Dextrose-containing fluids

  • Give to hypoglycemic patients
  • Usually added to maintenance IVF
  • Careful in hypokalemic patients

Electrolytes

• Hyponatremia (<135 mEq/L)

  • Causes: Impaired water excretion, hypotonic fluid intake

    

  • Treatment: Isotonic saline for volume depletion, careful correction rate

    • isotonic saline has a higher concentration of sodium (154 mEq/L) and correction of hypovolemia decreases ADH secretion, which allows urinary excretion of excess water

  • If hyponatremia is symptomatic (seizures, AMS):

    • hypertonic saline bolus at 3 mL/kg to 5 mL/kg of 3% NaCl

    • Once acute central nervous system symptoms have resolved, the remaining sodium correction should occur at a rate less than 8 mEq/L to 12 mEq/L in 24 hours.

    • Goal is correction of serum Na at a rate of 2 mEq/L per hour with a goal of raising serum Na by 5 mEq/L in the first several hours

      

• Hypernatremia (>145 mEq/L)

  

  • Correction:
    • Total correction fluid volume = Free water deficit + ongoing maintenance fluid needs
    • Free water deficit (mL) = lean body weight (kg) * 0.6[(patient’s Na/140) - 1]
    • Correct slowly! (≤0.5 mEq/L per hour)
  • Prevent: Cerebral edema

Younger kids have higher serum potassium

• Hypokalemia (Serum Potassium Below Normal for Age)

  • Caused by decreased intake, increased losses (renal or GI), or intracellular shifts

    

  • Severe hypokalemia can cause cardiac arrhythmias and muscle weakness.

  • Evaluation involves assessing for underlying causes and ECG.

  • Tx: Oral or IV K repletion, with careful monitoring