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IV Fluids and Other Electrolytes (Including Phosphorous)


Additional References: 
Treatment of hypophosphotemia

Treatment of Hypophosphatemia (MKSAP Nephro Text)

HYPERPHOSPHOTEMIA: -- 2/2 (CKD, Increased Cell turnover, Cell Injury, Exogenous administration) – Rx.

a.     Phosphate binder in CKD (esp if Ca x PO43- >55)

b.    Hemodialysis is Acute Phosphate Nephropathy

c.     Hemodialysis if tumor lysis syndrome with severe hyperphosphatemia (serum phosphate >10 mg/dL [3.23 mmol/L]) and concomitant oliguria

  • Key Concepts to Understand 
    • First: 
      • Most important thing is to understand the electrolyte composition of normal body fluids, and the replacement fluid. 
        • If you do not know this, you will not have a true understanding of which fluid to replace in which circumstances.
    • Second:
      • You must know the normal physiological distribution of body fluid. Also, you should know the expected distribution of replacement fluids. 
    • Third
      • Fluid that you are repleting should resemble normal physiological fluid as much as possible. 
    • Fourth:
      • Fluid you are replacing should not cause drastic change in electrolyte composition. 
    • Fifth:
      • You should reassess the need of fluid every day. 
  • Normal Maintainance Requirement: BMJ 2015
    • Water: 25-30 mL/kg/day
    • Sodium, potassium, and chloride: up to 1 mmol/kg/day 
    • Glucose: 50-100 g/day
  • Mechanism of Fluid retention (in CHF, Liver failure, Nephrotic Syndrome)
    • Increased sodium retention due to RAAS (more than oncotic pressure theory)
      • However, ARB and ACEI does not work very well
      • Aldactone ofcourse does
    • Furosemide when given causes dilution of medullary gradient thus affecting the free water retention 
    • Also, diuresis is more effective if patient is in supine position due to decreased RAAS while in supine position
  • References:
BMJ 2014;350:g7620 

N Engl J Med 2013;369:1243-51

Distribution of IV Fluid in Body on Replacement
BMJ 2014;350:g7620 

N Engl J Med 2013;369:1243-51

Lancet 2012; 379: 2466–76 

Lancet 2012; 379: 2466–76