Renal Dysfunction — Plasma Changes

Water

• Hypervolaemia may occur if oliguric renal failure

Electrolytes

• Renal failure can retard the kidneys ability to eliminate excess potassium
  • Hyperkalaemia
• Sodium relatively preserved
• Acid-Base balance
  • Approx. 80mEq/day of non-volatile acids require elimination daily
    • Renal failure leads to progressive acidosis due to loss of buffering ability and limiting urinary pH of 4.5
  • Loss of renal compensation of respiratory acid/base disturbances
• Renal conversion of 25-hydroxy Vit.D to 1,25,-dihydroxy Vit D promotes GI reabsorption of Ca à lost in renal dysfunction leading to hypocalcaemia and hypophosphataemia

Proteins

• Damage to the glomerular basement membrane (Goodpasture’s Disease, other causes of nephrotic syndrome) can lead to renal elimination of protein and loss of plasma proteins due to increased glomerular filtration
• The kidney’s eliminate nitrogenous waste products of protein metabolism (urea), and uricaemia occurs in renal failure

Other

• Creatinine
  • Metabolite of creatine phosphate, generated at constant rate, and eliminated renally. Increases in renal failure
  • Only after 75% loss of functional nephrons
• Decreased production of Erythropoietin
• Parathyroid hormone increased due to hypocalcaemia

Sakurai 2016

Answer by Sakurai