22 CFR Notes on Haemodialysis and Dialysis Dementia

Cardiovascular System, Biological Fluids, Renal Function (CFR) CFR.22

Overview of Excretion
  • Primary Organs of Excretion: The kidneys are the principal organs responsible for the removal of liquid waste from the body.
  • Excretion Processes:
    • Kidneys: Filter blood to remove waste products and excess fluid, producing approximately 1.5 L of urine daily.
    • Skin: Eliminates dead cells and sweat.
    • Lungs: Excrete waste gases.
Kidney Functions
  • Main Functions of Kidneys:
    • Remove metabolic wastes such as urea, uric acid, and creatinine.
    • Regulate blood pH through bicarbonate ion (HCO3-) production and phosphate buffer regulation.
    • Estimated Blood Filtration: An average adult purifies around 150 L of blood daily.
Impaired Kidney Function
  • Common Causes of Kidney Disease:
    • Diabetes and high blood pressure are the most prevalent causes.
    • Severe conditions may require dialysis or renal transplantation.
  • Kidney Damage Sources: Include infections, poisoning, lesions, tumors, kidney stones, and circulatory issues.
Uremic Poisoning
  • Definition: Accumulation of nitrogenous waste products (commonly excreted via urine) in the bloodstream, becoming potentially life-threatening.
  • Accumulated Waste Products:
    • Urea: 21 g/day (from amino acid breakdown).
    • Creatinine: 1.8 g/day (from muscle creatine phosphate breakdown).
    • Uric Acid: 480 mg/day (from RNA recycling).
Formation of Kidney Stones
  • Mechanism: Uric acid forms crystals if the rate of formation exceeds elimination, leading to conditions like gout or kidney stones.
  • Gout: Caused by sodium urate crystals precipitating in joints, resulting in inflammation and potential arthritis.
Chronic Kidney Disease (CKD)
  • Definition: Progressive loss of kidney function characterized by a decreased glomerular filtration rate (GFR).
  • Consequences:
    • Salt and water retention leading to edema.
    • Increased acidosis risk (pH < 6.8 can be fatal).
    • Nitrogenous waste accumulation causing uremia.
End Stage Renal Disease (ESRD)
  • Description: Occurs when up to 80% of kidney function is lost before symptoms become evident.
  • Causes: Chronic conditions such as diabetes, hypertension, genetic diseases, or medication overuse.
Treatment for Kidney Failure
  • Dialysis: A procedure for removing dissolved impurities from the bloodstream using a semipermeable membrane.
    • Hemodialysis: Clean blood directly using an artificial membrane.
    • Peritoneal Dialysis: Utilizes the body's peritoneal membrane as a filter.
  • Dialysis Process:
    • Dialysis solutions (dialysate) are isotonic with blood to prevent net loss of essential components.
Dialysis Dementia
  • Observation: More than 10% of kidney patients on home dialysis show neurological issues like stuttering, twitching, and slurred speech.
  • Cause: High aluminum content in the water supply, as aluminum cannot be excreted due to compromised kidney function.
Key Learning Outcomes
  • Recognition of primary organs of excretion and their functions.
  • Understanding uremic poisoning and its implications.
  • Knowledge of kidney stones, chronic kidney diseases, and their manifestations.
  • Comprehension of dialysis processes and associated risks such as dialysis dementia.