Week 8 - Renal and Urinary dysfunction

Question 1

Define Chronic Kidney Disease

Answer 1

• A complex disease caused by a variety of different pathophysiological conditions
• It is a progressive loss of renal function over a period of months or years by.

Question 2

What is the Pathophysiology of Chronic Kidney Disease (CKD) relating to Anaemia

Answer 2

• In CKD, damaged kidneys produce less erythropoietin (EPO) → reduced stimulation of red blood cell (RBC) production in bone marrow.
• Additionally, uremia shortens RBC lifespan and causes nutritional deficiencies (e.g., iron, B12).
• Result: normocytic normochromic anaemia, leading to fatigue, pallor, and reduced oxygen delivery to tissues.

Question 3

What is the Pathophysiology of Chronic Kidney Disease (CKD) relating to Hyperkalaemia

Answer 3

• Impaired renal excretion of potassium due to nephron damage.
  Potassium accumulates in the blood → serum K⁺ levels rise.
• Can lead to cardiac arrhythmias and muscle weakness.
• Contributing factors: acidosis, medications (e.g., ACE inhibitors, spironolactone).

Question 4

What is the Pathophysiology of Chronic Kidney Disease (CKD) relating to Confusion (8 marks)

Answer 4

• Caused by uremic toxin accumulation (e.g., ammonia, creatinine, urea) due to reduced clearance.
• These toxins impair neurotransmitter function and contribute to encephalopathy.
• May also result from electrolyte imbalances (e.g., hyponatraemia) or acidosis.
• Symptoms: lethargy, confusion, disorientation, possibly seizures.

Question 5

Explain the pathophysiology of acid base imbalance (metabolic acidosis) that can occur with kidney injury

Answer 5

• Healthy kidneys maintain acid–base balance by excreting hydrogen ions (H⁺) and reabsorbing bicarbonate (HCO₃⁻).
• In kidney injury (acute or chronic), nephron damage reduces these abilities:
  1. ↓ H⁺ excretion
• H⁺ ions accumulate in the blood, leading to acidaemia (↓ pH).
  2. ↓ HCO₃⁻ reabsorption
• Less bicarbonate is reclaimed → loss of buffering capacity.
  3. Accumulation of metabolic acids
• Uremic toxins (e.g., sulphates, phosphates) build up, worsening acidosis.
  4. Consequences of metabolic acidosis:
• Bone demineralisation (buffering with calcium phosphate)
• Muscle wasting
• Kussmaul respirations (compensatory deep breathing)
• Worsening of hyperkalaemia (H⁺ moves into cells, K⁺ moves out)

Question 6

What are the Pathophysiology and Examples of the Prerenal Acute Renal Failure Causes

Answer 6

Prerenal – Decreased blood flow to the kidneys
- Caused by hypovolemia, shock, heart failure, or severe dehydration.
- Leads to reduced glomerular filtration rate (GFR) and ischemia.
- Potentially reversible if perfusion is restored early.

Question 7

What are the Pathophysiology and Examples of the Intrarenal Acute Renal Failure Causes

Answer 7

Intrarenal - Direct damage to kidney tissue
- Damage to glomeruli, tubules, or interstitium from toxins, drugs (e.g., aminoglycosides), glomerulonephritis, or acute tubular necrosis (ATN).
- Disrupts filtration and tubular function, impairing urine formation and solute clearance.

Question 7

What are the Pathophysiology and Examples of the Postrenal Acute Renal Failure Causes

Answer 7

Postrenal - Obstruction of urine outflow
- Caused by urinary tract obstruction (e.g., kidney stones, enlarged prostate, tumors).
- Back pressure increases in nephrons → reduces GFR and causes kidney damage.