Kidney Failure Overview

Aug 11, 2025

Overview

This lecture explains acute and chronic kidney (renal) failure, including causes, hallmark symptoms, diagnostic labs, and high-priority nursing interventions, with emphasis on details most often tested in nursing exams.

Types of Renal Failure

  • Acute Kidney Injury (AKI): Sudden loss of kidney function, often reversible if treated promptly.
  • Chronic Kidney Disease (CKD): Gradual, long-term damage to the kidneys leading to permanent loss of function.
  • Untreated AKI can progress to CKD.

Causes & Pathophysiology of AKI

  • Pre-renal: Decreased kidney perfusion from low blood flow (e.g., hypovolemia, shock, heart failure, clots).
  • Intra-renal: Direct damage to kidney tissues, often from nephrotoxic drugs (contrast dye, aminoglycosides, NSAIDs) or infections.
  • Post-renal: Obstruction after the kidneys (e.g., kidney stones, tumors, enlarged prostate/BPH).

Key Lab Values & Assessments

  • Creatinine >1.3 mg/dL signals bad kidney function.
  • BUN >20 mg/dL indicates poor urine filtration.
  • Urine output <30 mL/hr or <400 mL/day (oliguria) means kidney distress.
  • Metabolic acidosis: pH <7.35 due to retention of hydrogen ions.
  • 1,500 mL urine output in 24 hours is a sign of good renal function.

Phases of Acute Renal Failure

  • Onset (initiation): Beginning of injury.
  • Oliguric: Low urine output (<400 mL/24hr), high specific gravity.
  • Diuretic: Excessive urine output (3-6 L/day), low specific gravity.
  • Recovery: Gradual return to normal function (may take up to 1 year).

Causes & Progression of CKD

  • Most common: Uncontrolled diabetes, hypertension, chronic glomerulonephritis.
  • Risk increased by age, autoimmune diseases, polycystic kidney disease.
  • Stages based on GFR: Stage 4 (15-29); Stage 5 (<15, end-stage, requires dialysis/transplant).

Signs, Symptoms & Complications of CKD

  • Oliguria (very low urine output).
  • Fluid volume overload: Hypertension crisis (headache, nausea, mental status changes), lung crackles, JVD.
  • Anemia (decreased erythropoietin).
  • Uremic frost (crystallized urea on skin), pruritus.
  • Elevated electrolytes: Hypernatremia (>145), hyperphosphatemia (>4.5), hypocalcemia (risk of fractures), hyperkalemia (>5.0).

Hyperkalemia: Signs & Emergency Treatments

  • EKG changes: Peaked T waves (K+ 6-7), ST elevation (K+ 7-8), wide QRS (>8).
  • Symptoms: Weakness, lethargy, bradycardia, dysrhythmias (can be fatal).
  • Priority treatment:
    1. IV calcium gluconate (for dysrhythmias).
    2. IV insulin + dextrose (to shift K+ into cells).
    3. Kayexalate and dialysis (slower options).

Diagnostic Tests & Nursing Interventions

  • Creatinine clearance test: 24-hr urine collection on ice, discard first urine.
  • Monitor daily weights (1 kg gain = 1 L retained fluid).
  • Avoid nephrotoxic drugs (NSAIDs, certain antibiotics, contrast dye).
  • Report significant fluid retention and hypertensive crisis signs immediately.

Key Terms & Definitions

  • Creatinine — Waste product filtered by kidneys; marker of renal function.
  • GFR (Glomerular Filtration Rate) — Blood volume filtered by kidneys per minute.
  • Oliguria — Urine output <400 mL per day.
  • Hyperkalemia — High potassium, dangerous to the heart.
  • Uremic frost — White, crystalline deposits of urea on skin.
  • Erythropoietin — Hormone from kidneys stimulating RBC production.
  • Dialysis — Machine filtration of blood to replace kidney function.

Action Items / Next Steps

  • Review causes and phases of AKI and CKD.
  • Memorize critical lab values and emergency treatments for hyperkalemia.
  • Practice 24-hr urine collection protocol.
  • Avoid and educate about nephrotoxic drugs in at-risk patients.

Full transcript