Renal Failure Overview

Renal Failure Overview

• Renal failure can be classified into Acute Renal Failure (ARF) and Chronic Renal Failure (CRF).
• Objectives include understanding anatomy, function, causes, symptoms, and management of both ARF and CRF.

Terminology

• CRF: Chronic Renal Failure
• ARF: Acute Renal Failure
• ESRD: End Stage Renal Disease
• ESRF: End Stage Renal Failure
• GFR: Glomerular Filtration Rate
• Azotemia: Nitrogenous waste retention due to renal insufficiency.

Glomerular Disease

• Nephritis: Inflammation of glomeruli, often presenting with proteinuria and hematuria. Causes include streptococci, SLE, severe acute kidney infections, and some medications.
• Nephrotic Syndrome: Characterized by extensive proteinuria (>3.5 g/day), hyperlipidemia, and edema. Causes include infections (HIV, Hepatitis) and conditions like diabetic nephropathy.

Interstitial/Tubular Disease

• Acute Tubular Necrosis (ATN): A leading cause of ARF in hospitalized patients due to hypotension and nephrotoxins (e.g., aminoglycosides). Urine shows muddy brown granular casts.
• Acute Interstitial Nephritis: Causes include drugs (e.g., NSAIDs, antibiotics), infections, and autoimmune disorders. Urinalysis may reveal eosinophils and white blood cell casts.
• Cast Nephropathy (Multiple Myeloma): Characterized by tubular casts, indicative of renal tubular damage.

Chronic Tubular Disease

• Caused by conditions such as Polycystic Kidney Disease and hypercalcemia, leading to decreased excretion and reduced urinary concentrating ability.
• Renal Tubular Acidosis (RTA) affects acid-base balance, with Proximal RTA resulting in hyperchloremic acidosis. Distal RTA leads to failure in maintaining vital pH gradients.

Acute vs Chronic Renal Failure

• Acute Renal Failure (ARF): Sudden onset, rapid reduction in urine output, often reversible with regeneration of tubular cells. Presenting features include oliguria (<400 mL/day in adults).
• Chronic Renal Failure (CRF): Progressive and irreversible, involving significant nephron loss before symptoms appear (up to 75% functional loss).

Classification of Acute Renal Failure

• Classifications based on urine volume:
  • OLIGURIC: <500 cc/24 hours
  • ANURIC: absence of urine output.
• Classified into:
  • Prerenal: 55% (due to reduced blood flow)
  • Intrinsic: 40% (due to direct damage to renal parenchyma)
  • Postrenal: 5-15% (due to obstructions in urinary tract).

Diagnosis and Management

• Diagnosis of ARF includes monitoring creatinine levels and urine flow rates.
• Management revolves around identifying and treating the underlying cause to prevent further progression.