Glomerular Diseases and Kidney Anatomy

Glomerular Diseases

• Glomerular diseases are a group of conditions that damage the glomeruli, the kidney's microscopic filtration units.
• Damage impairs kidney function, leading to proteinuria (excess protein in urine), hematuria (blood in urine), reduced glomerular filtration rate (GFR), and in severe cases, chronic kidney disease or kidney failure.
• Glomerular diseases have significant morbidity and mortality, leading to complications like hypertension, nephrotic syndrome, and end-stage renal disease.

Kidney Anatomy

• The kidney has an outer cortex and an inner medulla.
• Blood vessels (renal artery and vein) and the ureter connect to the kidney.
• The nephron is the functional unit, consisting of the glomerulus, Bowman's capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.
• The glomerulus is a network of capillaries that filters blood.
• The Bowman's capsule surrounds the glomerulus.

Renal Anatomy

• The glomerulus is a network of capillaries filtering blood.
• The proximal convoluted tubule is the first part of the tubule system.
• The loop of Henle is a U-shaped loop that moves the filtrate from the cortex to the medulla.
• The distal convoluted tubule is the last part of the tubule system
• The collecting duct collects the filtrate from the distal convoluted tubules.
• Nephrons are the functional units of the kidney.

Glomerulus Detail

• The glomerulus consists of capillary loops with fenestrations in the endothelium.
• The glomerular basement membrane sits between the endothelium and podocytes.
• Podocytes have foot processes that wrap around the capillaries, creating filtration slits.
• Mesangial cells are found within the glomerulus.

Classification of Glomerular Diseases

• Primary glomerulonephritis (GN): disease affects the kidney only.
  • Minimal change disease (Lipoid nephrosis)
  • Acute diffuse proliferative GN: Post-streptococcal GN, Non-post-streptococcal GN
  • Rapidly progressive GN
  • Membranous GN
  • Membranoproliferative GN
  • Chronic GN
• Secondary GN: disease affects the kidney and other organs.
  • Systemic lupus erythematosus (SLE)
  • Polyarteritis nodosa (PAN)
  • Wegener granulomatosis
  • Diabetes mellitus (diabetic nephropathy)
  • Goodpasture syndrome
  • Amyloidosis

Diagnosis of Glomerular Diseases

• Renal biopsy is taken to study glomerular disease.
• Light microscopy examines glomeruli, tubules, and interstitium.
• Immunofluorescence microscopy detects immunoglobulin deposits in the glomeruli.
• Electron microscopy detects the site of the immune complex deposits, such as sub-epithelial, sub-endothelial, mesangial or basement membrane.

Minimal Change Disease

• Often affects children
• Characterized by an excellent prognosis
• Usually responds well to corticosteroids
• Histological findings include fusion of foot processes of podocytes without immune complex deposits.

Post-Streptococcal GN

• Often begins after a streptococcal infection.
• Characterized by an acute inflammatory response.
• Light microscopy shows proliferation of endothelial and mesangial cells.
• Immune complex deposition occurs, leading to acute inflammation

Membranous Glomerulopathy

• Characterized by thickening of the glomerular basement membrane.

Membranoproliferative GN (MPGN) (Type I)

• Includes mesangial and endocapillary proliferation, seen as lobular accentuation and double-contoured capillary walls.
• Glomerular immune complex deposits are seen.

Diabetic Glomerulosclerosis

• Results from long-term diabetes
• Thickened glomerular basement membranes with mesangial matrix increase

Amyloidosis

• Deposition of amyloid protein in the kidneys
• Amorphous material is visible on light microscopy.

Anti-GBM Disease (Goodpasture's Syndrome)

• Characterized by circulating antibodies against non-collagenous domains of collagen type IV.
• Leads to glomerular and alveolar basement membrane damage.
• Renal biopsy will show glomeruli necrosis.

IgA Nephropathy

• Characterized by frequent gross/microscopic hematuria
• Mesangioproliferative (most common) is a defining feature on IF.

Henoch-Schönlein Purpura

• Systemic vasculitis that commonly manifests with purpuric rash, abdominal pain, arthralgias, and renal manifestations (IgA nephropathy).

Systemic Lupus Erythematosus (SLE)

• Multi-system autoimmune disease.
• Common in women.
• Kidney involvement (lupus nephritis) causes variable morphological changes.

Chronic Glomerulonephritis

• Associated with chronic kidney damage to glomeruli, tubules, and blood vessels.
• Often characterized by diffuse interstitial fibrosis and bilateral kidney contraction.

Nephrotic Syndrome

• Characterized by: proteinuria, hypoproteinemia, edema, and hyperlipidemia.
• Minimal change disease (MCD) is a common cause in children.
• Membranous nephropathy is a common cause in adults.
• Diagnosis often requires a renal biopsy.
• Complications may include an elevated risk of infection, thromboembolism, and hyperlipidaemia

Nephritic Syndrome

• Characterized by: haematuria, oliguria, periorbital edema, and hypertension.
• Post-streptococcal GN is a typical cause in children.

Pyelonephritis

• Infection of the kidney tissue (tubules, interstitium, and renal pelvis)
• Acute pyelonephritis is typically caused by bacterial infection;
• Chronic pyelonephritis is frequently caused by urinary tract reflux or obstruction.
• Symptoms typically include fever, flank pain.

Acute Interstitial Nephritis (AIN)

• Characterized by diffuse interstitial infiltrates with numerous inflammatory cells, particularly lymphocytes and eosinophils.
• Often triggered by medications (e.g., antibiotics, NSAIDs) or infections.
• Typically associated with an abrupt decline in kidney function, often needing immediate treatment.

Lower Urinary Tract Infections (UTIs)

• Infections affecting the bladder/ureters/urethra
• UTIs usually present with symptoms like painful urination, urgency, frequency

Obstructive Uropathy

• Obstruction to the flow of urine in the urinary tract resulting in hydronephrosis
• Causes can include kidney stones, tumors, and strictures (narrowing within the urinary tract)

Urolithiasis (Renal Calculi)

• Formation of masses of crystals, protein, or various foreign bodies within the urinary tract that can lead to obstruction.
• Common types include Calcium oxalate, Struvite, Uric acid and Cystine
• Factors promoting stone formation include stasis, high concentration of stone components, dehydration, and pH alteration.
• Typical presentation is pain (renal colic), hematuria, and recurrent UTIs

Renal Tumors

• Includes benign and malignant cases.
• The most common malignant tumor is the clear cell renal cell carcinoma.
• Other types include oncocytoma, nephroblastoma.

Tumors of Urinary Bladder/Urothelial Tract

• Primarily affect urothelial cells lining the urinary bladder and ureter.
• Includes benign and malignant tumors, with malignant tumors presenting with more severe clinical outcomes
• Commonly include Urothelial Papilloma, Invasive Urothelial Carcinoma, Pure squamous cell carcinoma and Adenocarcinoma

This quiz covers glomerular diseases, their impact on kidney function, and the anatomy of the kidney. Participants will learn about kidney structures such as the glomerulus and the nephron, as well as the implications of glomerular damage. Test your knowledge and understanding of these critical aspects of renal health.