6 renal pathophysiology

Renal Pathology

Introduction:

• 150gm: each kidney

• 1700 liters of blood filtered 180 L of G. filtrate

1.5 L of urine / day.

• Kidney is a retro-peritoneal organ

• Blood supply: Renal Artery & Vein

• One half of kidney is sufficient – reserve

• kidney function: Filtration, Excretion, Secretion,

Hormone synthesis.

Kidney Location:

Kidney Anatomy:

Renal Pathology Outline

• Glomerular diseases: Glomerulonephritis

• Tubular diseases: Acute tubular necrosis

• interstitial diseases: Pyelonephritis

• Diseases involving blood vessels: Nephrosclerosis

• Cystic diseases

• Tumors

Clinical Syndromes:

• Nephritic syndrome.

– Oliguria, Haematuria, Proteinuria, Oedema.

• Nephrotic syndrome.

– Gross proteinuria, hyperlipidemia,

• Acute renal failure

– Oliguria, loss of Kidney function - within weeks

• Chronic renal failure.

– Over months and years - Uremia

Introduction

• Functions of the kidney:– excretion of waste products

– regulation of water/salt

– maintenance of acid/base balance

– secretion of hormones

• Diseases of the kidney– glomeruli

– tubules

– interstitium

– vessels

• Azotemia: BUN, creatinine

• Uremia: azotemia + more problems

• Acute renal failure: oliguria

• Chronic renal failure: prolonged uremia

Abnormal findings

• Hematuria

• Oliguria

• Azotemia

• Hypertension

Nephritic syndrome

• Massive proteinuria

• Hypoalbuminemia

• Edema

• Hyperlipidemia/-uria

Nephrotic syndrome

Glomerular diseases

– Nephrotic syndrome

• Minimal change disease

• Focal segmental glomerulosclerosis

• Membranous nephropathy

– Nephritic syndrome

• Post-infectious GN

• IgA (immune) nephropathy

Nephrotic Syndrome

• Massive proteinuria

• Hypoalbuminemia

• Edema

• Hyperlipidemia

• Adults: systemic disease (diabetes)

• Children: minimal change disease

• Characterized by loss of foot processes

• Good prognosis

Causes

Minimal change disease

Minimal change disease Normal glumerular structure

Normal glomerulusMinimal change disease

Focal Segmental Glomerulosclerosis

• Primary or secondary

• Some (focal) glomeruli show partial

(segmental) hyalinization

• Unknown pathogenesis

• Poor prognosis

Focal segmental glomerulosclerosis

Membranous Glomerulonephritis

• Autoimmune reaction against unknown renal antigen

• Immune complexes

• Thickened GBM

• Subepithelial deposits

Membranous glomerulonephritis

Nephritic Syndrome

• Hematuria

• Oliguria, azotemia

• Hypertension

• Post-infectious GN, IgA nephropathy

• Immunologically-mediated

• Characterized by proliferative changes and

inflammation

Causes

Post-Infectious Glomerulonephritis

• Child after streptococcal throat infection

• Immune complexes

• Hypercellular glomeruli

• Subepithelial humps

Post-infectious glomerulonephritis

IgA Nephropathy

• Common!

• Child with hematuria after (URI) Upper

Respiratory Infection

• IgA in mesangium

• Variable prognosis

IgA nephropathy

• Tubular and interstitial diseases

– Inflammatory lesions

• pyelonephritis

Pyelonephritis

• Invasive kidney infection

• Usually ascends from UTI

• Fever, flank pain

• Organisms: E. coli, Proteus

• Women, elderly

• Patients with catheters or mal-formations

• Dysuria, frequency

• Organisms: E. coli, Proteus

Urinary Tract Infection

Acute pyelonephritis with abscesses

Pyelonephritis

Cellular cast

Chronic pyelonephritis

Drug-Induced Interstitial Nephritis

• Antibiotics, NSAIDS

• IgE and T-cell-mediated immune reaction

• Fever, eosinophilia, hematuria

• Patient usually recovers

• Analgesic nephritis is different (bad)

Drug-induced interstitial nephritis

Acute Tubular Necrosis

• The most common cause of ARF!

• Reversible tubular injury

• Many causes: ischemic (shock), toxic (drugs)

• Most patients recover

Acute tubular necrosis

Benign Nephrosclerosis

• Found in patients with benign hypertension

• Hyaline thickening of arterial walls

• Leads to mild functional impairment

• Rarely fatal

Benign nephrosclerosis

Malignant nephrosclerosis

• Arises in malignant hypertension

• Hyperplastic vessels

• Ischemia of kidney

• Medical emergency

• 5% of cases of hypertension

• Super-high blood pressure, encephalopathy, heart

abnormalities

• First sign often headache, scotomas

• Decreased blood flow to kidney leads to increased

renin, which leads to increased BP!

• 5y survival: 50%

Malignant Hypertension

Malignant hypertension

Adult Polycystic Kidney Disease

• Autosomal dominant

• Huge kidneys full of cysts

• Usually no symptoms until 30 years

• Associated with brain aneurysms.

Adult polycystic kidney disease

Childhood Polycystic Kidney Disease

• Autosomal recessive

• Numerous small cortical cysts

• Associated with liver cysts

• Patients often die in infancy

Childhood polycystic kidney disease

Medullary Cystic Kidney Disease

• Chronic renal failure in children

• Complex inheritance

• Kidneys contracted, with many cysts

• Progresses to end-stage renal disease

• Tumors

– Renal cell carcinoma

– Bladder carcinoma

Renal Cell Carcinoma

• Derived from tubular epithelium

• Smoking, hypertension, cadmium exposure

• Hematuria, abdominal mass, flank pain

• If metastatic, 5y survival = 5%

Renal cell carcinoma

Bladder Carcinoma

• Derived from transitional epithelium

• Present with painless hematuria

• Prognosis depends on grade and depth of invasion

• Overall 5y survival = 50%

Bladder carcinoma