Renal Pathology Flashcards
How can you classify renal pathology?
According to the part of the nephron that is damaged.
Glomerular:
- Nephrotic syndrome
- Nephritic syndrome
Tubular and interstitial:
- Acute tubular necrosis
- Tubulointerstitial nephritis (acute and chronic pyelonephritis, interstitial nephritis)
Blood vessels:
- Microangiopathic thrombosis (HUS and TTP)
Describe nephrotic syndrome
- Proteinuria (>3g/day)
- Hypoalbuminaemia
- Oedema
Presents with oedema (facial in children, peripheral in adults) and frothy urine
List the primary causes of nephrotic syndrome
- Minimal change disease
- Membranous glomerular disease
- Focal segmental glomerulosclerosis
- Diabetes
- Amyloidosis
Describe minimal change disease
The most common cause of nephrotic syndrome in children. There are no changes on light microscopy with loss of podocyte foot processes on electron microscopy. There are no immune deposits, it reacts well to steroids and less than 5 percent will develop end stage renal failure.
Describe membranous glomerular disease
A common cause of nephrotic syndrome in adults. There is diffuse basement membrane thickening on light microscopy and subepithelial deposits on electron microscopy. There are immune deposits along the entire glomerular basement membrane. There is poor response to steroids and up to 40 percent will develop end stage renal failure within 20 years.
Can be primary or secondary to SLE, infection, drugs or malignancy.
Describe focal segmental glomerulosclerosis
This is a common cause of nephrotic syndrome in adults, especially in afro-Caribbean communities. There is focal and segmental consolidation on light microscopy and electron microscopy shows loss of foot processes. There are is immune deposition in scarred areas and up to 50 percent will respond to steroids. Around half will develop end stage renal failure in 10 years.
It is mainly primary but can be secondary to obesity or HIV nephropathy.
What is nephritic syndrome?
A manifestation of glomerular inflammation:
- Haematuria
- Oliguria
- Proteinuria (less than nephrotic syndrome)
- Hypertension
Name causes of nephritic syndrome
- Acute post infectious glomerulonephritis
- IgA nephropathy
- Rapidly progressive glomerulonephritis
- Hereditary nephritis
- Thin basement membrane disease
Describe acute post infectious glomerulonephritis
Usually 1-3 weeks after a group A alpha haemolytic streptococcal throat infection (strep pyogenes)
- Caused by immune complex deposition
- Haematuria, proteinuria, oedema, HTN
- Raised ASOT
- Light microscopy: increased cellularity
- Fluorescence microscopy: granular deposits of IgG
- Electron microscopy: subendothelial humps
Describe IgA nephropathy
The most common cause of glomerulonephropathy worldwide. Usually 1-2 days after an upper respiratory tract infection.
- Persistent frank haematuria
- Fluorescence microscopy: granular deposition of IgA
Describe rapidly progressive glomerulonephropathy
Also known as crescentic nephropathy. This is the most aggressive GN and can cause end stage renal failure within weeks. Oliguria and renal failure are more prominent. There are three types:
Anti-GBM antibody
- Good pasture’s syndrome
- Liner deposition of IgG in GBM
- Associated with pulmonary haemorrhages
Immune complex
- Caused by SLE, IgA nephropathy, post infectious GN
- Granular IgG deposition on GBM
- Limited organ involvement (except in SLE)
ANCA associated
- Granulomatosis with polyangiitis (with or without eosinophilic)
- Lack of significant immune complex deposition
- Involved vasculitis (skin rashes of pulmonary haemorrhages)
Describe hereditary nephritis
Also known as Alport’s syndrome; a hereditary disease caused by a mutation in type IV collagen alpha 5 chains. It is X linked.
- Nephritic syndrome
- Sensorineural deafness
- Eye disorders (lens dislocation, cataracts)
- Presents in childhood
Describe thin basement disease
Also known as benign familial haematuria. This is diffuse thinning of the GBM, caused by a mutation in type IV collagen alpha 4 chains.
- Asymptomatic microscopic haematuria
- Usually found as incidental finding
- Renal function normal
Describe acute tubular necrosis
The most common cause of acute renal failure. Caused by reduced flow, causing ischaemia.
- Ischaemia: burns or septicaemia or shock
- Nephrotoxins: drugs, contrast agents, heavy metals
Histopathology:
- Short segments of tubular necrosis
Describe causes of tubulointerstitial nephritis
Acute pyelonephritis
- Bacterial infection, usually ascending from UTI by e. coli
- Fever, chills, sweats, flank pain
- IV antibiotics
Chronic pyelonephritis
- Chronic inflammation and scarring of the parenchyma
- Chronic obstruction (calculi or posterior valves)
- Urine reflux
Acute interstitial nephritis
- Hypersensitivity reaction to drugs
- Seen days after administering medication
- Fever, rash, haematuria, eosinophilia
Chronic interstitial nephritis/Analgesic nephropathy
- Long-term analgesic consumption
- Symptoms occur late in disease
- HTN, haematuria, proteinuria, anaemia
