11. Renal involvement in systemic diseases

Question 1

How does amyloidosis affect the kidneys?

Answer 1

• Proteinuria, nephrotic syndrome or progressive renal failure failure
• Common amyloid types are:
  
  • AL (light chain): due plasma dyscrasias (plasma cell disorders and plasma cell proliferative diseases)
  • AA (Serum amyloid A protein deposit): due to chronic inflammatory disease of hereditary diseases like familial mediteranean fever

Question 2

How does diabetes mellitus affect the kidneys?

Answer 2

• DM is one of the most commonc auses of ESRD (18%)
• Contributing factors:
  
  • Diabetic nephropathy (microvascular complication of DM)

1. Early on, glomerular and tubular hypertrophy ==> increased GFR transiently.
2. Later, ongoing damage from advanced glycosylation end-products ==> more destruction
3. They trigger inflammatory responses ==> deposition of type IV collagen and mesangial expansion
4. Arterial hyalinization, thickening of mesangium and GBM, and, nodular glomerulosclerosis

Question 3

What is the progression stages of diabetic nephropathy?

Answer 3

1. Elevated GFR: increased RBF leads to increased GFR ==> microalbuminuria. If glycemia is controlled, it goes back to normal.
2. Glomerular hyperfiltration: in the next 5-10 years, mesangial expansion with hyperfiltration without microalbuminuria
3. Microalbuminuria: When detected, it means the disease has progressed and GFR may be raised or normal (lasts another 5-10 years)
4. Nephropathy: GFR begins to decline and proteinuria increases

Question 4

How do infections affect the kidneys?

Answer 4

• Infection-associated nephropathies are common causes of renal disease
• GN occurs with bacterial, viral and parasitic infections
  
  • E.g. Post-strep GN, HBV, HCV, visceral abscess, syphilis, malaria, schistosomiasis, filiarisis
• Interstitial nephritis occurs with bacterial pyelonephritis, viral (CMS, HIV, HBV), fungal and parasitic (leishmaniasis, toxoplasmosis) infections

Question 5

How do malignancies affect the kidneys?

Answer 5

• Directly:
  
  • Infiltration (leukemia, lymphoma)
  • Obstruction (pelvic tumors)
  • Metastases
• Indirectly:
  
  • _​_Hypercalcemia
  • Nephrotic syndrome
  • AKI
  • Amyloidosis
  • GN
• May also be treatment-associated due to usage of nephrotoxic drugs, tumor lysis syndrome or radiation nephropathy

Question 6

How does multiple myeloma affect the kidneys?

Answer 6

• MM is characterized by excess production of monoclonal antibodies and/or light chains
  
  • Excreted and detected as Bence-Jones proteinuria
  • It causes blockage of tubules by casts made of light chains
    
    • Light chains have a direct toxic effect on tubular cells ==> ATN
• It may be excpressed as:
  
  • AKI
  • CKD
  • Amyloidosis
  • Hypercalcemic nephropathy

Treament:

• High fluid intake may prevent further impairement
• Dialysis may be required in AKI
  
  • It may be possible to remove light chains using special filters

Question 7

How does rheumatoid arthritis affect the kidneys?

Answer 7

• NSAIDs may cause interstitial nephritis
• Penicillamine and gold cause membranous nephropathy
• AA amyloidosis occurs in 15% of RA

Question 8

How does SLE affect the kidneys?

Answer 8

• Involves the glomeruli in 40-60% of adults ==> acute or chronic disease
• Proteinuria and increased BP are common
• Histology: ranges from minimal change disease to crescenteric GN

Question 9

How does systemic sclerosis affect the kidneys?

Answer 9

• May affect the kidney in diffuse disease
  
  • Renal crisis presents with AKI and accelerated HTN
• ANCA associated vasculitis often involves the kidney ==> ESRD

Question 10

How does hyperparathyroidism affect the kidneys?

Answer 10

Hypercalcemia may cause nephrocalcinosis

Question 11

How does sarcoidosis affect the kidneys?

Answer 11

May involve the kidney, often by abnormal calcium metabolism (increased vitamin D metabolism by increasing calcitriol formation ==> hypercalcemia)