Systemic Disease Affecting the Kidneys

Question 1

Explain the pathophysiology of diabetic nephropathy

Answer 1

Hyperglycaemia causes an increase in oncotic pressure which results in volume expansion. This causes intra-glomerular hypertension, hyperfiltration which leads to proteinuria and hypertension and renal failure

Question 2

Explain the presentation of diabetic nephropathy

Answer 2

• Usually occurs after **20 years **of disease,
• Always in association with other diabetic vascular abnormalities, especially retinopathy.
• Always presents with proteinuria
• Kidneys are normal size on US

Question 3

Explain the management od diabetic nephropathy

Answer 3

• Treaat hypertension with ACEi/ARB, low salt diet, weight loss and exercise.
• Improce blood glucose controle with education, drugs and technology (glucose sensors)
• SGLT-2 inhibitors, eg, empagliflozin

Always aim to prevent!

Question 4

Explain the pathogenesis of renal artery stenosis

Answer 4

• Progressive narrowing of renal arteries with atheroma
• When stenosis reaches 70% there is cortical hypoxia which causes microvascular damage and activation of inflammatory and oxidative pathways.
• Parencymal inflammation and fibrosis progress and become irreversible

Question 5

What is the management of renal artery stenosis?

Answer 5

• Medical management - Control BP (not with ACEi/ARBs as they increaase BP in glomerulus) and give statin.
• Lifestyle advice - Smoking cessation, exercise and low salt diet.
• Angioplasty - Done when there is uncontrolled BP on multiple agents, rapidly deteriorating renal function or flash pulmonary oedema

Question 6

What is the presentation of renal artery stenosis?

Answer 6

• Worsening renal function after starting ACE inhibitor,
  Asymmetrically sized kidneys
• Refractory hypertension
• Acutely can present with flash pulmonary oedema with no evidence of cardiac dysfunctio,
• Investgations: Renal angiography is gold standaard and renal USS shows small kidneys

Question 7

How can amyloidosis affect the kidneys

Answer 7

It can cause a nephrotic syndrome

Question 8

what are the two classess of amyloidosis and their association

Answer 8

AA - Systemic amyloidosis and is associated with inflammation/infection.
AL - immunoglobulin fragments from a haematological condition such as myelome

Question 9

What is the treatment of amyloidosis?

Answer 9

AA - treat underlying source of inflammation/infection.
AL - Treat underlying haematological condition
Consider referral to national amyloid centre

AL for myeLoma

Question 10

Explain the pathopysiology of lupus nephritis

Answer 10

• Autoantibodies produced against dsDNA or nucleosomes.
• Formation of intravascular immune complexes which can attach to the GBM
• Activation of complement (C4) occurs which causes damage to kidneys

Question 11

Explain the diagnosis and management of lupus nephritis

Answer 11

Renal biopsy to confirm diagnosis and stage.
Treat with immunosupopression (steroids, cyclophosphamide or hydroxychloroquine) and treat hypertension

Question 12

What is the classic triad of myeloma

Answer 12

Back pain, hypercalcaemia and anaemia

Question 13

Explain the pathogenesis of myloma renal disease

Answer 13

• Cast nephropathy (renal damage due to excess amount of light chains which causes damage to tubules)
• Hypercalcaemia which leads to dehydration
• Light chain deposition disease
• May have amyloid associated with myeloma
• May develop fanconi syndrome (antibody fragments are toxic to proximal tubule)

Question 14

What are renal casts and what are the different types?

Answer 14

Casts are clumped cells forming tubule shaped particles, they are seen microscopically.
Black/brown casts suggest acute tubular necrosis.
RBC casts suggest glomerulonephritis.
WBC casts may indicate acute interstitial nephritis