Kidneys in systemic disease Flashcards
How is a diagnosis of incipient diabetic nephropathy made?
The earliest evidence of diabetic renal disease is the appearance of microalbuminuria, i.e. low, but abnormal, amounts of albuminuria (≥30mg/day) • Patients with microalbuminuria are often said to have ‘incipient’ nephropathy.
How is overt diabetic nephropathy diagnosed (3 key things)?
DN (‘overt’ nephropathy) describes a clinical syndrome characterized by:
- Persistent albuminuria (>300mg/day) on at least two occasions, 3 months apart.
- ↑ BP.
- Progressive ↓ GFR.
How is hyperglycaemia related to diabetic nephropathy?
Stimulates mesangial cell matrix production and cell growth, leading to early glomerular enlargement.
Causes to advanced glycation end-product (AGE) formation:
- − AGEs result from non-enzymatic reaction between glucose and proteins.
- − They normally undergo renal excretion and accumulate as DN progresses, particularly in the circulation and the kidneys.
- − AGEs: (i) impair function of glycated proteins; (ii) cause abnormal cell-to-cell interactions through cross-link formation; (iii) bind endogenous receptors for AGEs (RAGE), with deleterious consequences.
How is diabetic nephropathy managed?
- Improving glycaemic control
- Improving blood pressure
- Improving diet and weight
4.
What is the pathophysiology of lupus nephritis?
Type III hypersensitivity reaction due to anti-nuclear antibodies depositing into the kidneys
What are the 4 key investigations in establishing lupus nephritis?
- Routine bloods- patients may have low serum albumin if they are nephrotic
- Autoimmune profile
- Renal USS
- Renal biopsy
What is the standard treatment for lupus nephritis?
- High dose prednisolone, MMf, cyclophosphamide
- Further maintenance of autoimmune remission with mycophenolate or rituximab
Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis includes what 3 conditions?
- granulomatosis with polyangiitis (GPA—previously known as Wegener’s granulomatosis),
- microscopic polyangiitis (MPA),
- renal-limited vasculitis (RLV).
How can a diagnosis of GPA be made in contrast to MPA?
GPA is differentiated pathologically by the presence of granulomatous inflammation, but this may not always be apparent if a biopsy for histological examination is not undertaken. Clinical surrogates that point towards GPA, rather than MPA, include upper airways symptoms or lower respiratory tract nodules and cavitation.
Compare the following factors in GPA vs MPA.
- ENT involvement
- ANCA specificity
- Granulomata
- Likelihood of relapse
- ENT involvement- GPA yes. MPA no.
- ANCA specificity. GPA c-ANCA. MPA p-ANCA
- Granulomata. GPA yes (not in kidney). MPA no.
- Likelihood of relapse. GPA yes. MPA no.
What are the systemic symptoms of vasculitis?
Systemic symptoms are common: fever, weight loss, malaise, myalgia, and polyarthralgia.
Give a validated score for vasculitis severity.
Birmingham vasculitis activity score (BVAS)
What is the treatment for ANCA associated vasculitis of the kidneys?
- Induction = typically achieved with 3 – 6 months of high dose Steroids + Cyclophosphamide / Rituximab. Plasma Exchange if presents with renal failure or pulmonary haemorrhage
- Maintenance = Azathioprine (1.5mg/kg) or low dose steroids
What is the main investigation for confirming ANCA associated vasculitis?
During testing for ANCA, the patient’s serum is tested for IgG binding to ethanol-fixed neutrophils.
- Binding occurs in either:
- A cytoplasmic pattern (c-ANCA) (antibody usually confirmed as anti-proteinase 3).
- A perinuclear pattern (p-ANCA) (antibody usually confirmed as anti-myeloperoxidase).
What is the pathophysiology of myeloma kidney?
Casts develop when the excess filtered load of light chains reacts with Tamm–Horsfall mucoprotein (THMP) in the more distal tubule and forms an insoluble proteinaceous plug. This obstructs tubular flow, disrupts tubular architecture, and leads to progressive interstitial injury (which becomes rapidly irreversible).
