Nephro: The Kidney in Systemic Disease Flashcards
why is renal involvement relevant in systemic disease?
- there is a worse prognosis if the kidneys are involved
- different treatment is needed if the kidneys are involved
- rarely the nature of systemic disease is only established by a renal biopsy
when should you suspect renal involvement in systemic disease?
- evidence of renal disease
- evidence of systemic disease
- both of the above have to correlate with each other
what is the most obvious abnormality in multiple myeloma
diminished renal function
indicators of renal disease
- abnormal renal function
- abnormal urinalysis (IMP)
- abnormal renal imaging
how is the renal structure in AKI?
renal size and anatomy are preserved
what happens if systemic disease equally affects both kidneys
use functional imaging like IVU, CT with contrast and DTPA scan
- can also be detected by blood tests
what renal test is always significant
a drop in eGFR (disease can also be present in a normal eGFR)
how does the eGFR vary between genders
females have a eGFR which is 15% less than in men
what can urinalysis show?
haematuria and proteinuria
what does urine microscopy show?
casts
what types of casts can be found on microscopy?
granular and hyaline casts may mean nothing
cellular casts are always bad
how do you quantify proteinuria?
- simple urinalysis
- ACR
- 24h urine collection
what is the dipstick sensitive to?
albumin
what does albuminuria indicate?
glomerular pathology
what will kidneys damaged by multiple myeloma show
- negative dipstick
- normal ACR
- elevated PCR
important things to get from a history
- other comorbidities
- symptoms related to multisystem disorders
- underlying malignancy
- is the patient at risk of being HepB, HepC or HIV positive?
what are features that suggest diabetic nephropathy?
- nephrotic-range proteinuria
- time between diagnosis of DM and DN is more than 5 years
- evidence of microvascular disease elsewhere like in the eyes and NS
- the condition is progressing at a slow rate
what does haematuria in a diabetic mean?
means that there is another renal problem apart from the DN
when would you do a renal biopsy?
when there are signs which are not linked with DN such as haematuria, cellular casts, rapid progression in disease or serological tests suggesting other systemic disease
risk factors for nephrosclerosis
- age
- HTN
- diabetes
examples of connective tissue disorders that affect the kidneys
- SLE
- RA
- mixed CT disease
examples of primary vasculitides that affect the kidneys
- microscopic polyangiitis
- wegeners granulomatosis
- churg strauss syndrome
- Henoch-Schonlein purpura
others disease that effect the kidneys
- Goodpasteur’s disease
- subacute bacterial endocarditis
- mixed essential cryoglobulinaemia
what are these systemic diseases with renal involvement have in common
- glomerular involvement
- presence of cellular casts
- rapidly progressive disease
- microscopic haematuria
what does a glomerulonephritis screen include?
- ANA, anti-ds DNA, RF, ENA
- complements
- ANCA, anti-MPO, anti-PR3
- HBsAg and HepC antibodies
- Anti-GBM
which tests are positive in connective tissue disorders?
ANA, anti-ds DNA, RF, ENA
when is there hypocomplementaemia
- lupus nephritis
- bacterial endocarditis
- mixed essential cryoglobulinaemia
when is Anti-GBM positive??
in Goodpasture’s syndrome
what heart conditions are associated with SLE?
- endocarditis
- chordae tendinae rupture
- mitral regurgitation
what is the first sign of lupus?
butterfly rash
what is the classification of lupus nephritis
I: minimal mesangial LN II: mesangioproliferative LN III: focal proliferative LN IV: diffuse proliferative LN V: membranous LN VI: advanced sclerosing LN
from which stage of lupus nephritis is the capillary wall being involved?
Stage 3 onwards
in which stages of LN are there mesangial deposits?
Stage I and II
in which stages of LN are there subendothelial deposits?
Stage III and IV
in which stage is there subepithelial deposits?
Stage V
when would you treat with glucocorticoids?
Stage II onwards
what are additional drugs that can be used to treat LN
- mycophenolate mofetil
- cyclophosphamide
- rituximab
- cyclosporin
- tacrolimus
investigations for multiple myeloma
- ESR
- CBC
- SPE
- urinary protein electrophoresis
- free light chain assay (serum and urine)
- bone marrow aspirate
- skeletal survery/MRI
effects of multiple myeloma on the kidney
- decreased renal perfusion
- hyperuricaemia
- direct complications of monoclonal light chains
- plasma cell infiltration
why is the uric acid level high?
it is crystallised within the tubules, causing obstructive uropathy
what do the monoclonal light chains cause in the kidney?
- myeloma cast nephropathy
- light chain deposition disease
- AL amyloidosis
- croglobulinaemia
- membranoproliferative glomerulonephritis
- heavy chain deposition disease
what is the commonest cause of renal impairment in multiple myeloma
myeloma cast nephropathy
investigations in myeloma cast nephropathy
- urine dipstick (albuminuria is negative but no light chains)
- Bence-Jones proteins in urine
- aggregation of light chains with Tamm-Horsfall protein
- drop in eGFR (due to the blockage)
what can the light chain fragments be converted to?
beta pleated sheets, forming amyloidosis
how can amyloidosis be detected?
congo red positive glomerular deposits
what happens if the fragments cannot form beta pleated sheets?
they deposit in the kidney, causing light chain deposition disease (negative in congo red stain)
what do light chain deposition disease and amyloidosis have in common?
- nephrotic proteinuria
- renal impairment
