Renal Flashcards
How is AKI defined by KDIGO?
- increase in serum creatinine by >0.3mg/dL in 48hr
- increase in serum creatinine to >1.5x baseline, known or presumed to have occurred in the past 7 days
- urine output <0.5ml/kg/hr for six hours
How do KDIGO classify the stages of AKI?
- based on SCr or urine output (whichever is worst)
- stage 1: SCr 1.5-1.9x baseline or UO <0.5ml/kg/hr for 6-12 hours
- stage 2: SCr 2-2.9x baseline or UO <0.5ml/kg/hr for >12 hours
- stage 3: SCr >3x baseline or UO <0.3ml/kg/hr for 24 hours or anuria for >12 hours
What meds should be withheld is AKI is suspected?
- nephrotoxins
- hypotensives
- diuretics
(DAMN-AKI mnemonic) - diuretics
- ACEi / ARBs
- metformin
- NSAIDs
How can causes of AKI be classified?
- prerenal: decreased perfusion to the kidney
- intrinsic: renal disease
- postrenal: obstruction to the urine flow
How common is AKI?
- 18% of hospital patients
- up to ~50% of ICU patients
What are the risk factors for AKI?
- CKD
- age
- male sex
- comorbidities e.g.DM, CVD, malignancy liver disease)
What are the most common causes of AKI?
- Sepsis
- Major surgery
- Cardiogenic shock
- Other hypovolaemia
- Drugs
- Hepatorenal syndrome
- Obstruction
What are the key factors to manage in AKI?
- fluid balance
- acidosis
- hyperkalaemia
How would you manage hyperkalaemia in AKI?
1) calcium gluconate or calcium chloride IV until ECG normalises (cardioprotective because it stabilises the membrane but it doesn’t actually treat K+ level)
2) IV insulin in glucose OR salbutamol nebs
3) if underlying pathology cannot be corrected then renal replacement therapy may be indicated
In those with existing renal disease NSAIDs and ACEi can interact to cause an AKI, how does this happen?
- NSAIDs constrict the afferent arteriole
- ACEi dilate the efferent arteriole
- result is decreased filtration
How would you investigate a patient with AKI after they had been stabilised?
- urine dip (pre-catheter)
- USS KUB
- LFTs
- platelets plus a blood film if low
- specific tests for intrinsic renal disease if indicated (e.g. Igs, paraproteins, autoantibodies etc)
What stages form the immediate management of AKI?
Look for life threatening complications:
- examine: HR, BP, JVP, cap refill, palpate bladder - calculate NEWS
- pulmonary oedema?
- VBG for K+
Treat hypovolaemia:
- initial fluid challenge
- fluid management (consider catheter and hourly UO measurements)
Observations:
- every 4 hours as minimum
- more frequently if clinically indicated
Investigations:
- check K+ at least daily until creatinine falls
- daily creatinine until it decreases
- check lactate if signs of sepsis
Which drugs interfere with renal perfusion?
- ACEi
- ARBs
- NSAIDs
Which drugs require dose reduction or may be unsuitable for patients with renal disease?
All medications that are metabolised and excreted by the kidneys (~20% of meds, mainly water soluble ones) including:
- fractioned heparins
- opiates
- penicillin-based antibiotics
- sulphonylurea-based OHAs
- aciclovir
- metformin
Which drugs require closer monitoring in renal disease?
- warfarin
- aminoglycosides (e.g. gentamicin)
- lithium
Which drugs can aggravate hyperkalaemia?
- trimethoprim
- spironolactone
- amiloride
Do loading doses need dose adjustment in patients with renal disease?
Not usually, especially if it’s important to get to the therapeutic dose quickly
If a patient has renal disease, what figures should you use to calculate their dose adjustment?
- eGFR
- if unknown then assume <10ml/min/1.73m2
What are the potentially fatal complications of renal failure?
- hyperkalaemia
- pulmonary oedema
- intravascular volume depletion
- uraemic encephalopathy
- pericardial effusion
What are the functions of the kidney?
- elimination of waste products
- electrolyte homeostasis
- acid base balance
- fluid balance and BP control
- metabolism of vitamin D
- endocrine (EPO, vitD, RAAS)
What are the ECG signs that are indicative of hyperkalaemia?
- tall, tented T waves
- wide QRS
- sine wave pattern
What clinical methods can be used to assess intravascular volume?
- body weight
- skin turgor
- postural BP
- mucosal membrane hydration
- JVP
- lung base sounds
What are the main complications of CKD?
- anaemia
- renal bone disease
- acidosis
- hypertension
- malnutrition
- uraemia
What are the categories of CKD as classified by GFR?
>90 = G1 60-89 = G2 45-59 = G3a 30-44 = G3b 15-29 = G4 <15 = G5
What are the categories of CKD as classified by ACR?
<3 = A1 3-30 = A2 >30 = A3
What are the negative impacts of chronic dialysis on a patient?
- heavy time burden
- high morbidity of psychological illness
- limitation on travel
- diet restrictions
- complications can result in frequent hospital admissions
- home dialysis may require changes to the home and requires another person to be present during dialysis
What is the triad of nephrotic syndrome?
- proteinuria (>3g/day)
- hypoalbuminaemia
- oedema
- hypercholesterolaemia and hyperaldosteronism are secondary phenomena
What symptoms form nephritic syndrome?
- haematuria
- proteinuria
- mild hypertension
- reduced urine output (<300ml/day)
What investigations can show proteinuria? Which are preferred?
- dipstick
- albumin/creatinine ratio (preferred screening test)
- protein/creatinine ratio (used for monitoring proteinuria in patients with established proteinuria)
What are the potential consequences of loss of function of the glomerular basement membrane?
- protein loss
- blood loss
What are the most common causes of nephrotic syndrome in children?
- minimal change glomerulonephritis
2. focal segmental glomerulosclerosis
What are the most common causes of nephrotic syndrome in adults?
- membranous glomerulonephritis
- IgA nephropathy
- Diabetic nephropathy
- SLE
- Amyloidosis
Describe minimal change glomerulonephritis
- patient has nephrotic syndrome
- light microscopy would show all normal glomeruli
- electron microscopy would show fusion of podocyte foot processes and therefore loss of the filtration barrier
What is the initial management for a child with nephrotic syndrome? Why?
- steroid treatment without a biopsy
- most children would have minimal change GN on histological sample
- most minimal change GN responds to steroids
- diagnosis is clinical and dependent on response as there is no histological diagnosis (steroid responsive nephrotic syndrome // relapsing nephrotic syndrome // steroid dependent nephrotic syndrome // steroid resistant nephrotic syndrome
What is the next step in management for a child diagnosed with steroid resistant nephrotic syndrome?
- biopsy (likely inherited podocyte protein abnormality or other cause of GN e.g. FSGS
What is the prognosis for membranous glomerulonephritis in adults?
- 1/3 spontaneous recovery
- 1/3 persistent proteinuria
- 1/3 progress to end stage renal failure (ESRF)
What is the most common cause of membranous glomerulonephritis?
- autoimmune response
What underlying diseases may be associated with membranous glomerulonephritis?
- adenocarcinoma (lung or GI)
- hepB
- SLE (Class V lupus nephritis)
The use of which drugs have been associated with membranous glomerulonephritis?
- gold/penacillamine
What kind of treatment may be helpful in membranous glomerulonephritis?
- immunosuppressants
How is IgA nephropathy diagnosed?
- biopsy with fluorescent anti-IgA staining of biopsy specimen
What is the classical presentation of IgA nephropathy?
- visible haematuria
- 1 to 2 days after URTI
- in younger patients
What factors worsen the prognosis of IgA nephropathy?
- proteinuria
- hypertension
- scarring on biopsy
- male
- abnormal renal function
What is the prognosis for patients with IgA nephropathy?
- very variable
- can be relatively benign
- 36% of patients progress to end stage renal failure or death within 20 years
What is Alport’s syndrome?
- genetic disorder affecting Type IV collagen
- can be x-linked so severity in men > women
- generally presents in childhood with: haematuria, proteinuria, progressive renal failure, sensorineural deafness, anterior lenticonus
What are the common causes of nephritic syndrome in children?
- haemolytic uraemia syndrome
- henoch-schonlein purpura
- post-streptococcal glomerulonephritis (most common)
What are the common causes of nephritic syndrome in adults?
- Goodpasture’s*
- ANCA-associated vasculitis*
- SLE
- primary or secondary mesangiocapillary glomerulonephritis
*most common
Describe the typical presentation, histology, management and prognosis of post-streptococcal glomerulonephritis
- haematuria 10-14 days post streptococcal throat infection
- diffuse, global, proliferative glomerulonephritis
- supportive care
- spontaneous recovery
Describe the typical presentation, histology, serology, management and prognosis of rapidly progressive glomerulonephritis
- AKI (days to weeks)
- crescentic glomerulonephritis and vascular necrosis
- antineutrophil cytoplasmic antibodies (ANCA): two forms cANCA and pANCA
- steroids/cyclophosphamide +/- plasma exchange
- rituximab may also be used
- early treatment = better outcome
What is the eponymous name for antiglomerular basement membrane antibody disease?
Goodpasture’s
Describe the typical presentation, histology, serology, management and prognosis of antiglomerular basement membrane antibody disease
- AKI +/- pulmonary haemorrhage
- crescentic glomerulonephritis, linear IgG deposition along basement membrane
- anti-GBM antibody +ve
- treat with steroids / cyclophosphamide / plasma exchange
- early treatment = better outcome
What is another name for mesangiocapillary glomerulonephritis?
- membranoproliferative glomerulonephritis
Give examples of causes of mesangiocapillary glomerulonephritis
- infection
- collagen vascular disease
- monoclonal gammopathies
- genetic and acquired complement disorders
What is the eponymous name for the amorphous histological features in the glomerulus, common in diabetic nephropathy?
- Kimmelsteil-Wilson lesions
What histological stain would confirm a diagnosis of glomerular amyloidosis?
- congo red stain
What diseases commonly underlie AA amyloidosis?
- chronic inflammatory conditions e.g. RA, Crohn’s, ankylosing spondylitis
- chronis pyogenic infections e.g. bronchiectasis, osteomyelitis
What is AA amyloidosis also known as?
- secondary amyloidosis
What is primary amyloidosis associated with?
- AL amyloid
- multiple causes e.g. myeloma, lymphoma
- 90% of patients have paraprotein in blood or urine
Which organs are predominantly affected by AA amyloidosis and AL amyloidosis?
- AA = kidneys
- AL = kidneys and heart
Pros of kidney transplant?
- removes or alleviates burden of dialysis
- improves renal clearance (dialysis GFR usually only ~10ml/min)
- restores endocrine functions of kidney (e.g. EPO production, hydroxylation of vitD)
- improves patient life expectancy (if patients are appropriately selected)
Cons of kidney transplant?
- significant peri-operative mortality risk: ~2% but higher with comorbidity (particularly due to cardiovascular risk and sepsis)
- lifelong burden of immunosuppression (risk of infections, risk of cancers (esp non melanoma skin ca, cervical ca, lymphoma), risk of new-onset post-transplant diabetes = 12-20%)
What are the contraindications for renal transplant?
- active infection
- active cancer
- short life expectancy due to other conditions
- circumstances which are likely to make post-transplant care challenging e.g. previous non-compliance with follow-up/treatment, active drug ‘misuse’, uncontrolled major psychiatric disorders, chaotic lifestyle including homelessness or frequent moves out of area
What are the sources of kidney transplants?
Cadaveric donor:
- deceased, brain dead (DBD)
- deceased, cardiac death (DCD)
Living donor:
- related e.g. blood relative, spouse, friend, colleague
- unrelated e.g. paired/pooled system match, altruistic donor
What’s the average waiting list time for kidney transplantation?
2.5 years
Which transplant immunosuppressants act on Calcineurin?
- tacrolimus
- cyclosporine A
Which transplant immunosuppressants inhibit de novo purine synthesis?
- azathioprine
- mycophenolate
Which transplant immunosuppressant targets mTOR?
- sirolimus (rapamycin)
What is the target of the Daclizumab?
- IL-2R
Which complex presents alloantigens from APCs to T cells?
MHC II
What is the role of Calcineurin in T cell activation?
- dephosphorylates NFAT
- complexes with NFAT and translocates to the nucleus
- unregulated transcription of pro-inflammatory cytokines including IL-2