AKI Flashcards
Define AKI criteria
Rise in serum creatinine of 26 micro mol/L or greater within 48 hours
50% of greater rise in serum creatinine within past 7 days
Fall in urine output to <0.5 ml/kg/hour for more than 6 hours
Is creatinine or eGFR better for measuring AKI and why
Creatinine since it exclusively excreted by the kidneys
eGFR better for CKD
Urea also measured for AKI
Risk factors of AKI
Over 65y
History of AKI / CKD with GFR <60
Urinary obstruction symptoms
Heart failure
Liver disease
Diabetes
HTN
Neurological/cognitive impairment e.g. Stroke
Sepsis
Exposure to nephrotoxins / iodinated contrast agents
Perioperative
AKI signs and symptoms presentation
Reduced urine output - oligouria
Change in urine (frothy - proteinuria, dark, haematuria)
Possible dysuria
Signs of underlying cause - sepsis (pyrexia), rash from vasculitis
Signs of raised urea - Confusion/drowsiness, n+v, pruritis, fatigue
Fluid overload / Hypovolaemia signs - oedema and hypertension
Signs
- rapid rise in serum creatinine and urea
Name nephrotoxins
NSAIDs / COX2is
ACEi / ARB
Thiazide/loop diuretics
Potassium sparing diuretics
Metformin
Trimethoprim association with AKI
Trimethoprim is an antibiotic used for UTI
Interferes with creatinine secretion from tubules into urine - high creatinine may not be from AKI!!
How do you know raised creatinine is from AKI and not from CKD
If creatinine raise over a day or week is consistent with CKD instead of acute raise, it’s CKD
Pregnancy association with AKI
Creatinine may be raised post pregnancy and doesn’t mean AKI
What are the 3 different volume statuses
Dehydration/ hypovolaemia
Uraemia
Hypervolaemia
Components that can be checked in fluid balance assessment
Blood pressure
Urine output
Oedema - sacrum/peripheral
JVP
What are the 3 categories of AKI
Pre renal
Intra renal (intrinsic)
Post renal
Mechanism of pre renal AKI
Decreased renal perfusion
- shock (hypovolaemic, cardiac, distributive)
- decreased circulating volume e.g. dehydration
- decreased cardiac output e.g. cardiac failure
- liver failure / cirrhosis
- systemic vasodilation e.g. sepsis, hypotension
- arteriolar changes in the glomeruli e.g. from ACEi, ARBs or NSAID use
- renovascular disease (renal artery stenosis) - more likely for CKD though
Causes of Hypovolaemia
Haemorrhage
Diuresis
GI loss (vomitting, diarrhoea)
Skin - sweating/burns
Reduced water intake / electrolyte intake
Medications
AKI characterisation
Increased creatinine and urea with oligouria (abnormally reduced urine output)
Renal artery stenosis presentation and clinical signs
Accelerated and difficult to control HTN
AKI post ACEi/ARB initiation
Progressive CKD
EPISODES OF FLASH PULMONARY OEDEMA
- bruit on abdominal examination
- narrowing on renal artery MRI with angiography
Diagnostic investigation for Renal artery stenosis
Renal arteriography
- can do CT or MRI though
Indications for acute dialysis
AEIOU
A - acidosis (pH under 7.2)
E - electrolyte imbalance (resistant hyperkalaemia)
I - intoxication (drug overdose, poisoning)
O - oedema
U - uraemia
What is Intra renal AKI
AKI caused by intrinsic renal pathology (damage or dysfunction to glomerulus, bowman’s capsule, and or tubules)
What is rhabdomyolysis
Skeletal muscle injury causing rapid breakdown and necrosis of skeletal muscle releases metabolic products e.g. myoglobin and potassium directly into blood
Causes of rhabdomyolysis
Trauma - elderly fall leading to prolonged immobilisation (anaerobic conditions for muscles leading to breakdown), crush injuries, burns, seizures, compartment syndrome
Ischaemia related to- embolism, surgery
Toxin induced - medications (statins, vibrates, neuroleptics), recreational drugs (ecstasy)
Strenuous / extreme physical activity e.g. intense spin class
What type of kidney issue can rhabdomyolysis lead to and why
Intra renal Acute kidney injury - metabolic products from skeletal muscle breakdown (myoglobin and potassium) damage glomeruli
Rhabdomyolysis symptoms
Muscle pain and swelling
Red / brown urinary - TEA OR COLA COLOURED - due to myoglobinuria
AKI occurs 10-12 hours after initial injury or pain onset
Rhabdomyolysis clinical signs and investigations
SERUM CREATININE FIVE FOLD RAISE FROM UPPER LIMIT - due to muscle breakdown
Raised lactate dehydrogenase
Hyperkalaemia, hyperphosphataemia, hyperuraemia, hypercalcaemia
Positive urine dipstick for blood due to myoglobinuria with no red blood cells on microscopy
Rhabdomyolysis treatment and management
Supportive management with IV fluid to excrete myoglobin and monitor electrolytes
treat hyperkalaemia - if not managed may need emergency dialysis (due to risk of acute renal failure)
What type of condition is nephritic and nephrotic syndromes?
Intra renal AKI
List nephritic syndrome conditions
IgA nephropathy - Berger’s disease - type of glomerulonephritis
Post infectious glomerulonephritis
Vasculitis
Lupus nephritis
Infective endocarditis driven immune complex mediated
Typical presentation of nephritic syndrome
Sudden onset - pt acutely unwell
Some oedema
RAISED BP
some proteinuria and hypoalbuminaemia
HAEMATURIA - cola coloured
Oligouria
May or may not hypercholesterolemia
Typical presentation of nephrotic syndrome
Gradual onset - pt more acutely well
OEDEMA
PROTEINURIA
HYPOALBUMINAEMIA
may or may not have haematuria
HYPERCHOLESTEROLEMIA
What are the differences in nephritic and nephrotic syndrome presentations !!!
Nephritic - sudden onset so pt acutely unwell, RAISED BP, not much oedema, only some proteinuria and hypoalbuminaemia, lots of haematuria, may not have hypercholesterolemia
Nephrotic - gradual onset so pt acutely well, lots of OEDEMA, NORMAL blood pressure, lots of PROTEINURIA and hypoalbuminaemia, HYPERCHOLESTEROLEMIA
Nephritic syndrome mechanism
Endothelial wall of Glomerular capillary wall damage from immune complex formation - sediments seen on microscopy
IMMUNE SYSTEM MEDIATED
Investigations for nephritic syndrome
Urine dip for leukocytes (due to immune relation) proteins and blood
Urine protein creatininratio (PCR)
Acute renal screen
Management of nephritic syndrome
Urgent renal referral
BP control - may have diuresis
Treatment for underlying infection after confirming on microscopy / renal biopsy
What is IgA nepropathy and its mechanism
Most common type of glomerulonephritis (nephritic syndrome - Intra renal AKI)
- glomerular deposits of immunoglobulin A lodges in glomerulus, IgA activates complement pathway and cytokines release
- this all leads to glomerular injury
IgA nephropathy presentation
Recurrent / episodic haematuria
Teen - thirties
Common after URTI, resp or gastrointestinal infection
Hypertension
Mild proteinuria
IgA nephropathy investigations
Urinalysis - blood and protein
Microscopy - dysmorphic red blood cells showing glomerular damage
Urgent referral to renal
Gold standard - renal biopsy
Serum IgA raised in 50% of pts
IgA nephropathy management
Supportive management - salt restriction, hypertension management, proteinuria management (ACEi and ARB)
What is post infectious glomerulonephritis
Nephritic syndrome - Intra renal AKI
Immune complex mediated glomerulonephritis
Presentation of post infectious glomerulonephritis
Children
Sudden onset of haematuria 1-3 weeks after group A streptococci infection (URTI, throat or skin infection, infective endocarditis)
Oedema 1-3 weeks after infection
Hypertension
Post infectious glomerulonephritis investigations
Urinalysis - for blood, maybe protein
Microscopy - dysmorphic red blood cells (sign of glomerular / renal bleeding)
FBC - resided WBC due to infection
Urea and electrolytes- sign of AKI
Gold standard - renal biopsy - humps
What is vasculitis
Auto immune condition - nephritic syndrome - inflammation of small blood vessels and immune cell infiltration causing vessel wall damage e.g. haemorrhage / aneurysm or vessel occlusion
Vasculitis presentation
65-74
Systemic symptoms - weight loss, fevers, malaise, polyathralgia (pain in several joints)
Depending on which blood vessels affected - in lungs (haemoptysis, pulmonary haemorrhages), ENT (epistaxis, sinusitis), eyes (conjunctivitis, episcelritis), cardiac (myocarditis)
RENAL (HAEMATOPROTEINURIA, HYPERTENSION, PROGRESSIVE AKI)
ANCA associated
Vasculitis management
Urgent same day referral for biopsy
Immunosuppression depending on severity and frailty
Triad for diagnosing nephrotic syndrome
Fluid overload
Low albumin
Heavy proteinuria
What is nephrotic syndrome
Glomerular protein leakage - increased permeability to serum proteins in glomerulus due to damaged basement membrane
Presentation of nephrotic syndrome (symptoms and clinical signs)
Frothy urine - proteinuria
Oedema
Signs
Hypoalbuminaemia
HYPERLIPIDAEMIA (hypercholesterolemia)
Lipiduria
Pro-thrombotic tendency - venous thrombosis - blood clots
Causes of nephrotic syndrome
Lupus
Amyloid
Minimal change disease
Membranous nephropathy
Investigation and management of nephrotic syndrome
Ix
Urine dipstick - protein
Urinalysis- albumin creative ratio raised
Renal biopsy , acute renal screen to find cause
Tx
High dose corticosteroids
Reduce proteinuria - ACEi and ARBs - proteinuria is risk factor for progression to CKD
Depends on cause and symptoms - immunosuppression for lupus, BP management, diuresis for fluid overload/oedema
prophylaxis for VTE
Multiple myeloma investigations
Bone profile - calcium levels
FBC - anaemia and low platelets
CT skeleton
Serum protein electrophoresis
Serum free light chains
Multiple myeloma treatment
IV hydration and correcti9n of hypercalcaemia
Haematology referral
Bone marrow biopsy
Chemotherapy + dexamethasone
What is multiple myeloma and how does it cause kidney damage
Bone marrow cancer
Hypercalcaemia and light chain deposition in glomerulus causes renal damage - Intra renal AKI
Lupus nephritis presentation + clinical signs
More often in women
Afro-Caribbean and Asian predisposed
Young adulthood
Weight loss, fever, rash, Alopecia, pericarditis, headache, seizure, stroke, thrombocytopenia, athralgia, arthritis
Clinical signs
- proteinuria (due to autoimmune complex formation and deposition)
Low grade haematuria
Low albumin and raised PCR
Raised ESR!!!
Positive ANA
What is obstructive uropathy
Type of post renal AKI
Obstruction increases Intra tract pressure as urine builds up causing hydronephrosis
What is hydronephrosis
Swelling and inflammation of obstructed kidney
When does obstructive uropathy lead to renal failure
Only present of single functioning kidney or is obstruction is bilateral (obstruction may be in bladder and below)
What are the 3 classifications of obstructive uropathy
Level of obstruction (upper is ureter and above so more likely unilateral , lower is bladder and below so more likely bilateral)
Complete or partial obstruction (urine output varies in partial but complete causes ANURIA)
Intrinsic or extrinsic (intrinsic cause within tract like stones, extrinsic cause outside of tract like BPH or ovarian mass)
Symptoms and clinical signs of obstructive uropathy
Pain (flank pain)
Haematuria
Changes to urine volume
ANURIA!!!
Dysuria
Clinical findings
Palpable bladder (full or urine) - dull on percussion
Loin tenderness
Flank mass - rare
Obstructive uropathy investigations
Urine MCS and urine dipstick
Creatinine (may be normal if one kidney normal and compensating during unilateral obstruction)
CRP, WBC and blood cultures
PSA for men with lower urinary tract symptoms
Ultrasound- - appearance may be delayed
Obstructive uropathy treatment - done by urology / renal team
Relieve obstruction - catheter
- nephrostomy (if site of obstruction is further up then stent and block)
Manage underlying cause
Antibiotics due to stasis of urine
What is reflux nephropathy
Reflux of urine up ureters as bladder contracts during micturition
Complicati9ns of reflux nephropathy
UTIs
Tubules scarring / atrophy
If not resolved into adulthood will present as CKD / proteinuria
Reflux nephropathy presentation
Childhood most commonly due to abnormally developed urinary tract - becomes better when developed
Prolonged bed wetting
Frequent UTIs!!! - leukocytes and nitrates may be present on investigations
Resolves in adulthood after urinary tract development or if not may present as CKD or unexplained proteinuria
What is pyelonephritis
Acute infection of ascending urinary tract and kidney
Diagnosis of pyelonephritis
Clinical diagnosis
Only US if other symptoms e.g. incomplete bladder emptying, obstruction, stones , abscess
Pyelonephritis treatment
Urine MCS and Blood cultures then start antibiotics
Manage AKI
Indications for emergency dialysis
Acidosis despite management
Electrolytes - hyperkalaemia despite management
Intoxication - drugs
Overload - pulmonary oedema - remove extra fluid
Uraemia - pt may be confused / drowsy
