Renal Flashcards
Functions of the kidney (7)
Regulation of blood volume Regulation of blood pressure Acid-base balance Electrolyte balance Production of Red blood cells Synthesis of Vitamin D – Bone metabolism Excretion of water-soluble waste products – Filter
Define AKI
“A rapid decline in renal function over hours or days”
How is AKI measured
Urea and creatinine
Easiest way to recognise AKI
You stop peeing
Main three ways AKI causes problems and what are they
Fluid oliguria, volume overload
Electrolyte hyperkalaemia
Acid-base metabolic acidosis
Define CKD
Impaired renal function for >3 months based on
abnormal structure or function, or
GFR <60ml/min for >3m
+/- evidence of kidney damage
What is used to risk stratify AKI
KDIGO
Signs of AKI (5)
Hypertension
Distended bladder
Dehydration - postural hypotension
Fluid overload (in heart failure, cirrhosis, nephrotic syndrome) - raised JVP, pulmonary and peripheral oedema
Pallor, rash, bruising (vascular disease)
Main 4 symptoms of AKI
Oliguria/anuria NOTE: abrupt anuria suggests post-renal obstruction Nausea/vomiting Dehydration Confusion
What is the pathological mechanism behind pre-renal AKI
Inadequate Perfusion
What are the 4 mechanisms that can cause prerenal AKI
Hypovolaemia
Systemic vasodilation
Decreased cardiac output
Intrarenal vasoconstriction
What can cause hypovolaemic AKI (7)
Renal loss from diuretic overuse, osmotic diuresis (e.g., diabetic ketoacidosis)
Extrarenal loss from vomiting, diarrhea*, burns, sweating, blood loss
What can cause systemic vasodilatory AKI (2)
Sepsis*, neurogenic shock
What can cause decreased CO AKI (2)
HF, MI
What can cause intrarenal vasoconstrictive AKI (3)
Cardiorenal syndrome, hepatorenal syndrome
ACEi with renal artery stenosis
What are the four main mechanisms behind renal AKI
Acute tubular necrosis
Glomerulonephritis
Interstitial nephritis
Vascular obstruction
What can cause renal AKI through acute tubular necrosis (3)
Ischemia, drugs, toxins (paracetamol, NSAIDs, ACE-I, contrast, myoglobinuria in rhabdomyolysis etc.)
Which drugs can cause renal AKI through acute tubular necrosis (3)
paracetamol, NSAIDs, ACE-I,
Which toxins can cause renal AKI through acute tubular necrosis (2)
contrast, myoglobinuria in rhabdomyolysi
Main way of getting glomerulonephritis?
Postinfectious
What can cause renal AKI through interstitial nephritis (3)
Drugs
Infection
Infiltration
What can cause renal AKI through vessel obstruction (3 (+3))
Thrombosis
vasculitis
haemolytic microangiopathy (HUS, TTP, DIC)
What are the 3 main mechanisms behind post-renal AKI
Luminal
Mural
Extrinsic compression
What can cause luminal post-renal AKI (2)
Stones, clots
What can cause mural post-renal AKI (3)
Malignancy (e.g. uteric, prostate, bladder), BPH,
strictures
What can cause extrinsic compression post-renal AKI
Retroperitoneal fibrosis
HUS is a microangiopathy characterised by what 3 things
Progressive renal failure - Kidneys
Microangiopathic haemolytic anaemia (MAHA) – Blood
↓ Platelets - Blood (thrombocytopenia)
Most common cause of HUS
E. coli O157:H7
Pathophysiology of HUS
Gastroenteritis (E.coli 90%) toxin
Endothelial damage
Thrombosis, platelet consumption + fibrin strand deposition → ↓ Platelets
Destruction of RBCs – schistocytes, ↓ Hb
Ix for HUS
Raised urea and creatinine
Haematuria and proteinuria
Pain and bloody diarrhoea
Low Hb and platelets
What is the pentad of TTP
Haemolytic anaemia Thrombocytopenia Uraemia Fever Neurological symptoms
What neurological features can you get in TTP (4)
Seizures
Hemiparesis
↓ consciousness
↓ vision
What is the pathology behind TTP
Deficiency of protease (ADAMTS13) that cleaves cleave vWF
Large vWF multimers form
Platelet aggregation & fibrin deposition
Microthrombi
Typical population of TTP patients
Females between 10-50
Ix for glomerulonephritis (5)
BP: normal to malignant HTN
Urine dipstick: protein, blood
Renal function (urea and creatinine)
2 main mechanisms behind glomerulonephritis
Loss of barrier function - proteinuria and haematuria
Loss of filtering capacity - reduced toxin excretion
Common primary causes of nephritic glomerulonephritis (and which is the most common) (4)
IgA nephropathy (most common)
Henoch Schonlein purpura
Post-streptococcal GN
anti-GBM disease (Goodpasture’s disease)
Common primary causes of nephrotic glomerulonephritis (2)
Minimal change disease
Membranous nephropathy
Focal segmental glomerulosclerosis
Membranoproliferative glomerulonephritis
What is the triad in nephrotic syndrome
The nephrotic syndrome is a triad of:
• proteinuria >3g/24h (P:CR >300mg/mmol, A:CR >250mg/mmol, p294)
• hypoalbuminaemia (usually <30g/L, can be <10g/L)
• oedema.
What is the triad in nephritic syndrome
Hypertension + Haematuria + Oedema (+ Oligouria <400mL/day
What is the main cause of proteinuria
Injury to podocytes
What do red cell casts prove
Leakage is from the glomerulus
Common secondary causes of nephrotic syndrome (5)
Diabetes
SLE
Amyloid
HBV/HCV
Common secondary causes of nephritic syndrome (5)
Post streptococcal Vasculitis SLE Anti-GBM disease Cryoglobulinaemia
What is a common cause of glomerulonephritis in children
Minimal change disease
Presentation (2) and what happens in IgA nephropathy
Days after URTI infection
↑IgA immune complex formation
Episodic haematuria
Presentation (5) and what happens in IgA nephropathy
Haematuria
Purpuric rash extensor surfaces
Polyarthritis, Scrotal swelling , Abdo pain
Systemic variant IgA nephropathy
Presentation (2) and what happens in anti-GBM disease
Haematuria
Haemoptysis
Auto-Ab to Type IV collagen (GBM & lung)
Post streptococcal GN
Presentation (4)
What happens
1-12w after throat /skin infection: Strep Ag deposited glomerulus > immune complex formation
Nephritic syndrome: - consist of a TRIAD of
Hypertension + Haematuria + Oedema (+ Oligouria <400mL/day)
What is the most common cause of glomerulonephritis
Pauci-immune
Which antibody is associated with Pauci-immune
ANCA with negative immunofluorescence
Mx of glomerulonephritis (50
Refer specialist BP management – <130/80 ACE-I or ARB – reduce proteinuria and preserve renal function Steroids/immunosuppression Treat underlying cause
Ix for glomerulonephritis (6)
Bloods – FBC, U&Es, CRP, Complement, Autoantibodies
Urine MCS
Imaging - renal US/biopsy
What is the most common cause of renal AKI
Tubular necrosis
What can cause ischaemic tubular necrosis (6)
Hypovolaemia (haemorrhage/volume depletion/GI bleed/burns….etc)
Low CO
Systemic vasodilation – sepsis
DIC
Renal vasoconstriction
Impaired renal autoregulatory responses e.g COX inhibitors, ACE-I, ARBS
What are the endogenous nephrotoxins (4)
myoglobinaemia (rhabdomyolysis), haemaglobinuria, crystals, myeloma
What are the common exogenous nephrotoxins (3)
NSAIDs, cisplatin, aminoglycosides – gentamicin, streptomycin
Contrast agents
Anaesthetic agents
3 phases of ischaemic acute tubular necrosis
INITIATION –acute ↓ GFR + ↑ Cr + ↑urea
MAINTENANCE – sustained ↓ GFR (~1-2w) Cr + urea ↑
RECOVERY – tubular function regenerates ↑urine volume + gradual ↓ urea + Cr
Define myeloma
Malignant disease of bone marrow plasma cells which results in a clonal expansion of plasma cells - monoclonal paraprotein production
Features of myeloma (4)
Calcium – HIGH
Renal failure (acute or chronic) - ↑ urea ↑ Cr
Why? Hypercalcaemia, paraprotein deposition
Anaemia
Bone – osteolytic bone lesions – pain, fracture (risk cord compression)
Symptoms of rhabdomyolysis
Muscle pain and swelling, dark urine (myoglobin)
Ix for rhabdomyolysis (2)
Hyperkalaemia, High CK
Causes of interstitial nephritis (5)
Drugs Infections Immune disorders e.g. SLE Lymphoma Tumor lysis syndrome following chemo
What is the earliest sign of kidney damage in DM
detection of albumin in urine (elevated albumin:creatine ratio)
Complications of AKI (6)
Uraemia Volume overload - oedema Hyperkalaemia Hyperphosphataemia Metabolic Acidosis Chronic progressive kidney disease
What is the most common cause of nephrotic syndrome in adults
Membranous glomerulonephritis
Define CKD
Progressive loss of kidney function over a period of months or years
Impaired renal function for >3 months based on abnormal structure or function
Causes of CKD (6)
Diabetes Hypertension Atherosclerosis Chronic glomerulonephritis Infective or obstructive uropathy Adult polycystic kidney disease (APKD) is the commonest inherited cause of CKD
RF of CKD (8)
DM, HTN, CVD, Structural renal disease, multisystem disorders involving kidney, FHx, recurrent UTI, vesicoureteric reflux
Symptoms of severe CKD (9)
Anorexia Nausea and vomiting Fatigue Pruritus Peripheral oedema Muscle cramps Pulmonary oedema Sexual dysfunction is common
Main 5 consequences of CKD
- Progressive failure of homeostatic function
- Progressive failure of hormonal function
- Cardiovascular disease
- Uraemia and Death
What does progressive failure of homeostatic function in CKD lead to (2)
- Acidosis
- Hyperkalaemia
What does progressive failure of hormonal function in CKD lead to (3)
- Anaemia
- Renal Bone Disease - Osteomalacia
What does progressive failure of CVD in CKD lead to (2)
Vascular calcification
-Uraemic cardiomyopathy
What happens in renal osteodystrophy
Kidneys cant convert vitamin D3 into calcitriol = hypocalcaemia
Leads to secondary hyperparathyroidism
PTH stimulates bone resorption
Poor quality bones= osteomalacia: pain, fractures
Insufficient mineralization of bone osteoid
What do you test for in the bloods of suspected CKD (8)
↓Hb (normocytic anaemia); U&Es (↑urea/Cr), glucose (DM), eGFR, ↓Ca2+, ↑PO43−, ↑ALP (in renal osteodystrophy) ↑PTH if severe CKD
Ix for CKD not bloods (5)
Urine: dipstick, MC&S, Protein:Cr ratio
Imaging: USS to check size/anatomy/cortico-medullarly differentiation and eliminate obstruction – in CKD kidneys are small (<9cm) but may be enlarged in infiltrative disorders
CXR: Pericardial effusion or pulmonary oedema
Histology: consisted renal biopsy if rapidly progressing or unclear cause (C/I for small kidneys
BP target in CKD and for diabetics
target <130/80 ( <125/75 is diabetic)
Diet in CKD (3)
moderate protein, restrict K+, avoid high phosphate foods.
Treatment for renal osteodystrophy
Calcichew - Ca supplement
Calcium acetate - phosphate binders
Cinacalcet (calcimimetic) – reduce PTH levels
3 main ways CKD manifests and how to control them
Anaemia: Human EPO might be required
Acidosis: Consider sodium bicarbonate supplements for patients with low serum bicarbonate.
Oedema: loop diuretics, restriction of fluids
What is the most common cause of a UTI
E coli
What are the causes of a typical UTI (3)
Staphylococcus saprophyticus
Proteus mirabilis
Enterococci
Define lower and upper UTI
Lower UTI - affecting the urethra (urethritis), bladder (cystitis) or prostate
Upper UTI - affecting the renal pelvis (pyelonephritis)
Atypical causes of UTI and the population usually affected (3)
Klebsiella
Candida albicans
Pseudomonas aeruginosa
Define UTI
The presence of a pure growth of > 105 organisms per mL of fresh MSU
RF of UTI (9)
FEMALE Sexual intercourse Exposure to spermicide Pregnancy Menopause Immunosuppression Catheterisation Urinary tract obstruction Urinary tract malformation
S/s of cystitis (4)
Frequency
Urgency
Dysuria
Haematuria
S/s of prostatitis (4)
Suprapubic pain
Flu-like symptoms
Low backache
Few urinary symptoms
S/s of acute pyelonephritis (5)
High fever Rigors Vomiting Loin pain and tenderness Oliguria (if AKI)
General signs of UTI (5)
Fever Abdominal or loin tenderness Foul-smelling urine Distended bladder (occasionally) Enlarged prostate (if prostatitis)
Mx of UTI (uncomplicated, pregnant, male, pyelonephritis)
Uncomplicated: Cefalexin 500mg PO BD 3/7 OR Nitrofurantoin 50mg PO QDS 7/7
If pregnant + BF: Cefalexin; Co-amoxiclav 62
Male: 7/7 course of Cefalexin OR ciprofloxacin 500mg PO BD 14/7 (if suspicion of prostatits)
Pyelonephritis/urosepsis: Co-amoxiclav 1.2mg IV ± amikaxin (CXH/HH) or gentamicin (SMH) first 1-2/7
Define PCKD
fluid filled cysts grow on the kidney, 10% of ESRF
Method of inheritance of PCKD
Autosomal dominant inheritance, onset at 30-60 years
History of PCKD (6)
clinically silent for many years!
Acute loin pain, stone formation, abdominal discomfort
Sx of renal failure
FHx of SAH (berry aneurysms)
Examination of PCKD (5)
HTN, renal enalregment, abdominal pain ± haematuria
Ix of PCKD (5)
Haematuria, raised Hb, deranged U&E, abdominal USS, MRI angiography IF +ve 1st-degree SAH + ADPKD
Classic triad of renal cell carcinoma
haematuria, loin pain, abdominal mass.
Other presentations of renal cell carcinoma apart from the classic triad
Invasion of left renal vein compresses left testicular vein = varicocele
PUO, night sweats and rarely polycythemia
When does a renal cell carcinoma cause varicocele
Invasion of left renal vein compresses left testicular vein
Gender ratio of renal cell carcinoma
M:F = 2:1
RF of renal cell carcinoma (6)
Age; Smoking; Obesity; HTN; Dialysis (15%); certain inherited syndromes (von Hippel-Lindau, tuberous sclerosis, familial papillary renal cell carcinoma)
Which inherited syndromes cause renal cell carcinoma (3)
von Hippel-Lindau, tuberous sclerosis, familial papillary renal cell carcinoma
Ix for renal cell carcinoma (7)
Increased BP (renin), Polycythaemia or IDA (bleeding cysts), ALP (bone mets), RBCs in urine CXR - Cannon ball metastasis, filling defect ± calcification (CT/MRI intravenous urogram IVU)
Common metastases of renal cell carcinoma
Cannonball to lung
4 causes of renal artery stenosis
Atherosclerosis (80%), fibromuscular dysplasia (10%, young F)
Clues of renal artery stenosis (
↑ ↑ ↑ BP refractory to Tx (1-5% of HTN)
Worsening renal function after ACEi/ARB in bilateral RAS
Flash pulmonary oedema (sudden onset, without LV impairment on echo)
Abdominal ± carotid or femoral bruits, weak leg pulses
Ix for renal artery stenosis (3)
Ultrasound measurement of kidney size (affected size is smaller)
CT Angiogram or MR Angiography: risk of contrast nephrotoxicity
Digital Subtraction Renal Angiography = GOLD STANDARD(but invasive)
