Renal medicine Flashcards
How is an AKI measured?
Using serum creatinine
Rise of >25 micromol/L in 48 hrs
Rise of creatinine >50% in 7 days
How else can a AKI be measured?
Urine output <0.5ml/kg/hour for > 6 hours
What are some risk factors for an AKI?
CKD
Heart disease
Diabetes
Liver disease
Older age
Nephrotoxic medication e.g. NSAIDs / ACEi
Use of contrast medium e.g. during CTs
What are some causes of pre renal AKI?
- Dehydration
- Hypotension (shock)
- HF
What are some renal causes of AKI?
- Glomerulonephritis
- Interstitial nephritis
- Acute tubular necrosis
What are some post renal causes of AKI?
Kidney stones
Masses e.g. cancer in abdo
Ureter strictures
Enlarged prostate
What are results for UTI dipstick?
- Leucocytes/nitrites suggest infection
- Protein / blood suggest acute nephritis
- Glucose suggests diabetes
What can be used to look for obsruction of the urinary tract?
Ultrasound
What is the management of AKI?
Fluid rehydration with IV fluids in pre-renal
Stop nephrotoxic medications e.g. NSAIDs and ACEi
Relieve obstruction (e.g. insert catheter)
What are some complications from AKI?
Hyperkalaemia
Fluid overload
Metabolic acidosis
Uraemia leads to encephalopathy or pericarditis
What are some causes of CKD?
Diabetes
Hypertension
Age-related decline
Glomerulonephritis
Polycystic kidney disease
Medications such as NSAIDS, proton pump inhibitors and lithium
What are some risk factors for chronic kidney disease?
- Older age
- HTN
- Diabetes
- Smoking
What are some signs of chronic kidney disease (usually asymptomatic)?
- Pruritis
- Loss of appetite
- Nausea
- Vomiting
- Oedema
- Muscle cramps
- Peripheral neuropathy
- Pallor
- HTN
What are some investigations for CKD?
eGFR from U&E checked 3 months apart (to confirm diagnosis)
Proteinuria using urine albumin:creatinine ratio (> 3 is significant
Haematuria (dipstick +1 is significant) - prompt investigation for malignancy (e.g. bladder cancer)
Renal ultrasound to investigate patients with accelerated CKD, haematuria, FH of PKD
What eGFR is known as end stage renal failure?
<15 (want > 90)
What are some complications of CKD?
- Anaemia
- Renal bone disease
- CVD
- Peripheral neuropathy
- Dialysis related problems
When would referral to a specialist be considered for CKD?
eGFR < 30
ACR > 70 mg/mmol
Uncontrolled hypertensives despite 4 or more anithypertensives
Lifestyle changes to reduce risk of complications from CKD?
- Excercise
- Maintain healthy weight
- Stop smoking
- Offer atorvastatin 20mg for primary prevention of CVD
- Low phosphate, sodium and potassium diet
How to treat complications in CKD?
Oral Sodium bicarbonate to treat metabolic acidosis
Iron and erythropoietin to treat anaemia
Vitamin D to treat bone failure
Dialysis in end stage renal failure
Renal transplant
What is the medication to treat hypertension in CKD patients? What needs to be monitored?
ACE inhibitors (aim to keep BP < 140/90)
Serum potassium needs monitoring as CKD and ACEi cause hyperkalaemia
Why does anaemia of chronic disease occur in CKD?
How is it treated?
Healthy kidneys produce erythropoietin (stimulates production of RBC)
Exogenous erythropoeitin (blood transfusions should be limites as sensitise immune system “allosensitisation” so transplanted organs more likely to be rejected)
Iron deficiency should be treated before offering erythropoetin
What is:
Osteomalacia
Osteoporosis
Osteosclerosis?
Osteomalacia = softening of the bones
Osteoporosis = brittle bones
Osteosclerosis = hardening
What are the x-ray changes in renal bone disease?
Spine X-ray = sclerosis of both ends of vertebra (denser white) and osteomalacia in centre of vertebra = classically known as “rugger jersey” spine after stripes found on a rugby shirt
What electrolyte / hormonal abnormalities occur due to CKD?
High serum phosphate (low excretion)
Low active vitamin D (kidney metabolises vit D to active form, needed for calcium absorption from intestines / kidneys)
Secondary hyperparathyroidism (due to low calcium) causing increased osteoclast activity
Why does osteomalacia occur in CKD?
Increased turnover of bones without adequate calcium supply
Why does osteosclerosis occur in CKD?
Why does osteoporosis occur in CKD?
Osteoblasts increase to match osteoclasts by creating new bone but it’s not mineralised due to low calcium level
Osteoporosis = can exist alongside renal bone disease due to other risk factors e.g. age / use of steroids
What is given to patients with CKD?
Active vit D (calcitriol)
Low phosphate diet
Bisphosphonates for osteoporosis
What are 2 acute indications for dialysis?
AEIOU
Acidosis (not responding to treatment)
Electrolyte abnormalities (hyperkalaemia not responding)
Intoxication (overdose of certain meds)
Oedema (pulmonary)
Uraemia symptoms e.g. seizures
What are the 3 options for dialysis?
Continuous ambulatory peritoneal dialysis
Automated peritoneal dialysis
Haemodialysis
What is peritoneal dialysis?
Dialysis which uses the peritoneal membrane as the filtration (solution with dextrose added to peritoneal cavity - the solution is then replaced as it filters into cavity)
Continuous = dialysis solution is always in peritoneum (replaced e.g. 2L replaced 4 times a day)
Automated = overnight with a machine replaceing fluid taking 8-10 hours
Involves a Tenckhoff catheter - plastic tube inserted into peritoneal cavity allowing passing of dialysis solution
What are some complications of peritoneal dialysis?
Bacterial peritonitis (glucose makes breeding ground)
Peritoneal sclerosis (thickening ans scarring of membrane)
Weight gain due to absorption of carbs in dextrose
How is blood accessed for haemodialysis?
AV fistula or tunnelled cuffed catheter
What is a tunnelled cuffed catheter?
Tube is inserted into subclavian or jugular vein with tip sitting in SVC or right atrium (two lumens - one for blood entering / leaving)
Ring called “Dacron cuff” surrounding catheter promoting healing and adhesion of tissue to cuff making catheter more permanent
Complications = infection and blood clots
What are the two types of AV fistulas?
- Radio-cephalic
- Brachio-cephalic
- Brachio-basilic
Requires 4 week to 4 month maturation
What are some complications of an AV fistula?
- Aneurysm
- Infection
- Thrombosis
- Stenosis
- STEAL syndrome
- High output heart failure
What is STEAL syndrome in AV fistula?
Ischaemia distal to the AV fistula
What is high output heart failure?
Caused by AV fistula increasing pre-load in heart
Can blood be taken from AV fistula?
NO
What are kidney donor matches based off?
HLA types (A/B/C) on chromosome 6
In a donated kidney - is the ureter donated also?
Yes typically using hockey stick incision
What is the usual lifelong immunosuppression regime for kidney donors?
Tacrolimus
Mycophenolate
Prednisolone
(other possibles = cyclosporine, sirolimus, azathioprine)
What are some complications related to a kidney transplant?
- Rejection
- Failure
- Electrolyte imbalances
What are some complications related to the immunosuppressants used in kidney transplant?
- IHD
- T2DM (steroids)
- Infections
- Non-hodgkin lymphoma
- Skin cancers particularly squamous cell carcinoma
What is nephritis?
A general term for inflammation of the kidneys (non-specific term)
What is nephritic syndrome?
Group of symptoms (not diagnosis):
- Haematuria
- Oliguria
- Proteinuria (moderately raised, less than 3g/24 hrs)
- Fluid retention
What is nephrotic syndrome?
- Peripheral oedema
- Proteinuria >3g/24 hours
- Serum albumin less than 25g/L
- Hypercholesterolaemia
What is interstitial nephritis?
Inflammation in space between cells and tubules (interstitium)
Two types = acute interstitial nephritis and chronic tubulointerstitial nephritis
What is glomerulosclerosis?
Term to describe scarring of tissue in glomerulus (not a diagnosis)
Causes = any type of glomerulonephritis / obstructive uropathy and by specific disease e.g. FSGS
What are some types of glomerulonephritis?
Minimal change disease
Focal segmental glomerulosclerosis
Membranous glomerulonephritis
IgA nephropathy (AKA Berger’s disease)
Post streptococcal glomerulonephritis
Rapidly progressive glomerulonephritis
Goodpasture Syndrome
How are most types of glomerulonephritis treated?
Immunosuppression (e.g. steroids)
Blood pressure control by blocking RAAS (e.g. ACEi or ARBs)
What is the most common cause of nephrotic syndrome in children / adults?
Children = minimal change disease (usually idiopathic and treated with steroids)
Adults = FSGS
What is the most common cause of primary glomerulonephritis?
IgA nephropathy (peak in the 20s, histology shoes IgA deposits and glomerular mesangial proliferation)
What is the most common type of glomerulonephritis overall?
Membranous glomerulonephritis
What does membranous glomerulonephritis show on histology? When does it occur?
IgG and complement deposits on the basement membrane
Bimodal peak in 20s and 60s (majority idiopathic or can be secondary to malignancy, rheumatoid disorders and drugs e.g. NSAIDs)
How does post strep glomerulonephritis present? How does it progress?
1-3 weeks after strep infection (tonsillitis / impetigo)
Develop a nephritic syndrome
Usually full recovery
What happens in goodpastures syndrome and how does it present?
Anti GBM antibodies causing nephritic syndrome and pulmonary haemorrhage (haemoptysis)
What can cause AKI and haemoptysis?
Goodpasture syndrome (associated with anti-GBM antibodies)
Granulomatosis with polyangiitis (AKA Wegener’s granulomatosis - vasculitis associated with ANCA - also have wheeze, sinusitis and saddle-shaped nose)
When does rapidly progressive GN present?
Often secondary to goodpastures
Histology shows “cresenteric GN”
Patients are very ill but respond to treatment
What is the most common cause of glomerular pathology and what happens?
What is a key feature?
Diabetes - chronically high glucose passing through causing scarring (glomerulosclerosis)
Proteinuria
What is the treatment of choice for diabetics with poor blood pressure?
ACEi (should be started in diabetics even if BP normal)
What is interstitial nephritis?
What are the two types?
Inflammation of the space between cells and tubules
Acute interstitial nephritis and chronic tubulointerstitial nephritis
How does acute interstitial nephritis present?
What is it usually caused by?
What is the management?
Presents = AKI, hypertension (other features of hypersentitivity = rash, fever, eosinophilia)
Hypersensitivity reation to drugs (NSAIDs or abx) or an infection
Management = steroids
What is acute tubular necrosis?
Necrosis of the epithelial cells of the renal tubules
What are some causes of ATN?
- Shock
- Sepsis
- Dehydration
Which toxins can cause ATN?
Gentamicin
NSAIDs
Radiology contrast dye
What is found on urinalysis for ATN?
Muddy brown casts (pathognomonic)
What is the management for ATN?
- IV fluids
- Stop nephrotoxic medication
- Treat complications
What is renal tubular acidosis?
Metabolic acidosis due to pathology in the tubules of the kidneys (tubules responsible for balancing hydrogen and bicarbonate ions between blood and urine)
What is type 1 renal tubular acidosis?
Distal tubule is unable to excrete hydrogen ions
What are the causes of renal tubular acidosis?
- Genetic
- SLE
- Sjogren’s
- Primary biliary cirrhosis
- Hyperthyroidism
- Sickle cell anaemia
- Marfan’s syndrome
How does type 1 renal tubular acidosis present?
- Failure to thrive in children
- Hyperventilation to compensate for metabolic acidosis
- CKD
- Bone disease (osteomalacia)
What are the lab results for type 1 renal tubular acidosis?
- Hypokalaemia
- Metabolic acidosis
- High urinary pH (above 6)
What is the treament of type 1 renal tubular acidosis?
Oral bicarbonate
What is the problem in type 2 renal tubular acidosis?
What is the main cause?
What are the lab results?
What is the treatment
Proximal tubule is unable to reabsorb bicarbonate from urine into blood
Faconi’s syndrome is main cause
Results = hypokalaemia, metabolic acidosis, high urinary pH > 6
Treat with oral bicarbonate
What is type 2 renal tubular acidosis?
Combination of type 1 and type 2 (rare)
What is type 4 renal tubular acidosis?
Reduced aldosterone
What can cause type 4 renal tubular acidosis?
Adrenal insufficiency
ACEi
Spironolactone
SLE
Diabetes
HIV
What are the results in type 4 renal tubular acidosis?
Hyperkalaemia
High Chloride
Metabolic acidosis
Low urinary pH
What is the treatment for type 4 renal tubular acidosis?
Fludrocortisone
Sodium bicarbonate and treatment of the hyperkalaemia
What is haemolytic uraemic syndrome?
When there is thrombosis in small blood vessels throughout the body
What is haemolytic uraemic syndrome usually caused by?
Shiga toxin
What is the classic triad seen in haemolytic urarmic syndrome?
Haemolytic anaemia
Acute kidney injury
Thrombocytopenia (low platelets)
Where does the shiga toxin come from?
E.Coli 0157 (and shigella)
How does haemolytic uraemic syndrome present?
Initial gastroenteritis with bloody diarrhoea
then:
- Reduced urine output
- Haematuria
- Abdo pain
- Lethargy
- Confusion
- Hypertension
- Bruising
What is the treatment of haemolytic uraemic syndrome?
- Antihypertensives
- Blood transfusions
- Dialysis
In rhabdomyolysis what do the cells release?
- Myoglobin
- Potassium
- Phosphate
- Creatine Kinase
What is the most immediately dangerous breakdown product?
Potassium - arrhythmias
What is released in rhabdomyolysis which is toxic to the kidneys?
Myoglobin
What can cause rhabdomyolysis?
- Prolonged immobility
- Rigorous exercise
- Crush injury
- Seizures
What are some signs of rhabdomyolysis?
- Muscle aches and pains
- Oedema
- Fatigue
- Confusion
- Red/brown urine
What are the investigations for rhabdomyolysis?
CK blood test
Myoglobin on dipstick (myoglobinurea)
U&Es for hyperkalaemia and AKI
ECG
What is the treatment for rhabdomyolysis?
IV fluids (to encourage filtration of breakdown products)
Treat hyperkalaemia (can cause VF)
Consider IV sodium bicarbonate (makes urine more alkaline reducing toxicity of myoglobin on kidneys)
Consider IV mannitol (increases GFR to help flush breakdown products and reduces oedema)
Treat complications
What are some causes of hyperkalaemia?
AKI
CKD
Rhabdomyolysis
Adrenal insufficiency
Tumour lysis syndrome
What medications can cause hyperkalaemia?
Aldosterone antagonists
ACE inhibitors
Angiotensin II receptor blockers
NSAIDs
What are the ECG changes (required if potassium > 6) in hyperkalaemia?
- Tall T waves
- Flattened P waves
- Broad QRS complexes
What are the main treatment options for lowering potassium?
Insulin and dextrose
IV calcium gluconate stabalises the heart
What are some other options for lowering serum potassium?
Nebulised salbutamol (drives potassium into cells)
IV fluids (increases urine output thus loss from kidneys)
Oral calcium resonium draws potassium out of gut into stools (suitable for milder cases of hyperkalaemia)
Sodium bicarbonate (IV / oral) to drive potassium into cells as acidosis is corrected
Dialysis if severe / persistent case associated with renal failure
What is associated with PKD?
Hepatic cysts
Cerebral aneurysms
How is PKD diagnosed? What is the mode of inheritance?
Ultrasound / genetic testing
Dominant (more common) or recessive
What are some complications of PKD?
- Chronic loin pain
- HTN
- CVD
- Gross haematuria (cyst rupture)
- Renal stones
- End stage renal failure
When does autosomal recessive PKD present?
What does it result in?
Preganancy with oligohydraminos
Underdevelopment of lungs causing respiratory failure
Causes end stage renal failure before reaching adulthood
What is the main treatment for PKD?
Tolvaptan (vasopressin receptor antagonist) slows development of cysts and progression of renal failure
How are the complications of PKD managed?
- Antihypertensives for HTN
- Analgesia for renal colic
- Abx for infection
- Dialysis for end stage renal failure
- Renal transplant
What are some other management steps for PKD?
Genetic counselling
Avoid contact sports due to the risk of cyst rupture
Avoid anti-inflammatory medications and anticoagulants
Regular ultrasound to monitor
Regular bloods to monitor function
Regular blood pressure to monitor for hypertension
MR angiogram can be used to diagnose intracranial aneurysms in symptomatic patients or those with a family history
