Renal Flashcards
What is AKI?
An acute drop in kidney function
How do you diagnose AKI?
AKI is diagnosed by measuring the serum creatinine
Criteria for diagnosing AKI…
Rise in serum creatinine 26µmol/L or more in 48 hours or > or equal to 50% rise in creatinine over 7 days or fall in urine output to less than 0.5ml/kg/hour for more than 6 hours in adults (8 hours in children) or more than or equal to 25% fall in eGFR in children/young adults in 7 days
What are the stages of AKI?
Stage 1= increase in creatinine to 1.5-1.9x baseline or increase in creatinine by > or equal to 26.5
Or reduction in urine output to <0?5ml/kg/hour for more than or equal to 6 hours
Stage 2= Increase in creatinine to 2.0 to 2.9 times baseline, or
Reduction in urine output to <0.5 mL/kg/hour for ≥12 hours
Stage 3= Increase in creatinine to ≥ 3.0 times baseline, or
Increase in creatinine to ≥353.6 µmol/L or
Reduction in urine output to <0.3 mL/kg/hour for ≥24 hours, or
The initiation of kidney replacement therapy, or,
In patients <18 years, decrease in eGFR to <35 mL/min/1.73 m2
When would you refer to a nephrologist in terms of AKI?
Renal tranplant ITU patient with unknown cause of AKI Vasculitis/ glomerulonephritis/ tubulointerstitial nephritis/ myeloma AKI with no known cause Inadequate response to treatment Complications of AKI Stage 3 AKI (see guideline for details) CKD stage 4 or 5 Qualify for renal replacement hyperkalaemia / metabolic acidosis/ complications of uraemia/ fluid overload (pulmonary oedema)
What are the risk factors for AKI?
Chronic kidney disease Heart failure Diabetes Liver disease Older age (>65) Cognitive impairement NSAIDS/ACE-I Use of contrast medium
What are the causes of AKI?
They can be split into pre renal, renal and post renal
Pre renal= inadequate blood supply ie: dehydration, hypotension and heart failure
Renal= intrinsic disease in the kidney, leading to a reduced filtraton of blood, may be due to…
- glomerulonephritis
- interstitial nephritis
- acute tubular necrosis
Post renal….
- obstruction to the outflow
- kidney stones
- cancer in abdo or pelvis
- ureter or uretral strictures
- enlarged prostate/prostate cancer
What are the investigations for AKI?
Urinalysis for protein, blood, leucocytes, nitrites and glucose.
Leucocytes and nitrites suggest infection
Protein and blood suggest acute nephritis (but can be positive in infection)
Glucose suggests diabetes
Ultrasound of the urinary tract is used to look for obstruction. It is not necessary if an alternative cause is found for the AKI.
What is the management of AKI?
Prevention of acute kidney injury is important. This is achieved by avoiding nephrotoxic medications where possible and ensuring adequate fluid input in unwell patients, including IV fluids if they are not taking enough orally.
The first step to treating an acute kidney injury is to correct the underlying cause:
Fluid rehydration with IV fluids in pre-renal AKI
Stop nephrotoxic medications such as NSAIDS and antihypertensives that reduce the filtration pressure (i.e. ACE inhibitors)
Relieve obstruction in a post-renal AKI, for example insert a catheter for a patient in retention from an enlarged prostate
What are the complications of AKI?
Hyperkalaemia
Fluid overload, heart failure and pulmonary oedema
Metabolic acidosis
Uraemia (high urea) can lead to encephalopathy or pericarditis
What pain relief do you use for renal colic?
IM diclofenac 75mg
What is anaemia in CKD caused by?
What is the management of anaemia in CKD?
A variety of factors
the main one is reduced erythropoietin levels
Usually a normochromic normocytic anaemia
Becomes apparent when the eGFR <35ml/min
Causes of anaemia in renal failure;
- Reduced EPO
- Reduced erythropoeisis due to toxic effects of uraemia on bone marrow
- Reduced absorption of iron
- Anorexia/Nausea due to uraemia
- Reduced red cell survival (Especially in haemodialysis)
- Blood loss due to capillary fragility and poor platelet function
- Stress ulceration leading to chronic blood loss
Need to check iron levels before giving erythropoiesis stimulating agents, may require ferrous sulphate or IV iron if on haemodialysis before giving ESA
What is hyperkalaemia classified as?
Mild: 5.5-5.9
Moderate: 6-6.4
Severe: >6.5
What are the features of hyperkalaemia on ECG?
Peaked or tall tented T waves
Loss of P waves
Broad QRS
Sinusoidal wave patterns
How do you treat hyperkalaemia?
STABILISATION OF THE CARDIAC MEMBRANES (DOES NOT ACTUALLY DECREASE SERUM K+ LEVELS)= IV CALCIUM GLUCONATE
short term shift in K+ from ECF to ICF- combined insulin/ dextrose infusion, nebulised salbutamol
Removal of K+ from the body- Calcium resonium (Orally or enema), this actually removes K+ from the body
Loop diuretics
Dialysis
How can you differentiate between Acute tubular necrosis and acute interstitial nephritis?
Acute interstitial nephritis is an inflammatory process so there would be white cells in the urine, whereas acute tubular necrosis is not inflammatory so has no cellular compartment
How do you work out alcohol units?
ml x %
What are the causes for normal anion gap metabolic acidosis?
ABCD
A- addisons
B- bicarbonate loss
C- Chloride
D- drugs
What type of alkalosis is seen in vomiting?
Hypochloraemic, hypokalaemic metabolic alkalosis
What is the mainstay of treatment rhabdomyolysis?
Rapid IV fluid rehydration
What are the features of rhabdomyolysis?
AKI with disproportionally raised creatinine elevated CK Myoglobinuria Hypocalcaemia Elevated phosphate Hyperkalaemia Metabolic acidosis
Seizure/collapse/ectasy/crush injury/statins
What is the anticoagulation of choice in AKI/CKD?
warfarin
What are the causes of CKD?
Diabetes Hypertension Age related decline Glomerulonephritis Polycystic kidney disease NSAIDS, PPIs, lithium
What are the risk factors for CKD?
Older age Hypertension Diabetes Smoking NSAIDS PPIS lithium
What are the features of CKD?
Usually CKD is asymptomatic and diagnosed on routine testing, a number of signs and symptoms might suggest CKD…
Pruritus (itching) Loss of appetite Nausea Oedema Muscle cramps Peripheral neuropathy PallorHypertension
Whatbinvestigations do you do for CKD?
Estimated eGFR can be checked using a U and E blood test
Two eGFR tests 3 months apart can confirm the diagnosis of CKD
Proteinuria can be checked using a urine albumin: creatinine ratio
A result of > or equal to 3mg/mmol is significant
Haematuria can be checked using a urine dipstick
Renal ultrasound can be used to investigate patients with accelerated CKD, haematuria, FHx of PCKD or evidence of obstruction
What is needed for a diagnosis of CKD?
EGFR of <60 or proteinuria
What are the complications of CKD?
Anaemia Renal bone disease CVD Peripheral neuropathy Dialysis related problems
How do you treat the complications of CKD?
Iron supplements for the anaemia
Vit D for renal bone disease
Dialysis in end stage renal failure
Oral sodium bicarbonate to treat metabolic acidosis
How do you treat hypertension due to CKD?
ACE-I
Offered to all pts with;
Diabetes plus ACR >3mg/mmol
Hypertension plus ACR >30mg/mmol
All patients with ACR >70mg/mmol
Serum potassium also needs to be monitored as both CKD and ACE- I both cause hyperkalaemia
What are the features of renal bone disease?
Osteomalacia (softening of bones)
Osteoporosis (brittle bones)
Osteosclerosis (hardening of bones)
What is the pathophysiology behind renal bone disease?
High serum phosphate occurs due to reduced phosphate excretion
Low active vit D because the kidney is essential in metabolising vit D to its active form
Active vit D is essential in calcium absorption from the intestine and kidneys, vit D also regulates bone turnober
Secondary hyperparathyroidism occurs because the parathyroid glands react to low serum calcium and high serum phosphate by excreting more parathyroid hormone, this leads to an increased osteoclast activity
Osteoclast activity leads to absorption of calcium from bone.
What is the management of bone disease caused by CKD?
Active forms of vitamin D (alfacalcidol and calcitriol)
Low phosphate diet
Bisphosphonates can be used to treat osteoporosis
What are the indications for Acute dialysis?
AEIOU
A= acidosis
E= electrolyte abnormalities
I= intoxication
O= oedema (severe and unresponsive pulmonary oedema)
U= uraemia symptoms- seizures or reduced consciousness
