Urology E83 Flashcards
Definition of Acute Renal Failure
Defined as a rapid and reversible decline in GFR that can occur in either pre-existing normal renal function (classic ARF) or with pre-existing renal disease (acute on chronic renal failure).
Marked by rise in serum creatinine or by azotemia (rise in blood urea nitrogen concentration)
What is the RIFLE criteria?
Acronym that defines the 3 grades of increasing severity of ARF [risk, injury and failure] and 2 outcomes [loss and end stage kidney disease]. It looks at creatinine and urine output.
Etiology of AKI
- Prerenal 40-70% cases: normal pressure in glomeruli is 90mm/hg when systolic falls below 70, blood flow and filtration rate also falls and urine volume decreases. Occurs in blood loss, severe burns, cardiac failure. Dehydration
- Intrinsic (or direct renal parenchymal damage 10-50%: structural injury in the kidney caused by hypotensive shock, septicaemia, bilateral pyelonephritis
- Postrenal (10% of case): Mechanical obstruction of the urinary collecting system including the renal pelvis, ureters, bladder or urethral resulting in obstructive uropathy or post renal AKI. Caused by obstruction by stones or fibrosis(Ormond’s disease) , malignancies
Clinical Feature of AKI:
3phases
1. Oliguria: daily <300ml, dark urine with specific gravity of 1.010
2. Diuresis: large amounts of dilute urine passed
3. Recovery: damanaged renal cortex recovers unless irreversible damage
Other sx: swelling in legs, lethargy, confusion, nausea, weakness, irregular HR
Dx of AKI:
Kidney function: increased BUN and creatinine, CBC, blood Na and K high
Urinalysis: proteinuria, haematuria
US: exaluating existing renal disease and obstruction
Renal biopsy: identify intrarenal cause of AKI
Normal GFR: 100-130m/min for M and 90-120 for F
AKI is dx based on result of serum creatinine and urine volume tests if one or more is present:
- SCr increase by 0.3mg/dL or more within 48hrs
- SCr increase of at least 150% withing 7day period
- Urine volume less than 0.5ml/kg/h over 6hr period
Tx of AKI
Maintain volume of homeostasis and correction of biochemical abnormalities are primary goals
Correction of fluid overload with furosemide
Severe acidosis with alkali administration
Dietary changes: restrict salt and fluid is crucial in oliguric renal failure.
AVOID nephrotoxic medications ACE inhibitors, ARBs, NSAIDs
ESWL bread up stones in postrenal ARF
Chronic Renal failure def
CRF or chronic kidney disease CKD is progressive loss of kidney function over a period of months or years ude to renal injury or decreased GFR. eGFR is less than 60ml/min/1.73m^2 for at least 3 months
What is the KDIGO CKD classification?
Recommends details about the cause of CKD and classifies into 6 categories based off GFR. Also 3 levels of albuminuria (A1, A2, A3)
G1: GFR 90ml/min/1.73m2 or above
G2: GFR 60-89ml/min/1.73m2
G3a: GFR 45-59ml/min/1.73m2
G3b: 30-44ml/min/1.73m2
G4: 15-29ml/min/1.73m2
G5: GFR <15ml/min/1.73m2 or treatment by dialysis
Causes of CKD
DM2 30-50% DM 1 3.9%
Hypertension (second most common)
Primary glomerulonephritis
Chronic tubulointerstitial nephritis
Renal cystic disease
Obstructive nephropathy
Sx of CKD
Uraemia -> leads to neuropathy, cardiomyopathy. Calcium bone disease
Nausea vomiting
Fatigue and weakness
Changes in urination
Muscle twitches and cramps
Peripheral and pulmonary edema
Dx of CKD
Infusion pyelography
Retrograde pyelography
Blood,, urine tests and kidney biopsy to check for: increased BUN and creatinine, hyperkalaemia, decreased GFR hypocalcaemia, hyperphosphatemia, increased cholesterol and triglycerides
US CT MRI
Tx for CKD
No cure only symptomatic control and reduce complications
Dietary changes, low protein sodium, low salt diet and diuretic to reduce swelling
High BP meds: ACE inhibitors or ARBs to lower pressure and preserve kidney function
Medications to lower cholesterols- statins
Medications to protect bones: calcium vit D supplements
At stage 5 CKD kidney replacement is usually required in the form of dialysis or kidney transplant
What is dialysis?
Dialysis- artificially removes waste products and extra fluid from the blood.
o In hemodialysis, a machine filters waste and excess fluids from the blood.
o In peritoneal dialysis, a thin tube (catheter) inserted into the abdomen fills the abdominal cavity with a dialysis solution that absorbs waste and excess fluids. After a period of time, the dialysis solution drains from the body, carrying the waste with it.
What is kidney transplant?
The kidney is implanted in right iliac fossa extraperitoneally. Renal vein is anastomosed to common iliac vein end to side and renal artery is anastomosed to internal iliac artery end to end. Ureter is implanted in the bladder directly in majority of cases.
Old kidneys are kept in. Bilateral nephrectomies are done in: infected kidneys, large polycystic kidneys or uncontrollable hypertension
What can prevent a pt from being eligible for kidney transplant?
Advanced age
Severe heart disease
Active or recent cancer treatment
Dementia or poorly controlled mental illness
Alcohol or drug abuse
