Renal Failure Flashcards
Oliguria
Urine output?
Urine volume less than 400-500 mL/day
Associated with more severe forms of AKI
Definition of Acute Kidney Injury (AKI)
Loss of renal function over hours to weeks.
Prerenal azotemia?
Acute decrease in glomerular filtration rate due to renal hypoperfusion in the absence of cellular damage.
Acute Tubular Necrosis
Acute decrease in renal function due to ischemic or toxic damage.
One of the most common mechanisms of AKI seen in clinical setting.
Postrenal failure
Decrease in renal function due to an obstructive process involving the tubules, ureters or bladder.
What is the leading cause of CKD (Chronic Kidney Disease) and end-stage renal disease in the world?
Diabetic Nephropathy
Uremia?
Multi-organ symptom complex resulting from biochemical abnormalities of renal failure.
Due to combination of nitrogenous organic wastes.
Why is GFR not routinely measured?
It requires administration of an exogenous substance (inulin or iothalamate) which is freely filtered and neither secreted nor reabsorbed in the tubules.
What do we use clinically to approximate GFR?
serum creatinine clearance (CrCl).
Creatinine is produced at a relatively constant rate in muscles, which is reflected by a stable plasma concentration and urinary excretion.
Equation for approximating GFR
GFR ~ CrCl = (U_creatinine X Vurine)/S_creatinine
Urine creatinine clearance usually collected over 8-24 hr period.
Normal values for CrCl in women? Men?
95+- 20 mL/min/1.73 m^2 in women
120+-25 mL/min/1.73 m^2 in men
Cockroft and Gault formula? What is it calculating?
Males: CrCl (mL/min) = (140-age) X weight / (S_creatinine X 72)
Females: value for males X 0.85
age in years, S_cr in mg/dL, weight = lean body weight in kg
equation NOT normalized for BSA!
It is the most widely used estimate for CrCl from steady state serum creatinine levels!
What is the Modification of Diet in Renal Disease (MDRD) Study Equation?
Equation used to more accurately calculate GFR
What three factors determine GFR? (simplification)
Ultrafiltration coefficient (K_f): permeability of the glomerular capillary wall.
Glomerular Hydraulic Pressure (P_GC):
Hydraulic Pressure in Bowman’s Space (P_BS)
What can decreases in GFR be attributed to?
Decrease in perfusion pressure (prerenal failure)
Increase in tubular backpressure (postrenal failure)
Loss in intrinsic filtration area or permeability of capillary wall (intrinsic failure)
