Chemical Pathology: Renal Failure Flashcards
What is the 2 endocrine functions of the kidney
EPO
Vitamin D activation
What is GFR used for
Measurement of renal functional capacity & reflects the amount of functional nephrons
Highly specific & sensitive for change in renal function
What is the GFR definition
Volume of plasma that can be cleared of an ideal substance per unit of time corrected to body surface area
What is the definition for renal clearance
Rate at which kidneys clear blood plasma of substances
What is 3 criteria’s for an ideal substance
- Stable plasma concentration& only in ECF
- Freely filterable through glomerulus
- Not reabsorbed or excreted by tubule
What is the clearance ratio & meaning
=1 freely filtered & not secreted
<1 not freely filtered & or reabsorbed
>1 freely filtered & secreted
What is creatinine
Cyclic anhydride of phospho-creatine
Where is creatinine found & function thereof
Intra-cellular component of skeletal muscle
Storage & transfer of phosphate for muscle contraction
3 places where creatinine is synthesized
Liver, kidney & pancreas
What provides the stable production rate of creatinine
Spontaneous conversions of muscle
Why is creatinine not an ideal substance to measure for renal function
High concentration secreted fat renal tubules & GIT
What is 3 ways in which GFR can be measured
- Creatinine
- S-cystatin C
- Exogenous tracers
What is the tools used to measure creatinine in adults & children
Adults KDIGO
Child IDMS traceable Schwartz
What is the 3 limitations of creatinine measurement
- People w/ extreme muscle mass
- People w/ extreme creatinine intake
- Unstable renal function (hospitalized)
What is cystatin C
Non glycosylated low molecular weight protein in all cells
What is the benefit of using cystatin C instead of creatinine for renal function measurement
Plasma concentration is less influenced by age, gender & muscle mass
Renal corpuscle filtration w/ near total reabsorption & catabolism w/ little to no excretion
When is exogenous tracers used testing for renal function
Pre & post transplant as it is more accurate
What 2 tracers are used exogenous tracers in kidney function testing
Cr51 EDTA (radioactive)
Lohexol (more expensive)
How does exogenous tracers work
Tracers injected w/ multiple blood samples to measure concentration of tracers cleared by glomerulus
What is acute renal failure
Renal pathology involving all nephrons with loss of function in glomerular & tubular
What is the 2 phases of acute renal failure
- Oliguria
- Polyuria
What is the relationship between creatinine/urea & acute renal failure
Urine excretion of urea & creatinine is less than produced & serum levels increase
What is the pathophysiology of acute renal failure
- Vasoconstriction & desquamation of tubular cells or death
- Slough off of viable or dead cells that can cause an obstruction
- There can either be proliferation & differentiation into normal tissue or inhibition of repair & progression leading to chronic renal disease
What is the 3 classifications of renal failure
- Pre renal failure
- Intrinsic renal failure
- Post renal failure
What does pre renal failure result in
Leading to hypoperfusion of the kidney & increased serum BUN & creatinine
Decrease blood pressure & decrease GFR causing accumulation of waste products in blood
The decrease in GFR leads to activation of RAAS leading to Na & water retention & urea follows Na retention