GFR & Proteinuria Labs - Cohen Flashcards
What are symptoms of kidney failure? What causes them?
Frequency or Nocturia- large urine output
Edema- protein loss
Foamy Urine- protein loss
Uremia- waste product retention
What are the formulas for filtration and excretion?
What is the formula for calculating GFR based off of this?
Q_filt= GFR * [serum] Q_excr= UFR * [urine]
GFR= (UFR*[urine]) / [serum]
What is used to measure the GFR? Why?
Creatine; it assumed to be neither excreted or resorbed
Another option is inulin, but that is not produced endogenously.
What is the normal range for serum creatinine?
- 9-1.3 mg/dL for men
- 8-1.0 mg/dL for women
- 5-1.0 mg/dL for kids
These are all HIGHLY variable.
What are the stages of kidney failure?
Stage I- 100-90 ml/min Stage II- 89-60 ml/min Stage III- 59-30 ml/min Stage IV- 29-15 ml/min Stage V- less than 15 ml/min
What three factors can affect serum creatinine calculations?
Age (older people produce less creatinine)
Gender (females produce less creatinine)
Race (blacks produce more creatinine)
What is the Cockcroft-Gault equation?
Creatinine_Cl=(140-age)weight/ (72serum_creatinine)
this is multiplied by 0.85 in women
What are some limitations with calculating creatinine clearance?
Depending on the formula used, there can be a lot of variability.
Is not useful for acute kidney injury
How is proteinuria measured? What is the accuracy?
Collected urine has a dipstick, which changes color according to protein content.
very accurate
How can urine be collected for proteinuria testing?
24 hour collection
spot collection (less accurate)
How is proteinuria quantified?
Semi-quantitatively
1,2,3,4+
Do healthy people have protein in their urine?
Yes, tubular proteins
What is micro-albuminuria?
A moderate increase in albumin in the urine
30-300 mg albumin in 24 hours
20-200 ug albumin per minute
Histologically, what can be seen in diabetic nephropathy?
Thickening of the basement membrane
