GFR
T/F: The GFR can tell us the cause of kidney damage/disease.
False! A reduced GFR can indicate the progression of an underlying disease, but it can’t tell us the cause of kidney disease
What are the two most common causes of etiologies/causes of progressive renal failure?
-hypertension
-DM (diabetic nephropathy)
T/F: Serum creatine levels can vary because of muscle mass and diet, so they are not recommended as an evaluation of renal function.
True!
T/F: If a patient loses one-half of their total kidney mass and nephrons, you can expect them to have half of the normal GFR.
False! Because of hyperfiltration, there is not an exact correlation between loss of nephrons and the loss of GFR (the kidneys are pretty good at compensating for the lost nephrons)
T/F: Once half of the total nephrons have lost function, CKD progresses similarly regardless of the etiology/cause.
True!
T/F: A blood urea nitrogen (BUN) test is the most accurate marker of renal function.
False!
T/F: A patient who has recently recovered from a serious nephritis infection will automatically be listed as having stage 1 kidney disease?
True! Stage 1 describes any potential kidney damage. Anyone who has a serious kidney infection (such as nephritis) will be listed as having stage 1 kidney disease so it’s on the radar for their future health care team.
What is hyperfiltration?
The kidneys compensate for nephron loss through hyperfiltration of the remaining nephrons. This is how a patient can have a normal GFR even though they have kidney damage.
How does renal failure affect RBC levels?
The kidneys produce erythropoietin. Without this, RBC production in the bone marrow will drop significantly.
How many months of albuminuria indicates chronic kidney disease?
3 or more months of albumin in the urine.
What is creatinine clearance?
It’s the amount of excreted creatinine is measured and compared with the amount of circulating serum creatinine. It is a more precise way to estimate GFR.
The GFR can be as low as __% before signs of renal dysfunction start to appear (rise in serum creatinine and BUN).
50%
Bonus Q: what is the average GFR rate for males and females?
What are at least two potential causes of increased proteinuria?
-Defects in the glomerular filtration barrier to plasma proteins
-Incomplete tubular reabsorption of proteins
-Overflow proteinuria from increased serum levels of protein (more commonly due to neoplasm than to dietary intake)
-Urinary tract infection
Why is measuring creatinine clearance even more important in older adults?
As you lose lean muscle, your Cr levels decrease. Meaning that older adults might appear to have ‘normal’ serum creatinine levels even though their renal function is impaired. A creatinine clearance will be able to show a discrepancy between their serum and excreted Cr levels.
Diagnosis of CKD requires:
-Decline of kidney function for 3 months or more
AND
-Evidence of kidney damage (e.g. albuminuria or abnormal biopsy)
OR
-GFR <60 mL/min/1.73 m2
What is the average GFR in males and females?
Average GFR in males = 125 mL/minute
Average GFR in females = 115 mL/min
Diabetic nephropathy is characterized by: (list at least 1, there are 3 in total)
-Persistent albuminuria confirmed on at least 2 occasions 3-6 months apart
-Progressive decline in glomerular filtration rate
-Elevated arterial blood pressure
What is cystatin C?
A protein that should be completely filtered at the glomerulus (none reabsorbed). It is not affected by age, muscle, or diet, unlike creatinine. It is broken down in the tubules, so it shouldn’t appear in the urine.
What are at least 3 potential complications caused by renal failure?
-Generalized edema
-Pulmonary crackles
-Anemia
-Hypertension
-Hyperkalemia
-Hyperphosphatemia
-Hypocalcemia
-Hyperparathyroidism