Clinical Assessment of Function and GFR

Question 1

Characteristics of the ideal marker to measure GFR

Answer 1

Constant production
Freely filtered by the glomerulus
No tubular reabsorption or secretion
No extrarenal elimination/degradation
Does not influence GFR
Cheap, convenient, safe, easily assayed

Question 2

Creatinine

Answer 2

Endogenously produces metabolic product of creatine and phosphocreatine, both found primarily in skeletal muscle
Production is proportional to muscle mass
Generally constant production
Freely filtered at glomerulus
Convenient and cheap to measure
There is some tubular secretion though so it overestimates the true GFR

Question 3

Certain populations where estimating equations are less accurate

Answer 3

Extremes of age and body size
Severe malnutrition or obesity
Diseases of skeletal muscle
Paraplegia, quadriplegia
Pregnancy

Question 4

Can you use GFR estimating equations in AKI?

Answer 4

NO

Individual is not in a steady state

Question 5

CKD definition

Answer 5

Presence of kidney damage or decreased kidney function for at least 3 months
Kidney damage = albuminuria, urine sediment abnormalities, imaging abnormalities, pathologic abnormalities, kidney transplant

Question 6

Albuminuria

Answer 6

Normally only a small amount of albumin in the urine
With kidney damage the permeability increases and albumin increases in the urine
One of the most frequently assessed markers of kidney damage
More albumin = high risk of progression to end stage renal disease

Question 7

CKD associated complications

Answer 7

Anemia
Bone disease, abnormal Ca and PO4 metabolism
Acidosis
HTN and CV disease
Malnutrition
Symptoms: abnormal taste, loss of appetite, pruritis
Increased risk of AKI

Question 8

Range of urine concentration

Answer 8

50-1200 mosm/kg