PHS 303 Renal Clearance Flashcards
What is renal clearance
Volume of plasma completely cleared of a particular substance by kidneys per minute not the amount of the (substance removed)
Varies for different substances depending on how the kidneys handle each substance
Unit ml/min
If a substance is filtered only and not reabsorption or secreted what is the plasma clearance?
PC = GFR
If a substance is filtered and partially reabsorbed plasma clearance?
PC < GFR
If a substance is filtered and completely what is the plasma clearance?
PC = 0
If a substance is filtered and secreted what is the plasma clearance?
PC > GFR
Criteria of a substance use for GFR
Freely filtered
not secreted by the tubular cells
not reabsorbed by the tubular cells should not be toxic
should not be metabolized
easily measurable
Examples of GFR Markers
Creatinine
Inulin 
What’s the Clearance ratio
Clearance of any substance X compared with the clearance of insulin
The clearance of a particular substance (Cx) divided by GFR
Importance of renal clearance
To quantify several aspects of renal functions:
Rate of glomerular filtration
rate of blood flow
Assess severity of renal damage
tubular reabsorption
tubular secretion of different substances
Function of renal clearance
Clearance can also give an indication of the function of the kidneys
it can be used to determine renal handling of a substance
clearance values can also be used to determine how the nephron handles a substance filtered into it and this method the clearance for inulin a creatinine is calculated and then compared with the clearance of the substance being investigated
Factors Affecting Renal Clearance
• Physicochemical properties of a substance
• Plasma conc. of a substance
• Distribution and handling characteristics of a
substance
• Urine pH
• Renal blood flow
• Biological factors
• Disease conditions
How much urine do we produce per day
Volume : 1,000 to 1,500 mL/day
pH of urine
Reaction : Slightly acidic with pH of 4.5 to 6
