## Calculation of reabsorption and secretion rates

- The reabsorption or secretion rate is the difference between the amount filtered across the glomerular capillaries and the amount excreted in urine. It is calculated with the following equations:

Filtered load = GFR x [plasma] Excretion rate = V x [urine] Reabsorption rate = Filtered load - Excretion rate Secretion rate = Excretion rate - Filtered load

- If the filtered load is greater than the excretion rate, then net reabsorption of the substance has occurred. If the filtered load is less than the excretion rate, then net secretion of the substance has occurred.

 Effect on GFR Effect on RPF Effect on Filtration Fraction Constriction of afferent arteriole (caused by I PGC) i No change Constriction of efferent arteriole (caused by T PGC) I (T GFRAl RPF) Increased plasma [protein] (caused by T tt-qc) No change (4- GFR/unchanged RPF) Ureteral stone (caused by T PBS) No change (1 GFR/unchanged RPF)

GFR = glomerular filtration rate; RPF = renal plasma flow.

GFR = glomerular filtration rate; RPF = renal plasma flow.

Glomerular

Glomerular Figure 5-4. Processes of filtration, reabsorption, and secretion. The sum of the three processes is excretion.

- Example: A woman with untreated diabetes mellitus has a GFR of 120 ml/min, a plasma glucose concentration of 400 mg/dl, a urine glucose concentration of 2500 mg/dl, and a urine flow rate of 4 ml/min. What is the reabsorption rate of glucose?

Filtered load = GFR x Plasma [glucose] = 120 ml/min x 400 mg/dl = 480 mg/min Excretion = V x Urine [glucose]

= 4 ml/min x 2500 mg/dl = 100 mg/min Reabsorption = 480 mg/min - 100 mg/min = 380 mg/min

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### Responses

• Emilia
What is renal reabsorption rate?
3 years ago
• Michelina
How to calculate secretion rate of a drug?
3 years ago
• andreas
How to calculate glucose reabsorption?
3 years ago
• YVONNE SCHMIDT
How to calculate reabsorbed substance?
3 years ago
• Wolfgang Osterhagen
How to calculate glucose excretion?
2 years ago
• MORGAN
How to calculate glucose filtration per minute?
1 year ago
• charles
How do you calculate glucose reabsorbed?
1 year ago
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How to calculate reabsorption rate of urea?
1 year ago
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How to calculate reabsorption given clearance and excretion rate?
1 year ago
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How to calculate reabsorption of solute x in renal?
1 year ago
• kiros
1 year ago
• marco
What to do for smooth excretion?
1 year ago
How to find excretion rates?
12 months ago
• Jonas Eichmann
What are the equations for clearance, excretion and filtrate load?
11 months ago
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How to calculate rate of excresion?
11 months ago
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How to calculate rate of water reabsorption by tubule?
11 months ago
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How to calculate rate of urination?
10 months ago
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How to calculate the rate of urine excreted?
8 months ago
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How to do renal calculation of excretion vs absorbed?
7 months ago
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How to calculate the percentage of filtrate reabsorbed by the kidney tubules?
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How to calculate urinary excretion?
6 months ago
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How to calculate renal absorption rate?
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How to calculate glucose reabsorption rate?
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How to do solve reabsorption and secretion rate?
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How to find the percentage of filtrate reabsorbed by the kidney tubules examples?
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