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.

Table 5-3. Effect of Changes in Starling Forces on GFR, RPF, and Filtration Fraction

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
  • Gloria Li Fonti
    How to calculate reabsorption rate of urea?
    1 year ago
  • anni
    How to calculate reabsorption given clearance and excretion rate?
    1 year ago
  • Faramond
    How to calculate reabsorption of solute x in renal?
    1 year ago
  • kiros
    How to calculate excreted load?
    1 year ago
  • marco
    What to do for smooth excretion?
    1 year ago
  • gorbadoc
    How to find excretion rates?
    12 months ago
  • Jonas Eichmann
    What are the equations for clearance, excretion and filtrate load?
    11 months ago
  • fre-qalsi
    How to calculate rate of excresion?
    11 months ago
  • primrose
    How to calculate rate of water reabsorption by tubule?
    11 months ago
  • Rosarmosario
    How to calculate rate of urination?
    10 months ago
  • semere abrha
    How to calculate the rate of urine excreted?
    8 months ago
  • olli
    How to do renal calculation of excretion vs absorbed?
    7 months ago
  • stephan
    How to calculate the percentage of filtrate reabsorbed by the kidney tubules?
    7 months ago
  • miikka
    How to calculate urinary excretion?
    6 months ago
  • filippa
    How to calculate renal absorption rate?
    5 months ago
  • asmait medhane
    How to figure inulin clearance for urinary excretion rate of 31.9 mg/min?
    5 months ago
  • heike
    How to calculate glucose reabsorption rate?
    3 months ago
  • marcel
    How to do solve reabsorption and secretion rate?
    3 months ago
  • Amethyst Lothran
    How to calculate what percent is reabsorbed filtered load?
    1 month ago
  • abdullah
    What percentage of water filtered at the gloumer is excreted?
    30 days ago
  • isla
    How to calculate salicylate excretion equation?
    25 days ago
  • OSKAR
    How to measure excretion rate?
    20 days ago
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    How do you calculate percentage of urea that is reabsorbed?
    12 days ago
  • Curtis Kendall
    How to calculate rates of renal excretion of salicylate in moles excreted.h1?
    9 days ago
  • pansy
    How to find the percentage of filtrate reabsorbed by the kidney tubules examples?
    9 days ago
  • sanelma
    How to find filtered load?
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