How can we model the water transport through the kidney?

A problem presented at the UK MMSG Oxford 2005.

Presented by:
Dr Susan Franks (Computational Toxicology, Health and Safety Laboratory)
S Franks, J King, H Mason, JB van den Berg

Problem Description

Biological monitoring is often employed in assessing occupational exposure to chemicals and generally relies on the analysis of substances in an end of work-shift urine sample. The process of urine production has a significant impact on the concentration of chemical measured in these samples and typically, these results are normalised against creatinine production (as a measure of glomerular filtration) to overcome the dilution effects caused by urine production. However, as net renal excretion is a combination of glomerular filtration, tubular secretion and tubular reabsorption, the correlation between creatinine and renal chemical clearance is often inadequate. The interpretation of these samples would therefore be greatly improved by a mathematical model for creatinine excretion and water transport through the kidney.

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Study Group Report

In occupational medicine, measurements of levels within the urine of toxic chemicals, or their metabolites, are used to indicate the level of exposure of workers to chemicals. In a worker's body the kidney is the main organ taking care of the excretion of unwanted/toxic chemicals and the recovery of useful ones, via three mechanisms: filtration, reabsorption and secretion. We model these processes, taking the fairly complicated geometry of the kidney into account, and study how the flow rate of urine influences the concentration of certain drugs/toxins in a urine sample.

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