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Conversion of sorbitol to mannitol when used parenterally
Summary
Unexpectedly, mannitol was found in urine samples from patients receiving total parenteral nutrition. This suggests sorbitol can convert to mannitol through a secondary metabolic pathway, impacting patient monitoring.
Area of Science:
- Biochemistry
- Clinical Nutrition
- Metabolism
Background:
- Total parenteral nutrition (TPN) is crucial for patients unable to consume food orally.
- Monitoring patient metabolism is essential for effective TPN management.
- Sorbitol is sometimes used in TPN formulations.
Purpose of the Study:
- To investigate the unexpected observation of mannitol excretion in patients receiving TPN.
- To elucidate the metabolic pathway responsible for mannitol formation from sorbitol.
Main Methods:
- Urinary levels were measured in patients receiving TPN, including glucose, sorbitol, amino acids, and soya oil.
- Analysis focused on identifying unexpected metabolites.
- Physiological pathways of sorbitol metabolism were examined.
Main Results:
- Mannitol was unexpectedly detected in the urine of patients undergoing TPN.
- This excretion is hypothesized to result from the conversion of sorbitol.
- A secondary catabolic pathway, distinct from glycolysis, appears to be involved.
Conclusions:
- Sorbitol can be converted to mannitol in vivo.
- This conversion occurs via a physiological pathway involving fructose, a sorbitol metabolite.
- The findings have implications for monitoring patients receiving sorbitol-containing TPN.