Creatinine as a normalization factor to estimate the representativeness of urine sample - Intra-subject and...

Area of Science:

• Radiological protection
• Biomedical analysis
• Occupational health

Background:

• In-vitro bioassay for radiation workers typically uses overnight urine samples (~12h) to assess radionuclide excretion.
• Uncertainty in internal dose calculation arises from unknown urine collection durations (10-16h).
• The International Atomic Energy Agency (IAEA) suggests using specific gravity or creatinine excretion for normalization to minimize uncertainty.

Purpose of the Study:

• To standardize a chemical procedure for creatinine estimation in urine.
• To evaluate the utility of creatinine as a normalization factor for urine sample analysis in radiation dose assessment.
• To assess creatinine excretion constancy and inter-subject variability in healthy individuals.

Main Methods:

• Standardization of a chemical procedure for creatinine estimation.
• Application of the standardized procedure to healthy individuals.
• Analysis of creatinine excretion rates and variability.

Main Results:

• The study standardized a chemical procedure for estimating creatinine and creatinine coefficient.
• Observed higher inter-subject variability in daily creatinine excretion.
• Found lower constancy in daily creatinine excretion for the same individual.

Conclusions:

• Creatinine excretion rate exhibits significant inter-subject variability and intra-subject inconsistency.
• Creatinine may not be a reliable indicator for extrapolating urine sample results to a 24-hour excretion rate.
• The findings question the effectiveness of creatinine normalization in reducing uncertainty in internal dose assessment for radiation workers.