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Reference intervals for 24-hour and random urine porphyrins
K L Nuttall1, S S Pingree, E R Ashwood
1Department of Pathology University of Utah School of Medicine Salt Lake City 84132, USA.
Annals of Clinical and Laboratory Science
|July 1, 1996
Summary
Urine porphyrin analysis for photosensitivity can now use random samples. New reference limits based on the porphyrin to creatinine ratio simplify testing, improving accuracy for both 24-hour and random urine collections.
Area of Science:
- Clinical Chemistry
- Biochemical Analysis
- Photodermatology
Background:
- Urine porphyrin analysis is crucial for diagnosing photosensitivity disorders.
- Traditional 24-hour urine collections are cumbersome and prone to errors.
- Variability in daily porphyrin excretion necessitates reliable methods for specimen analysis.
Purpose of the Study:
- To establish reference limits for urine porphyrins using the porphyrin to creatinine ratio.
- To validate the use of random urine specimens for porphyrin analysis.
- To provide a more practical approach for evaluating photosensitivity.
Main Methods:
- Analysis of 1,171 adult urine specimens.
- Determination of uroporphyrin and coproporphyrin levels.
- Calculation of porphyrin to creatinine ratios for reference limit establishment.
Main Results:
- Established 95% reference limits for uroporphyrin and coproporphyrin relative to creatinine.
- Demonstrated applicability of these limits to both 24-hour and random urine specimens.
- Observed higher variability in random specimens compared to 24-hour collections.
Conclusions:
- The porphyrin to creatinine ratio offers a reliable method for urine porphyrin analysis.
- This method facilitates the use of random urine specimens, simplifying photosensitivity evaluation.
- New reference limits provide a standardized approach for interpreting results.