Measurement of urinary porphyrins and porphyrin precursors in Dutch hospital laboratories: a review of quality control over 5 years

Abstract

Background: We evaluated a quality control scheme for the measurement of urinary uroporphyrin, coproporphyrin, total urinary porphyrins and precursors of urinary porphyrins, delta-aminolevulinic acid and porphobilinogen that was performed in The Netherlands during a period of 5 years.

Methods: Six quality control samples were distributed each year to the participating laboratories. Mean concentrations and the corresponding coefficients of variation were calculated.

Results: Coefficients of variation varied widely and were very high in the concentration ranges that can be found in patients with low-grade porphyria.

Conclusion: Commutable calibrators are needed to improve the laboratory diagnosis of porphyria.