Measurement of Urinary Porphobilinogen and Porphyrins: Preliminary Data from a Pilot QA Scheme

Allen, K R; Rushworth, Parker; Degg, T J; Barth, JH

doi:10.1177/000456329703400512

Cited by 8 publications

(1 citation statement)

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“…A recent paper described the performance of HPLC methods for measurement of total urine porphyrin concentration in seven laboratories participating in the Yorkshire Regional Analytical Committee (7). Coefficients of variation of porphyrin measurements in different patient samples analysed in these laboratories varied between 6% and 26% (inter-laboratory results).…”

Section: Introductionmentioning

confidence: 99%

On Accuracy and Precision of a HPLC Method for Measurement of Urine Porphyrin Concentrations

Zuijderhoudt

Koehorst²,

Kluitenberg³

et al. 2000

CCLM

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We studied the accuracy and precision of a HPLC method for determination of porphyrins in urine. A commercial standard solution appeared to contain less porphyrins than indicated by the manufacturer, since calibration resulted in lower concentrations of uroporphyrin and coproporphyrin: 16% and 8%, respectively. Coefficients of variation for the measurement of uro-, hepta-, copro I and copro III porphyrins in samples of patients with and without porphyria were often much less than 15%. Comparison of measurements with and without calibrated standards revealed differences for uroporphyrin and coproporphyrin of 27% and 5%, respectively. Recovery of added uroporphyrin and coproporphyrin was 99%. The main cause of the variability in test results was apparently the improperly calibrated standard solutions. The precision of porphyrin measurements was not influenced by the type of porphyria.

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Section: Introductionmentioning

confidence: 99%