To the Editor.—
To determine if long-term beta carotene therapy of erythropoietic protoporphyria (EPP) had any effect on protoporphyrin levels, we have performed statistical analyses of all of the erythrocytic protoporphyrin concentrations of 44 patients with EPP who had participated for at least two years in our study of beta carotene therapy of this disease.1,2 For each patient, the data included protoporphyrin concentrations that were determined when patients were and were not ingesting beta carotene, and during summer-time (June to September) and winter-time (October to May).The level of erythrocytic protoporphyrin concentration varied widely for each patient over time and varied widely between patients. Since the values for protoporphyrin (P) were not normally distributed, but the log transformations were so distributed, the natural log transformations of the concentrations (log [RBC — P]) were used in the analysis.We first assessed the effect of the season on concentration of protoporphyrin
Miao LL, Mathews-Roth MM, Poh-Fitzpatrick MB. Beta Carotene Treatment and Erythrocytic Protoporphyrin Levels. Arch Dermatol. 1979;115(7):818. doi:10.1001/archderm.1979.04010070004007
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