Urinary total porphyrins by ion exchange analysis: reference values for the normal range and remarks on preformed prophyrins in acute porphyria urine.

Abstract

SUMMARY Determination of total porphyrin with a rapid and easy method (ion exchange; spectrophotometry) was performed on 57 morning urine samples from laboratory personnel, 59 arbitrary day urine samples from blood donors, and 90 24-hour urines from medical inpatients. The upper reference limit for morning urine was 0'32 ,tmol/1 but even a value as high as 0 7 ,umol/l was found.In the donor urines the upper limit was 0-155 tkmol/l. The 24-hour urines showed an upper reference limit of 271 ug/24 h. These values are in good agreement with values from the literature, mostly based on extraction analyses. Tracings of the absorption curves in the region of 380-430 nm were performed in all analyses and showed that the non-porphyrin absorption was close to linear in most cases. Studies of porphyric urines gave no support to the claim that preformed porphyrins not formed from porphobilinogen are excreted in this disease.The reference values for urinary porphyrins in the normal range found in the literature are based on various techniques, but primarily on rather timeconsuming solvent extraction methods, while satisfactory reference materials based on the more rapid and simple ion exchange analysis have not been presented. As we have recently (With and Pedersen, 1978) described an easy, rapid, and cheap ion exchange technique for the determination of total porphyrin in urine, we collected reference material of blood donors, laboratory personnel, and medical inpatients with this technique and included tracings of the absorption curve in the range 380-430 nm to get the best possible check on analytical accuracy.We also included 10 patients with latent porphyria (acute intermittent type) from our material (With, 1969)