title: Absence of circadian variations in urinary porphyrin excretion in normal subjects.
abstract: The hypothesis that urinary porphyrins could be excreted in a circadian rhythm was examined. A group of 20 healthy subjects, 10 males and 10 females, aged 20-40 years, were used in this study. Urine was collected at 4-hr intervals over three 24-hr periods. Median porphyrin concentrations (microgram l-1 or microgram g-1 of creatinine) were similar in the six groups, but significant differences were observed in that excreted. Highest porphyrin excretion was detected in the afternoon (12.00-16.00 hr) and, in the evening (16.00-20.00 hr). pH values were also increased at evening but did not correlate with porphyrin excretion. Despite these temporal variations, no cycles indicating circadian periodicity were observed. Therefore, a 24-hr collection of urine is not necessary for the initial evaluation of porphyrin metabolism.
authors.affiliation: Prophyria Unit, Hospital Universitario Doce de Octubre, Madrid, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Enriquez de Salamanca
authors.forename: A
authors.initials: A
authors.lastname: Hernandez
authors.forename: P
authors.initials: P
authors.lastname: Sepulveda
authors.forename: M J
authors.initials: MJ
authors.lastname: Moran
mesh_terms: D000328:Adult; D000622:Aminolevulinic Acid / Q000652:urine; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D011162:Porphobilinogen / Q000652:urine; D011166:Porphyrins / Q000652:urine*
chemical_list: D011166:Porphyrins; D011162:Porphobilinogen; D000622:Aminolevulinic Acid