[Determination of coproporphyrin in urine]

Methods for urinary coproporphyrin measurements are analyzed. Data obtained by two methods, spectrophotometry and fluorescent method, are presented, the advantages and shortcomings of both are discussed. The authors recommend the fluorescent technique as a universal rapid method for wide medical practice. The problem of the units of coproporphyrin measurement is also discussed. The authors suggest replacing measurements per g of creatinine or daily portion by estimation of the coproporphyrin index in the morning portion of the urine. Study of the effects of various factors (climatic conditions, nutrition, patient's age and sex) on normal coproporphyrin excretion from the body has demonstrated that these factors do not noticeably influence porphyrin metabolism; for normal subjects the coproporphyrin index varies from 30 to 110 micrograms/day.