A porphyrin-soaked diaper

To the Editor: The superb photographs of a diaper soaked with urine containing a high porphyrin level (Jan. 13 issue)¹ warrant additional clarification so as not to mislead readers¹. No specific diagnosis beyond porphyria is given, and it should be understood that fluorescence of a diaper under Wood's light, as shown in the image, is typically encountered only in congenital erythropoietic porphyria (Gunther's disease), which is one of the rarest porphyrias². Since this test or observation is of no value in the other porphyrias, detailed diagnostic tests have to follow the initial suspicion in order to ascertain the.