Among the so-called autointoxications, there is a group, not very well defined, characterized by a constitutional defect which prevents the complete decomposition of certain substances. As a result, intermediate metabolic products accumulate in the blood and internal organs, and at times well defined morbid conditions, even death, may result.
Such conditions have long been known, among them being arthritis urica, diabetes mellitus, the comparatively unimportant cystinuria and alkaptonuria. The last named condition is now well known, chiefly since the appearance of a monograph by the Danish investigator Valdemar Poulsen.1 Its sequel, ochronosis (blackening of cartilage and other tissues), had already been described by Virchow, and, on account of its rarity and harmlessness, may be considered a pathologic curiosity.
Of greater practical and theoretical importance is hematoporphyrinuria, so named on account of the presence in the urine of a light reddish brown pigment, best known to occur in connection with poisoning