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SUMMARY Twenty men and one woman with porphyria cutanea tarda were treated with oral chloroquine, 125 mg twice weekly. In nineteen of the patients chloroquine was taken for 8–5 months on average before complete clinical and biochemical remission occurred. Initially, treatment led to a considerable increase in urinary uroporphyrin and a mild increase in serum transaminases, but no adverse clinical reactions were observed. As the mechanism of chloroquine action in porphyria cutanea tarda has not yet been clarified, special caution must be observed when it is used therapeutically.

In three patients with attacks of acute intermittent porphyria we found markedly impaired functions of the left ventricle accompanied by ECG changes that returned to normal after administration of heme arginate or cytochrome C administration. In nine patients with other types of porphyria, and in one patient with acute intermittent porphyria not suffering an attack, no significant changes of left ventricle function were observed. The changes seen in patients with an acute attack may be ascribed to acute myocardial hypoxia resulting from defective biosynthesis of heme. We assume that the exogenous supply of heme may improve cellular hypoxia.

Porphyrinogens were determined in very fresh, diluted morning urine in two types of hepatic porphyria, using a simple and very quick spectrophotometric method. It was shown that acidification by itself is insufficient for the complete conversion of colourless porphyrinogens into porphyrins in photometric determination of porphyrins in diluted urine. A correlation was shown between percentual content of porphyrinogens and the sum of pentacarboxyporphyrin and coproporphyrin. A difference was found between the excretion of porphyrinogens in morning fresh urine in porphyria cutanea tarda (average porphyrinogen fraction 22.5%, SD 10.3% of total porphyrins) and in acute intermittent porphyria (average porphyrinogen fraction 77.1 %, SD 9.3% of total porphyrins). The method is at the same time suitable for the detection of urobilinoids in urine. Oxidation of the urine in acute intermittent porphyria is recommended before adsorption on talc and subsequent thin j layer chromatography, because porphyrinogens are not adsorbed on talc.

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