Porphyrin metabolism in secondary hepatic porphyria in patients with hereditary deficiency of glucose-6-phosphate dehydrogenase

Abstract

Aim. The study the porphyrin metabolism during the development of secondary hepatic porphyria in patients with glucose-6-phosphate dehydrogenase deficiency. Methods. Examined were 148 male patients aged 5-19 years (median 12 years) with impaired activity of glucose-6-phosphate dehydrogenase in combination with β-thalassemia and without it. Qualitative and quantitative methods of examining the activity of this enzyme were used in order to verify the diagnosis. Taking into account the varying degree of glucose-6-phosphate dehydrogenase deficiency, the indices of metabolism of the enzyme and of the porphyrins were correlated with the severity of anemia, functional liver capacities, with parameters reflecting iron content in blood serum, bone marrow, liver and urine. The markers of intoxication were also taken into account in the development of secondary hepatic porphyria and endotoxemia. Therapeutic plasmapheresis was used to correct the revealed disorders. Results. The influence of glucose-6-phosphate dehydrogenase deficiency on the metabolism of porphyrins and liver functional status has been shown, which leads to the development of anemia and endogenous intoxication. With the help of parameters, which characterize the porphyrin metabolism in patients, secondary hepatic porphyria was revealed. It was established that determination of the content of glucose-6-phosphate dehydrogenase and porphyrins makes it possible to detect disturbances in heme synthesis at an early stage and to evaluate the compensatory abilities of the liver. An important diagnostic feature for glucose-6-phosphate dehydrogenase deficiency, regardless of severity, is the impaired synthesis of the end products of metabolism of porphyrins - uro-, copro- and protoporphyrin. The effectiveness of therapeutic plasmapheresis for hemolysis, secondary hepatic porphyria and endogenous intoxication has been shown. Conclusion. Increased excretion of uro-and coproporphyrin with urine reflects the severity of endotoxemia, and is an alternative to markers of intoxication; high concentration of free protoporphyrin and low concentration of uro- and coproporphyrin in erythrocytes is an important diagnostic sign of impaired activity of glucose-6-phosphate dehydrogenase in patients.