American Journal of Clinical Nutrition, Vol 22, 1290-1303, Copyright © 1969 by The American Society for Clinical Nutrition, Inc.

Zinc in Porphyria

¹ Head of Division of Biochemistry, Institute of Medical and Veterinary Science, Box 14, Rundel Street Post Office, Adelaide, South Australia 5000

Very few data are available for the excretion of zinc in urine and zinc levels in serum and plasma in human subjects, as reliable methods have been developed only recently. These results have been tabulated for normal persons and show that the normal zinc excretion is of the order of 100-900 µg Zn/24 hr, but that this may be affected by food intake and is increased in a number of diseases, being highest in periarteritis nodosa, followed by organic brain syndrome, and then alcoholism. The excretion in porphyrics is very high in patients with acute intermittent porphyria but may be below normal in some forms of cutaneous porphyria.

The normal serum and plasma levels of zinc are approximately the same and of the order of 100 µg Zn/100 ml. This level again can show physiological variations due to food intake and pregnancy and varies considerably in neonates and young children. Liver disease, especially alcoholic cirrhosis, lowers the serum zinc, whereas in porphyrics with cutanea tarda and who are alcoholics serum zinc levels are high. Serum zinc levels are also very high in patients severely ill with acute intermittent porphyria and both the serum and urinary zinc levels increase with the severity of the disease. In no other disease have such high serum or plasma zinc levels been reported.

Though zinc is not etiologically connected with porphyria, there is a secondary link. Some symptoms seen in porphyrics are possibly due to local zinc deficiency in particular tissues caused by the complexing of zinc required for some metalloenzymes by excess porphyrins present.

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