Correlation of serum and urinary porphyrin levels in porphyria cutanea tarda.

A significant linear correlation was found between serum total porphyrin concentration and 24-hour total urinary porphyrin excretion in 18 patients with porphyria cutanea tarda sampled at diagnosis and during and after treatment on 73 occasions. This confirms that the serum porphyrin level parallels urinary porphyrin excretion and is an appropriate indicator of disease activity useful for monitoring patients in clinical practice.