Serum lactate dehydrogenase isoenzyme-1 in children with yolk sac tumor.

Although in recent years the evidence of an increase in serum lactate dehydrogenase isoenzyme-1 (LDH-1) in patients with germ cell tumor (GCT) has attracted attention, there have only been a few reports concerning yolk sac tumor (YST), which is a frequent type of GCT in childhood. Serum LDH isoenzymes were determined in eight children with YST, and an increase in LDH-1 was found in seven of them, excluding one in an early stage. On the basis of the findings of serial serum LDH-1 levels during treatment and of LDH isoenzyme pattern in tumor tissues, it is presumed that the increased serum LDH-1 is derived from tumor tissues. LDH-1 seems to be useful as a tumor marker, not specific for YST but associated with the whole spectrum of GCT, for monitoring of YST.