Some problems in the laboratory findings in multiple myeloma.

The clinical usefulness of alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) levels in serum and pathogenetic mechanism of hypoalbuminemia and hypocholesterolemia in multiple myeloma (MM) were investigated. In cases of MM with a history of pathological fracture, the level of serum ALP was significantly higher than normal. Thus, elevated ALP in MM patients may be an indicator of the occurrence of a pathological fracture within the past 2 months. The levels of serum LDH in about 80% of the MM patients were within normal limits despite the presence of a malignant tumor. These patients showed a normal pattern of isoenzymes and more mature types according to the Greipp classification. In contrasts, the patients with elevated serum levels of LDH showed the tumor pattern of the isoenzymes and the plasmablastic type. The total cholesterol concentration was correlated with the total protein levels and the serum cholinesterase. These findings were the same as those in patients with nephrotic syndrome and polyclonal hypergammaglobulinemia without liver dysfunction. These results suggest that the decreased cholesterol in MM is due to a reduction in the synthesis of albumin in the liver.