Serum lactate dehydrogenase and alkaline phosphatase activities and serum cholesterol level in bone marrow blood

Serum cholesterol level as well as serum lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) were measured in 65 samples of bone marrow blood and in matched peripheral blood taken from patients with various hematological diseases. As expected, serum LDH activities were higher and serum total cholesterol levels were lower in the bone marrow blood than in the blood taken from the cubital vein. More interestingly, an important increase of heat-labile ALP, but not of serum GGT, was found in the bone marrow blood obtained from patients characterized by a proliferating bone marrow. Actually, both LDH and ALP activities were obviously higher in the bone marrow blood of patients with megaloblastic anemia, myelodysplastic syndrome and chronic myeloid leukemia than in samples taken from patients with chronic lymphocytic leukemia, a disease characterized by a slower proliferation rate. While the expected increased LDH activity is the result of an accelerated turnover of bone marrow cells implying the release of this enzyme from the dividing and/or decaying cells, the much higher activity of the heat-labile alkaline phosphatase found in the bone marrow blood would reflect an enhanced local remodeling of bone structures, probably related to an expanded proliferating bone marrow. The lower serum cholesterol level in the bone marrow blood could be subsequent to an enhanced uptake of low density lipoproteins by specific receptors on the bone marrow cells.