Elevated SM accumulation is defined as 4 to 6 times normal SM accumulation with normal enzyme activity. Niemaoh-Pick disease (NPD), also known as sphingomyelin lipidosis, is a congenital disorder of glycolipid metabolism. It is characterized by elevated serum mucin (SM) accumulation. What are the tests for elevated SM accumulation? The following is an explanation for you. 1, hemogram hemoglobin is normal or with mild anemia; leukocyte reduction is apparent in hypersplenism. Monocytes and lymphocytes often show characteristic vacuoles, about 8 to 10, which have diagnostic value. On electron microscopy, these vacuoles are lipid-filled lysosomes. The platelet count is normal, with advanced hypersplenism and decreased time to significant bone marrow invasion. The patient’s leukocytes lacked neurophospholipase activity. 2. The bone marrow picture contains typical neuro-slow-pick cells, often called foam cells, with nuclei 20-100 μm in diameter; small, round or ovoid nuclei, usually single, but may also have double nuclei; abundant cytoplasm, filled with round droplet-shaped clear vesicles, resembling mulberry or foam. The electron microscopy showed that the vesicles were surrounded by a partial membrane layer structure. Examination of unstained specimens with a bitemporal microscope showed small bubble-like cells in the cytoplasm, unlike Gaucher cells. Under polarized light, the vesicles are birefringent; under ultraviolet light, the fluorescence is greenish-yellowish. Biochemical characteristics PAS reaction is weakly positive, the wall of the vesicles in the cytoplasm is positive, the center of the vesicles is negative; acid phosphatase, alkaline phosphatase, Sudan black are negative reaction. 3. Plasma cholesterol and total lipids may be elevated, and SGPT is mildly elevated. 4. Urinary excretion of neurosphingomyelin is significantly increased. 5, liver, spleen and lymph node biopsies have heaped, patchy or diffuse foam cell infiltration, neurosphingomyelin. In long-term surviving cases, due to the proliferation of lipid-filled histiocytes in the bones, there may be osteoporosis, widening of the medullary cavity, thinning of the bone cortex, and even focal areas of destruction in the long bones, but there is no skeletal expansion deformity. After infancy, the alveoli are infiltrated by lipid-filled histiocytes, and lung manifestations similar to histiocytic hyperplasia X are seen. In conclusion, it is non-specific and only provides a basis for auxiliary diagnosis. 7, Determination of leukocyte or cultured fibroblast sphingomyelinase activity, the activity of each type of enzyme varies.