Norm of Sphingomyelinase

1.53–7.18 U/g.
Not clinically significant.
Colitis (chronic), Niemann-Pick disease, types A and B.


Description of Sphingomyelinase

Sphingomyelinase is an enzyme that acts as a catalyst in the metabolism of sphingomyelin. Sphingomyelin is a phospholipid ubiquitously distributed in all membranes of mammalian cells and in serum lipoproteins. Niemann-Pick disease is an autosomal recessive lysosome storage disease caused by sphingomyelinase deficiency. Massive tissue accumulation of sphingomyelin results. Two types of Niemann-Pick disease have been identified: type A is a severe, neurodegenerative infantile form leading to death by 4 years of age; and type B is a chronic, nonneuronopathic form. A subacute form, similar to type B but with mild neuronal involvement (retinal storage, peripheral neuropathy, mild neurologic changes, or psychiatric disorders), has also been identified. In this test, a skin biopsy is used to perform fibroblast tissue culture and fibroblast assay for sphingomyelinase activity.


Professional Considerations of Sphingomyelinase

Consent form NOT required.

  1. Obtain a skin punch biopsy setup and a sterile plastic cup.



  1. Cleanse the biopsy site with alcohol and allow it to air-dry.
  2. Obtain a skin punch biopsy with a 4-mm punch.


Postprocedure Care

  1. Place the biopsy specimen in a sterile cup.


Client and Family Teaching

  1. A mild analgesic may be used for site tenderness.
  2. Contact the physician for redness, swelling, increasing tenderness, purulent drainage, or slow healing noted at the site.
  3. Genetic counseling must be provided for individuals and families undergoing genetic testing.


Factors That Affect Results

  1. Inadequate punch biopsy specimen may cause false-negative results.


Other Data

  1. Timeliness of results depends on laboratory availability.