What is the reference range for serum protein electrophoresis (SPEP)?

Updated: Jul 31, 2019
  • Author: Sherilyn Alvaran Tuazon, MD; Chief Editor: Eric B Staros, MD  more...
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Answer

Answer

Serum protein electrophoresis (SPEP) is an easy, inexpensive method of separating proteins based on their net charge, size, and shape. The 2 major types of protein present in the serum are albumin and the globulin proteins. Albumin is the major protein component of serum and represents the largest peak that lies closest to the positive electrode. [1] Globulins comprise a much smaller fraction of the total serum protein but represent the primary focus of interpretation of serum protein electrophoresis. Five globulin categories are represented: alpha-1, alpha-2, beta-1, beta-2, and gamma, with the gamma fraction being closest to the negative electrode.

Adults/elderly

Reference ranges are as follows [2] :

  • Total protein - 6.4-8.3 g/dL or 64-83 g/L (SI units)
  • Albumin - 3.5-5 g/dL or 35-50 g/L (SI units)
  • Globulin - 2.3-3.4 g/dL
  • Alpha-1 globulin - 0.1-0.3 g/dL or 1-3 g/L (SI units)
  • Alpha-2 globulin - 0.6-1 g/dL or 6-10 g/L (SI units)
  • Beta globulin - 0.7-1.1 g/dL or 7-11 g/L (SI units)

Children

Total protein

Reference ranges are as follows [2] :

  • Premature infant - 4.2-7.6 g/dL
  • Newborn - 4.6-7.4 g/dL
  • Infant - 6-6.7 g/dL
  • Child - 6.2-8 g/dL

Albumin

Reference ranges are as follows [2] :

  • Premature infant - 3-4.2 g/dL
  • Newborn - 3.5-5.4 g/dL
  • Infant - 4.4-5.4 g/dL
  • Child - 4-5.9 g/dL

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