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[Biochemistry](https://durgical.com/en/biochemistry/) · Topic

# Plasma proteins and electrophoresis

Electrophoresis splits serum proteins into five bands; their shape helps recognise inflammation, cirrhosis, nephrotic syndrome or myeloma.

Updated 2026-11-01

## Key facts

- On agarose at pH 8.6 proteins carry a negative charge and run to the anode. Order from the anode: albumin, α1, α2, β and γ.
- Albumin: the largest band (≈ 60 %). α1: α1-antitrypsin. α2: α2-macroglobulin, haptoglobin, caeruloplasmin. β: transferrin, LDL, C3. γ: immunoglobulins.
- M spike: a narrow, tall (monoclonal) band, almost always in γ; suggests a monoclonal gammopathy (MGUS, myeloma, macroglobulinaemia).
- Polyclonal increase (broad γ band): chronic inflammation, cirrhosis, HIV infection, autoimmune disease.
- Serum has no fibrinogen; plasma shows an extra band between β and γ.

## In detail

- Normal total protein ≈ 6–8 g/dL; albumin ≈ 3.5–5 g/dL; the difference is the globulins.
- Acute inflammation: α1 and α2 rise (acute-phase proteins: α1-antitrypsin, haptoglobin, fibrinogen, CRP) and albumin falls (a negative acute-phase reactant).
- Cirrhosis: low albumin and a polyclonal γ rise with “β–γ bridging” (IgA fills the gap between the two bands).
- Nephrotic syndrome: albumin and IgG are lost in urine; α2 rises in proportion because the very large α2-macroglobulin is not filtered.
- α1-antitrypsin deficiency: a low or nearly absent α1 band.
- An M spike is confirmed by immunofixation (which heavy and light chain: IgG κ, IgA λ…) and by serum free light chains (κ/λ ratio).
- Prealbumin (transthyretin) is a faint band ahead of albumin; because it lasts about 2 days in blood, it reflects recent nutritional change.

**Also called**
Serum protein electrophoresis, SPEP, M spike

## Clinical notes

- In an older adult with bone pain, anaemia, high calcium or kidney failure, electrophoresis with an M spike points to multiple myeloma.
- Hypoalbuminaemia causes oedema through low oncotic pressure and changes the measured total calcium (corrected for albumin).
- Low haptoglobin indicates haemolysis (it binds free haemoglobin and is cleared).

## Related conditions

- [Multiple myeloma](https://durgical.com/en/conditions/multiple-myeloma/)
- [α1-antitrypsin deficiency](https://durgical.com/en/conditions/1-antitrypsin-deficiency/)
- [Amyloidosis](https://durgical.com/en/conditions/amyloidosis/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)
- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

## Related

- [Albumin](https://durgical.com/en/biochemistry/enzymes/albumin/)
- [Immunoglobulins (antibodies)](https://durgical.com/en/biochemistry/enzymes/immunoglobulins/)
- [α1-antitrypsin](https://durgical.com/en/biochemistry/enzymes/1-antitrypsin/)
- [Transthyretin (prealbumin)](https://durgical.com/en/biochemistry/enzymes/transthyretin/)
- [Amino acids: structure, charge and pKa](https://durgical.com/en/biochemistry/topics/amino-acids-structure-charge-and-pka/)
- [Isoenzymes](https://durgical.com/en/biochemistry/topics/isoenzymes/)
- [Hemoglobin variants (HbA, HbA2, HbF, HbS, HbC)](https://durgical.com/en/biochemistry/topics/hemoglobin-variants/)

## Test yourself

Think of the answer, then tap the question to see it.

## Why is albumin the band that runs furthest towards the anode?

It has a low isoelectric point and a large negative charge at pH 8.6, and it is small compared with the globulins.

## What does a narrow spike in the γ region indicate?

A monoclonal immunoglobulin made by a single plasma-cell clone: MGUS, myeloma or another gammopathy.

## Which electrophoresis pattern is typical of cirrhosis?

Low albumin and a polyclonal γ rise with β–γ bridging from IgA.

## Which band nearly disappears in α1-antitrypsin deficiency?

The α1 band, because α1-antitrypsin is its main component.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Protein electrophoresis - serum: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003540.htm) (MedlinePlus, US National Library of Medicine, 2026); [Immunoelectrophoresis – blood: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003541.htm) (MedlinePlus, US National Library of Medicine, 2026); [Total protein: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003483.htm) (MedlinePlus, US National Library of Medicine, 2026); [Free Light Chains: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/free-light-chains/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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