{"id":"m-protein-serum","name":"M-Protein (Monoclonal Spike), Serum","shortName":"M-spike","aliases":["M-Spike","M Protein","Monoclonal Protein","Monoclonal Spike","M-Component","Paraprotein","M-Protein Quantitation","M-Protein, Serum","Monoclonal Protein, Serum","Serum M-Spike","Serum Monoclonal Protein","Monoclonal Protein Quantitation","Quantitative M-Protein","Monoclonal Spike (M-Spike)","Monoclonal Component","M-Band","Paraprotein, Serum"],"abbreviations":["M-spike","M-protein"],"loinc":[{"code":"33358-3","primary":true},{"code":"104837-0","primary":false},{"code":"51435-6","primary":false},{"code":"35559-4","primary":false}],"specimen":"serum","units":[{"ucum":"g/dL","display":"g/dL"},{"ucum":"g/L","display":"g/L"}],"referenceRanges":[{"population":"Adults","low":null,"high":0,"unit":"g/dL","unitDisplay":"g/dL","note":"ARUP prints the reference interval for monoclonal protein as '<=0.00 g/dL', which means no M-spike is seen. Many labs print 'not detected' instead of a number. Mayo's MASS-FIX study likewise reports a negative flag with 'No monoclonal protein detected'. This is a 'none expected' limit, not a spread of healthy values: small monoclonal proteins are found in about 3% to 6% of adults over 50 and are often harmless (Leukemia 2025 review).","sources":[{"title":"Protein Electrophoresis, Serum (test 0050640)","url":"https://ltd.aruplab.com/Tests/Pub/0050640","publisher":"ARUP Laboratories"},{"title":"Protein Electrophoresis with Reflex to Immunofixation, Serum (test 2002109)","url":"https://ltd.aruplab.com/Tests/Pub/2002109","publisher":"ARUP Laboratories"},{"title":"Monoclonal Protein Study, Expanded Panel, Serum (test 2002715)","url":"https://ltd.aruplab.com/Tests/Pub/2002715","publisher":"ARUP Laboratories"},{"title":"QMPSS - Overview: Monoclonal Protein Study, Quantitative, Serum","url":"https://www.mayocliniclabs.com/test-catalog/overview/620919","publisher":"Mayo Clinic Laboratories","year":2025}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"The size of a monoclonal protein (M-spike), a single antibody made by one group of plasma cells. Most people have none.","url":"https://bloodtesttracker.com/markers/m-protein-serum","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}