{"id":"cystatin-c","name":"Cystatin C","shortName":"Cystatin C","aliases":["Cystatin C, Serum","Cys C","CysC","Cystatin C, Immunoassay","Cistatina C","Cystatin C, Serum or Plasma","Serum Cystatin C","Cystatin-C","Cystatin C (CysC)"],"abbreviations":["CysC","Cys C","CST3"],"loinc":[{"code":"33863-2","primary":true}],"specimen":"serum-or-plasma","units":[{"ucum":"mg/L","display":"mg/L"}],"referenceRanges":[{"population":"18–49","low":0.63,"high":1.03,"unit":"mg/L","unitDisplay":"mg/L","note":"Mayo Clinic Laboratories interval for ages 18 to 49, both sexes. Labcorp prints 0.60–1.00 mg/L for ages 2 to 50, and ARUP prints 0.61–0.95 mg/L for all adults 18 and older, so labs differ slightly. Cystatin C assays are not identical across labs, so the range on your own report is the best guide. Mayo gives no range under 18 and refers to eGFR instead.","sources":[{"title":"CSTCE - Cystatin C with Estimated Glomerular Filtration Rate (eGFR), Serum","url":"https://schnecklab.testcatalog.org/show/CSTCE","publisher":"Mayo Clinic Laboratories (via the Schneck Medical Center test catalog)"},{"title":"Pediatric Testing Reference Ranges (includes Cystatin C, test 121251)","url":"https://www.labcorp.com/content/dam/labcorp/drupal/178250_DX_TL_PediatricTestRef_Final.pdf","publisher":"Labcorp"},{"title":"Cystatin and Creatinine With eGFR (test 3018316)","url":"https://ltd.aruplab.com/Tests/Pub/3018316","publisher":"ARUP Laboratories"}]},{"population":"50+","low":0.67,"high":1.21,"unit":"mg/L","unitDisplay":"mg/L","note":"Mayo Clinic Laboratories interval for ages 50 and older, both sexes. Levels tend to run higher with age. ARUP prints a single adult interval of 0.61–0.95 mg/L with no age split, so its upper limit sits below Mayo's for this age group. No published Labcorp or Quest interval for ages 50 and older was found. Because the labs differ, the range on your own report is the best guide.","sources":[{"title":"CSTCE - Cystatin C with Estimated Glomerular Filtration Rate (eGFR), Serum","url":"https://schnecklab.testcatalog.org/show/CSTCE","publisher":"Mayo Clinic Laboratories (via the Schneck Medical Center test catalog)"},{"title":"Cystatin and Creatinine With eGFR (test 3018316)","url":"https://ltd.aruplab.com/Tests/Pub/3018316","publisher":"ARUP Laboratories"}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"A small protein that nearly every cell makes and the kidneys clear from the blood, used to check kidney filtration without depending on muscle mass.","url":"https://bloodtesttracker.com/markers/cystatin-c","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}