Leukocytes: better known as white blood cells and help fight infection3
Granulocytes: a category of leukocytes that contain granules in their cytoplasm3
|Types of Testing|
Mixed leukocyte: This method requires isolation of leukocytes immediately after the blood is drawn.4
Granulocyte: This method requires that the whole blood sample be sent refrigerated to the lab within a certain time frame for analysis.4
It is important to remember to consult with your doctor about which test he or she recommends.
WBC cystine testing is important even if you’ve had a kidney transplant and even if you look or feel fine. Even brief interruptions in your cystine-depleting therapy allow cystine accumulation to become toxic again.6-10 The goal of cystine-depleting medications is to keep your cystine levels down, so be sure to consult with your doctor and laboratory for the recommended target values.7,11 To achieve continuous cystine control, regular WBC cystine tests may be needed as often as every 3 months and sometimes more frequently.12
The good news is that testing your WBC cystine accumulation is a procedure requiring only a blood sample.1 Because the test is so important, it’s a good idea to make regular testing a part of your cystinosis management plan. WBC cysteine testing gives you and your doctor more knowledge and information, which can enable optimal dosing and empower new strategies to help you stay one step ahead of cystinosis.
- Dalton N. The importance of accurate cystine level testing. Cystinosis Research Network Web site. https://cystinosis.org/images/research/articlelibrary/cystagon/2009_01_Cystine_Level_Testing.pdf. Published January 2009. Accessed September 23, 2016.
- National Organization for Rare Disorders. Cystinosis. NORD Web site. https://rarediseases.org/rare-diseases/cystinosis. Accessed August 20, 2016.
- Merriam-Webster: dictionary and thesaurus. Merriam-Webster Web site. http://merriam-webster.com. Accessed October 5, 2016.
- UCSD Cystine Determination Laboratory. UCSD Web site. http://cystinosiscentral.org/cystinosis/tests. Accessed September 23, 2016.
- Levtchenko E, de Graaf-Hess A, Wilmer M, van den Heuvel L, Monnens L, Blom H. Comparison of cystine determination in mixed leukocytes vs polymorphonuclear leukocytes for diagnosis of cystinosis and monitoring of cysteamine therapy. Clin Chem. 2004;50(9):1686-2688.
- Brodin-Sartorius A, Tète M-J, Niaudet P, et al. Cysteamine therapy delays the progression of nephropathic cystinosis in late adolescents and adults. Kidney Int. 2012;81(2):179-189.
- Gahl WA, Thoene JG, Schneider JA. Cystinosis. N Engl J Med. 2002;347(2):111-121.
- Gahl WA, Balog JZ, Kleta R. Nephropathic cystinosis in adults: natural history and effects of oral cysteamine therapy. Ann Intern Med. 2007;147(4):242-250.
- Levtchenko EN, van Dael CM, de Graaf-Hess AC, et al. Strict cysteamine dose regimen is required to prevent nocturnal cystine accumulation in cystinosis. Pediatr Nephrol. 2006;21(1):110-113.
- Nesterova G, Gahl WA. Cystinosis: the evolution of a treatable disease. Pediatr Nephrol. 2013;28(1):51-59.
- Gertsman I, Johnson WS, Nishikawa C, Gangoiti JA, Holmes B, Barshop BA. Diagnosis and monitoring of cystinosis using immunomagnetically purified granulocytes. Clin Chem. 2016;62(5):766-772.
- Cystinosis Research Network. Need a white blood cell cystine level? CRN Web site. https://cystinosis.org/images/family-support/resources/medical-information/CYS.WBCP.UK.pdf. Published 2009. Accessed August 21, 2016.