Days Set Up
Monday - Thursday
Analytic Time

10 - 14 days

MiChart Code
Cystine, Leukocytes (MMGL)
Soft Order Code

Test Updated:


Cystine, Leukocytes
Cystine, Leukocyte
White blood cell cystine
Leukocyte Cystine Shadow
Leukocyte Preparation

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Find a Requisition

All specimens should be accompanied by a requisition.

Submitting Specimens

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MLabs provides all the supplies necessary for the collection of specimens.

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Test Overview

Test Methodology

Competitive protein binding assay.

Test Usage

The intracellular cystine content of acid-stabilized white blood cells may be used to evaluate the cystine-depleting effect of Cystagon or to diagnose (or rule out) new cystinosis patients. White cells are used because cystine is not elevated in red cells or plasma of cystinosis patients. (It is elevated in urine also, but this is not diagnostic.) The normal value is generally less than 0.2 nmol half cystine/mg white cell protein. The cystinosis value is generally greater than 2 nmol half cystine/mg white cell protein.

Reference Range

Interpretive report provided.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements

Collection Offsite

Contact MLabs Client Services Center prior to collection of specimen for instructions regarding sample preparation or to confirm that UMHS specimen processing tech will be available. Blood must be collected 5-6 hours after a dose of Cystagon and processed immediately for the white cell cystine measurements to be meaningful.

Normal Volume
5 mL whole blood
Minimum Volume
3 mL whole blood

Billing Information

CPT Code
Pro Fee Code

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Our High Standard

Quality that sets us apart

As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.