6402: Cystine Capacity (CysCap) Study

Status: Closed



Cystinuria is a condition that is passed down in families. In cystinuria, there is an abnormality in the way the kidneys handle cystine (an amino acid), such that there is too much cystine in the urine. Cystine, when present in high concentrations, crystallizes to form cystine stones. Our study aims to determine if a test called Cystine Capacity (called “CysCap”) will accurately predict whether or not stones will form.

Current methods do not predict stone recurrence well enough to tailor therapies for people affected by cystinuria. The development of a new test by Litholink Corporation, called CysCap, measures the concentration of cystine of a patient’s urine. This test may provide a measurement that will potentially predict recurrence of stones and use that information to guide therapy. Tailoring therapies to the individual patient increases the effectiveness of treatment and minimizes its side effects. Cystinuria varies greatly from person to person. Some patients have mild disease with few stones in their lifetime while others experience frequent stones which require many treatments (including urologic procedures) per year. Overall, we anticipate that customizing treatment for the individual will improve the treatment and quality of life for patients with cystinuria.

The ability to reliably predict stone recurrence may be valuable in the management of your condition and possibly lead to changes in the treatment of future patients. Physicians will be able to make dietary and pharmacological (medication) modifications tailored to your urine test findings. We are hoping to enroll 30 patients per year for the duration of this study. Currently this study will be done at Lenox Hill Hospital, Manhattan and Wake Forest University School of Medicine.

About this Study

This study involves:

  1. A screening interview. In your first visit, researchers will ask about the history of your cystinuria, medications you take, and your dietary habits. We will review any recent radiology (x-rays, ultrasound or CT scans) findings and discuss any recent urologic procedures you may have had. The total time for this visit should be approximately 30 minutes.
  2. A 24-hour urine collection. At the end of the visit, we will ask you to perform a 24-hour urine collection to measure urinary cystine levels. We will provide all of the materials needed to perform this collection and will have it sent to Litholink, the laboratory that will perform the analysis of your urine, at no cost to you.
  3. Radiologic imaging (testing). You will also be asked to have radiologic imaging (testing) performed (either x-ray, ultrasound or CT scan) if it is part of your normal course of care. The type of imaging done will be at the discretion of your primary nephrologist or urologist.
  4. Follow-up visits every 6 months. You will have follow-up visits every 6 months for the length of the study (up to 3 years).
    1. Follow-up visits will include a review of any events (such as urologic procedures and episodes of stone passage), changes in medications and dietary habits. These visits will typically be shorter, approximately 20 minutes.
    2. After each visit, you will be asked to perform a 24-hour urine collection and radiologic imaging. Results of the laboratory tests and radiologic imaging will be provided to your primary nephrologist or urologist. With this information, your primary nephrologist or urologist may decide to change their treatment strategies if the tests suggest they should do so. However, this study does not require that the management of your cystinuria be changed in any way.

Targeted Enrollment

To be eligible to participate, you must:

  • Have a confirmed laboratory diagnosis of cystinuria that meets the following criteria:
    • Stone analysis demonstrating cystine as a component
    • Increased urinary cystine excretion (>250 mg/24 hours in adults and >250 mg/gm creatinine in children).
  • Be able to reliably collect urine for 24 hours.
  • Be willing and able to adhere to study follow-up requirements.
  • Be able to provide an informed consent document if you are over 18 years of age. Children 8-18 years of age will be required to sign an assent to participate, in addition to parental consent.

You are not eligible to participate if you are not:

  • Willing or able to provide consent or assent.
  • Able to reliably collect urine for 24 hours.
  • Willing able to adhere to study follow-up requirements.

How to participate

In order to participate in a study, you must personally contact the study coordinator of any of the participating institutions by phone or by e-mail. Please use the information below to inquire about participation.

United States


University of Alabama at Birmingham
Contact: Ralee’ Bishop Bunt
Phone: 205-934-2272
E-mail: erikabunt@uabmc.edu

New York

New York University, New York City
Contact: Frank Modersitzki
Phone: 212-686-7500 Ext: 6379
E-mail: Frank.Modersitzki@nyumc.org