Case Studies in Cystinuria

David S. Goldfarb, MD; Michael Grasso, MD

Disclosures

Urol Nurs. 2017;37(2):90-93. 

In This Article

Case Study 1

Patient J.O., currently 42 years of age, consulted our practice seeking additional information about and optimal care of her rare kidney stone disorder. At the time of presentation, she had a long and complicated medical and kidney stone history.

At the age of 13 years, she had sudden onset of sharp pain in her back and lower abdomen that worsened over a short period of time. She described an inability to find a comfortable position, nausea, vomiting, and intense sweating, and was brought to the emergency room with concern for ruptured appendicitis. In the emergency department, an abdominal X-ray revealed a right-sided ureteral stone 4 mm in diameter. She was told to take pain medication and was sent home for the stone to pass and be collected.

J.O.'s pain resolved, presumably representing passage of the stone. However, the stone was not recovered. She remained without incident until age 22, when she presented to the emergency department with the same symptoms as in the previous episode. The stone was collected and sent to the appropriate laboratory to determine its composition by X-ray crystallography. The stone composition was 100% cystine, and a diagnosis of cystinuria was made.

Clinical Interaction

J.O. was referred to a urologist and was told to increase her fluid intake. She was prescribed sodium bicarbonate and potassium citrate to be taken by mouth daily. Unfortunately, she was not counseled or did not understand she had a genetic stone disorder, which could lead to chronic and recurrent stone production. She continued to produce one to two stones per year, and at age 24, had multiple failed extracorporeal shock wave lithotripsies. Her surgeon proceeded with ureteroscopy, which was successful in making her stone-free.

Postoperatively, no changes were made to her medication regimen, and 24-hour urine testing was not considered. The pattern of passing one to two stones per year continued until age 30, when the patient began passing small fragments daily and experiencing chronic low-grade pain. She was found to have large bilateral stones requiring her first percutaneous nephrolithotomy (PCNL) procedure. Over the next four to five years, J.O. was in and out of the hospital with multiple pain episodes due to obstructing stones, some of which required urologic interventions.

In 2007, J.O. visited a new urologist, who performed her first 24-hour urine collection and noticed that the patient's cystine concentrations remained high despite attempts to increase fluid intake and alkalinize her urine. She was prescribed tiopronin (Thiola®) 200 mg twice daily, and was instructed to limit her sodium and protein intake. The urologist also provided J.O. with information regarding cystinuria as a genetic disorder.

Results of Clinical Interaction

J.O. described feeling optimistic about being offered a new drug for stone prevention. She also changed her diet and significantly increased her fluid intake. J.O. continued to follow up with the urologist for the next nine years. During that time, she had fewer stone episodes, but still continued to have at least one surgery per year and experienced chronic pain treated with opiates as needed. She was told that this type of lifestyle is expected, and it would be unlikely for her to become stone-free. She does not recall having more than one additional 24-hour urine collection during this time period. During her lifetime, J.O. underwent approximately 50 urologic procedures.

In mid-2015, J.O. interacted with the International Cystinuria Foundation, where she learned more about cystinuria and received a more detailed explanation regarding the use of tiopronin and the steps needed to become stone-free. Specifically, it was suggested that she see a local urologist who had more experience with cystinuria. She learned she may benefit by having her tiopronin dose adjusted so it would lower her cystine levels below the solubility limit (as per the prescribing information for tiopronin).

Two months later, the new urologist repeated J.O.'s 24-hour urine collection and detected persistently high concentrations of cystine. This finding justified an increase in her tiopronin dose to 600 mg three times daily. J.O. now reports little to no daily stone fragments in her urine, far less pain, and feeling better overall. Continued follow up on the patient's daily quality of life and results of imaging studies to assess her stone production are needed. More frequent 24-hour urine testing should be continued to assess her response to medication therapy and dietary management.

Clinical Implications

As described earlier, J.O. has had multiple surgeries. She describes developing chronic pain in her flank and back at the site of the surgeries. Fortunately despite all of these episodes of obstruction and procedures, she still has normal kidney function. J.O. takes medications daily for her disease and tolerates these drugs well (effects of cystinuria specific medications vary from patient to patient).

J.O. has not always had the attentive care she desires and deserves. She has had many occasions where healthcare providers did not recognize the chronicity and recurrence of cystinuria. Further, her chronic pain was often downplayed and not always taken seriously if an obstructing stone was not seen on imaging studies. Under-standing the chronic nature of cystinuria and recognizing that these patients have real pain may help improve the quality of care for patients with cystinuria (Modersitzki, Pizzi, Grasso, & Goldfarb, 2014).

J.O. struggles with chronic renal, back, and flank pain. She finds it difficult to plan for personal events and suffers from anxiety as a result. Her pain affects her ability to be a reliable parent and wife. Cystinuria has had a major impact on her quality of life.

Conclusion

This case describes an unfortunate but common situation for patients living with cystinuria, who are often under-informed about their disease and eagerly seek more information. In some cases, patients may be undergoing medical management but have not had adequate follow up with 24-hour urine collection to assess cystine levels and the effectiveness of their therapy. Patients are often not offered tiopronin when needed or are prescribed doses lower than the 800 mg/day as recommended in the prescribing information. J.O.'s experience and other similar patient histories lead to some critical conclusions about the management of cystinuria. To achieve success in the treatment of cystinuria, it is necessary to educate patients about their disease, review their stone history to determine appropriate medical management, and monitor patients adequately to assess the effectiveness of therapy, with the goal of rendering patients stone-free.

processing....