eMedicine Specialties > Urology > Stones

Hyperuricosuria and Gouty Diathesis: Follow-up

Author: Bijan Shekarriz, MD, Director, Laparoscopy and Minimally Invasive Surgery, Associate Professor of Urology, Department of Urology, State University of New York Upstate Medical University
Coauthor(s): Marshall L Stoller, MD, Medical Director of Urinary Stone Center, Professor, Department of Urology, University of California at San Francisco; Brian H Eisner, MD, Instructor in Surgery, Department of Urology, Massachusetts General Hospital-Harvard Medical School; Fellow in Endourology, Department of Urology, University of California
Contributor Information and Disclosures

Updated: Jul 28, 2008

Follow-up

Further Outpatient Care

• All patients should undergo regular follow-up imaging studies with KUB imaging, renal ultrasonography, or unenhanced CT scanning, as indicated.
• Measuring urinary pH is important to monitor the efficacy of urinary alkalinization and to adjust medications accordingly. A repeat 24-hour urinary collection after initiation of medical therapy is beneficial. Furthermore, with any significant change in medication or diet, a repeat 24-hour urinary collection is indicated.
• Patients may titrate their own urinary alkalinization program with the aid of Nitrazine pH paper or other available pH monitoring systems. One should strive to maintain a urinary pH of 6.5-7.0. Medications may need to be adjusted during certain periods of the day.

Complications

• Untreated urinary stones may result in urinary obstruction (with or without pain) and subsequent urinary tract infection. If severe, this may result in life-threatening urosepsis. This condition requires immediate resolution of obstruction.
• In the chronic phase, recurrent obstruction and infections rarely lead to loss of renal function.
• Severe hyperuricemia may result in acute urate nephropathy in patients with myeloproliferative or lymphoproliferative disorders. The mechanism of urate nephropathy involves precipitation of urate within the renal tubules, with subsequent intratubular obstruction and severe azotemia.
• Allopurinol has been associated with the development of hemorrhagic skin lesions, exfoliation, and a rare fatal systemic vasculitis. Pruritus often precedes the development of rash and should prompt patients to discontinue the medication. Alterations in hepatic function and jaundice have been reported with allopurinol use; these complications require monitoring of serum liver function test results soon after the institution of therapy. Allopurinol may result in an acute gouty attack in patients with hyperuricemia.

Prognosis

• With appropriate medical and surgical management, the prognosis is excellent in the majority of cases.

Patient Education

• With appropriate diet and medical therapy, uric acid–related urolithiasis is a preventable disease. Patients should be instructed to maintain a daily fluid intake sufficient to generate a urinary output of at least 1.5-2 L, to avoid an excessively purine-rich diet (eg, red meat, solid-organ meats), and to limit the sodium content of their diet.
• Patients with uric acid stones should be instructed to measure their urinary pH at home with the aid of Nitrazine pH paper and to adjust their dosage of the alkalinizing agent accordingly. Generally, achieving and maintaining a urinary pH in the range of 6.5-7.0 requires a motivated and compliant patient. UriDynamics, Inc offers an improved urinary dipstick (Stone Guard 2) specifically designed for patient use to monitor urine pH. The authors usually recommend checking urine pH 3 times per day and then adjusting oral alkalinization and retesting until the daily urinary pH is in the desired range. Testing can then be reduced to once per day or even less depending on the individual’s daily variation.
• An excellent patient education book called The Kidney Stones Handbook was written specifically for patients with stones and their families by a urology expert on kidney stone disease. The authors of this article highly recommend it. The book is available from Internet online booksellers (eg, Amazon.com) or can be ordered directly from the publisher (Grant Gibbs) by calling (530) 889-1727 or emailing gsavitz@earthlink.net.
• For excellent patient education resources, visit eMedicine's Arthritis Center. Also, see eMedicine's patient education article Gout.

Miscellaneous

Medicolegal Pitfalls

• Uric acid stones are radiolucent, and noncontrast CT scanning may be required for correct diagnosis. A KUB study is also recommended to confirm that the stone visible on CT scan is indeed radiolucent and therefore likely to be composed of uric acid. Furthermore, a urinary pH level should be obtained prior to any treatment. In the case of highly acidic urine, medical treatment with urinary alkalinization should be the initial mode of treatment.

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