Sae Woong Kim, et al. Table 2. Values Related to Stones in the Patients with Malig- nant Hematologic Disease Group 1 Group 2 Major Symptoms Colic pain Gross hematuia UTI Symptom free Size Locations Kidney Upper Middle Lower Treatments of Stones Conservative ESWL URSL Raiolucent Rate 7 5 2 2 4.1 3 7 2 4 6 5 1 3 4.4 2 5 2 4 8 8 6 5 1 1 33.3% 64.3% (5 / 15) (9 / 14) 44.8% (13 / 29) 34.5% (10 / 29) 10.3% (3 / 29) 17.2% (5 / 29) 4.3 17.2% (5 / 29) 41.4% (12 / 29) 13.8% (4 / 29) 27.6% (8 / 29) p = 0.02 UTI, urinary tract infection; ESWL, electric shock wave lithotripsy; URSL, ureteroscopic lithotripsy. Group I, acute or chronic leukemia; Group II, anaplastic anemia or myelody- splastic syndrome. Fig. 2. Comparison of the incidence of radiolucent stones between control and study group. Study group: patients of malignant hematologic disease. Control group: patients who visited the emergency room (p = 0.02). difference was significant (p = 0.022) (Fig. 2). DISCUSSION Howard, et al.2 reported in their study, which spanned 30 years and included over 20,000 person-years of follow-up that urolithiasis occurred in 0.9% of the pediatric acute lymphatic leukemia patients, and the incidence was much higher than otherwise healthy children and adolescents. In our study, the prevalence rate of urolithiasis for the patients with malignant hemotologic diseases was 3.2% compared to 1.4% for the general patients, and the rate was statisti- cally higher than that for the general patients. This incidence rate of stone was much higher than that Hesse A, et al.4 and Curhan, et al.4 reported (0.3-0.5%) for the general popula- tion in Western countries, and it was also higher than that reported by Kim, et al.5 (0.2%) for Koreans. We think that these differences are associated with the therapeutic methods that were used for the patients in differ- ent studies. The basis of treatment for malignant hematolo- gic diseases are chemotherapy and maintenance therapy by glucocorticoid. Sixteen of the patients who had urolithiasis had undergone chemotherapy more than once and nine of them were given additional treatments for maintenance therapy by glucocorticoid. It is presumed that chemotherapy is a risk factor for urolithiasis due to tumorlysis syndrome that often occurs during chemotherapy of patients with malignant hematologic diseases, and tumorlysis syndrome after chemotherapy often causes an increased concentra- tion of uric acid in the serum by the increasing cell damage and hemolysis.6 Glucocortcoid is widely used as maintenance therapy for the treatment of patients with leukemia because it dec- reases the leukemic blast cell count and the rate of extra- medullary infiltration.7 However, glucocorticoid therapy over a long period affects the metabolic pathway of calcium, and then it induces decreased absorption of calcium in the gastrointestinal tract and increased excretion of calcium in the urine. All of these problems can lead to urinary stone disease. Almost all the patients in the aplastic anemia and myeloplastic syndrome groups, which had a relatively higher incidence rate of urolithiasis, underwent repeated blood transfusions for symptom relief. This incidence rate was 64% of those patients who underwent blood trans- fusion 20 times before the diagnosis of urolithiasis. Most of patients with malignant hematologic diseases have compromised immunity. They are susceptible to urinary tract infection and renal dysfunction owing to urinary obstruction. Therefore, the occurrence of urolithia- sis in these patients is more morbid and complicated com- pared to general patients. Yet the urolithiais of these patients can be misdiagnosed as other diseases like gastritis, cholecystitis or hemorrhagic cystitis. Pui, et al.10 reported in their study that they enrolled 2,457 patients with acute leukemia to investigate urinary stone and non-Hodgkin’s lymphoma, and they confirmed urinary stones in only five of their patients (0.2%, 5/2457). They explained that it is possible that the urologic symptoms of urolithiasis, like flank pain and abdominal discomfort, were mistaken for neuropathy that was caused by chemotherapy or for gastritis that was caused by glucocorticoid therapy. Jaing, 246 Yonsei Med J http://www.eymj.org Volume 51 Number 2 March 2010