JOURNAL OF ENDOUROLOGY Volume 27, Number 12, December 2013 ª Mary Ann Liebert, Inc. Pp. 1539–1542 DOI: 10.1089/end.2013.0236
Urinary Stone Composition in Israel: Current Status and Variation with Age and Sex—A Bicenter Study Kalba D. Usman, MD,1,* Shay Golan, MD,1,* Tamer Abdin, MD,2 Pinhas M. Livne, MD,1 Dov Pode, MD,2 Mordechai Duvdevani, MD,2 and David Lifshitz, MD1
Abstract
Background and Purpose: The epidemiologic data regarding stone composition in Israel are based on anachronistic methods of stone analysis. Historically, Israel was noted for an unusually high percentage of uric acid stones. The aim of the study was to describe the current stone composition distribution in Israel, using modern techniques of urinary stone analysis. Age and sex correlations were investigated. Materials and Methods: In a bicenter study, using infrared spectroscopy and X-ray diffraction, stones from five hundred and thirty eight (538) patients were analyzed and demographic data recorded. Results: The study cohort included 401 men (74.5%) and 137 women (25.5%) with a male to female ratio of 2.9:1 and a median age of 48 years (range 2–85 years). While calcium oxalate monohydrate was the predominant component in both sexes, it was lower in female patients (77.3% vs 65%). The rate of infection stones (struvite + carbonate apatite) was significantly higher in women (35.7% vs 10.2%). Uric acid stones were found in only 14.5% of the patients and increased with age. Conversely, the rate of calcium oxalate dihydrate decreased with age. Conclusions: Modern techniques of urinary stone analysis showed that the most frequent stone component in Israel is calcium oxalate monohydrate. In contrast to earlier reports and in accordance with reports from other countries, the overall frequency of uric acid is 14.5%. With age, the frequency of uric acid increases reaching 21% in persons > 60 years old. A significant sex difference was noted in the distribution of calcium oxalate stones and infection stones. The classic 3:1 ratio was maintained, however. Introduction
U
rolithiasis is a common disease throughout the world. Regional differences attributed to factors such as climate and diet are noticeable, however. Although higher prevalence of stone disease is found in hot or dry climates. it seems that genetic and dietary factors may offset the climate effect. For example, the reported prevalence of stone disease in Asia, between 1% and 5%,1 is lower than the recently reported prevalence in the United States of about 9%.2 Dietary changes may also be responsible for the steady increase of stone disease during the last 5 decades as well as for the decrease in the male to female ratio.3 Furthermore, changes in stone composition are noted with a higher prevalence of uric acid (UA) stones associated with increasing body mass index.4 Israel geographically belongs to the Mediterranean stone belt,5 while demographically, its population comprises various ethnic groups that have immigrated from different regions of the world. Many persons as well as substantial
groups underwent a change of profession, social status, and climatic environment. The above conditions made Israel an interesting country as far as the study of epidemiology of urolithiasis is concern. Earlier studies from Israel, often quoted in urology textbooks, noted an unusually high prevalence of UA stones reaching up to 40%.6 These studies, however, were based mostly on chemical stone analysis. The purpose of our study was to examine the current stone composition in Israel using modern stone analysis techniques. Data from two tertiary centers located in different geographical regions (Tel Aviv area and Jerusalem) were obtained to overcome regional differences. In addition to the overall frequency of different stone components, we investigated the sex and age distributions. Patients and Methods Over a 1-year period, stones from 538 patients were analyzed. The stone samples were retrieved during endoscopic
1
Rabin Medical Center, Petach Tikva and Sakler Tel Aviv University Sackler School of Medicine, Petah Tikva, Israel. Hadassah Hebrew University Hospital, Jerusalem, Israel. *Authors have equal study contribution. 2
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USMAN ET AL.
Table 1. Distribution of Patients, Procedures, and Stone General Characteristics
Table 2. Occurrence Frequency of Stone Components and Homogeneity
Characteristic Stone component Age Mean (range) Median (IQR) Sex, n (%) Female Male Procedure, n (%) Ureteroscopy PCNL SWL RIRS Cystolithotripsy Spontaneous evacuation Stone homogeneity, n (%) Pure stones Mixed stones
48 (2–85) 50 (38, 58) 137 (25.5) 401 (74.5) 279 149 54 28 9 18
(51.8) (27.7) (10) (5.2) (1.7) (3.3)
Calcium oxalate monohydrate Calcium oxalate dihydrate Calcium phosphate Uric acid Carbonite-apatite Magnesium ammonium phosphate (struvite) Calcium hydrogen phosphate dihydrate (brushite) Cystine
Total number (%)
Mixed (%)
Pure (%)
399 (74.2)
309 (57.4)
90 (16.7)
183 (34)
165 (30.6)
18 (3.3)
197 78 67 23
188 30 64 22
9 48 3 1
(36.6) (14.5) (12) (4.1)
(34.9) (5.5) (11.9) (4)
(1.6) (8.9) (0.5) (0.1)
13 (2.3)
11 (2)
2 (0.3)
12 (2.2)
0
12 (2.2)
183 (34) 355 (66)
IQR = interquartile range; PCNL = percutaneous nephrolithotomy; SWL = shockwave lithotripsy; RIRS = retrograde intrarenal surgery.
procedures as well as stones passed after shockwave lithotripsy (SWL) and stones passed spontaneusly. Samples from Rabin Medical Center were washed and dried before bottling for shipment to Beck Analytical Services (Indianapolis, IN) for mineral analysis by Fourier-transform infrared spectroscopy using the KBr pellet method and a Bruker Alpha-T spectrometer. Samples from Hadassah Hebrew University Hospital were washed and stored in precleaned bottles, and X-ray diffraction analysis measurements were performed on the advance diffractometer (Bruker AXS, Karlsruhe, Germany) with a goniometer radius 2177.5 mm, Gobel mirror parallel-beam optics, 2 degree Soller slits, and 0.6-mm receiving slit. Any stone component was reported and calculated as a percentage of occurrence in the entire cohort, as well as percentage by sex and age groups. Statistical analysis Statistical analysis included descriptive analysis (range, mean, and interquartile range for continuous variable and proportions for discrete variables) and comparative tests (chi-
square for discrete variables, Mann-Whitney test for ordinal variables, and t test for continuous variables). A P value < 0.05 was considered statistically significant. Results The study cohort included 401 (74.5%) men and 137 (25.5%) women with a male to female ratio of 2.9:1 and a median age of 48 years. Most stones were retrieved during ureteroscopy (57%) followed by percutaneous nephrolithotomy (27.7%). The majority of the stones were of mixed composition (66%) (Table 1). The peak age of presentation in the entire cohort was between ages 50 and 60. A bimodal distribution was noted for female patients, however, which was not observed in male patients (Fig. 1). The occurrence frequency of stone components and homogeneity is shown in Table 2. Calcium oxalate monohydrate (COM) was the predominant stone component (74.2%), followed by calcium phosphate (36.6%). UA stones were found in only 14.5% of the patients. In the pure stones group, however, the rate of UA was higher (48/128 vs 26%). Infection stones, including magnesium ammonium phosphate and carbonite-apatite, rarely occurred in a pure form. In contrast, cystine stones occurred only in the pure form (Table 2). Significant sex differences in stone composition were found. While COM was the predominant component in both sexes, it Table 3. Occurrence Frequency of Stone Components According to Sex Stone components
FIG. 1.
Age distribution by sex.
Calcium oxalate monohydrate Calcium oxalate dihydrate Calcium phosphate Uric acid Carbonite-apatite Magnesium ammonium phosphate (struvite) Calcium hydrogen phosphate dihydrate (brushite) Cystine
Male (%)
Female (%)
P value
77.3 38.2 37.4 14.5 8.2 2.0
65.0 21.9 34.3 14.6 24.8 10.9
0.004
Urinary Stone Composition in Israel: Current Status and Variation with Age and Sex—A Bicenter Study Kalba D. Usman, MD,1,* Shay Golan, MD,1,* Tamer Abdin, MD,2 Pinhas M. Livne, MD,1 Dov Pode, MD,2 Mordechai Duvdevani, MD,2 and David Lifshitz, MD1
Abstract
Background and Purpose: The epidemiologic data regarding stone composition in Israel are based on anachronistic methods of stone analysis. Historically, Israel was noted for an unusually high percentage of uric acid stones. The aim of the study was to describe the current stone composition distribution in Israel, using modern techniques of urinary stone analysis. Age and sex correlations were investigated. Materials and Methods: In a bicenter study, using infrared spectroscopy and X-ray diffraction, stones from five hundred and thirty eight (538) patients were analyzed and demographic data recorded. Results: The study cohort included 401 men (74.5%) and 137 women (25.5%) with a male to female ratio of 2.9:1 and a median age of 48 years (range 2–85 years). While calcium oxalate monohydrate was the predominant component in both sexes, it was lower in female patients (77.3% vs 65%). The rate of infection stones (struvite + carbonate apatite) was significantly higher in women (35.7% vs 10.2%). Uric acid stones were found in only 14.5% of the patients and increased with age. Conversely, the rate of calcium oxalate dihydrate decreased with age. Conclusions: Modern techniques of urinary stone analysis showed that the most frequent stone component in Israel is calcium oxalate monohydrate. In contrast to earlier reports and in accordance with reports from other countries, the overall frequency of uric acid is 14.5%. With age, the frequency of uric acid increases reaching 21% in persons > 60 years old. A significant sex difference was noted in the distribution of calcium oxalate stones and infection stones. The classic 3:1 ratio was maintained, however. Introduction
U
rolithiasis is a common disease throughout the world. Regional differences attributed to factors such as climate and diet are noticeable, however. Although higher prevalence of stone disease is found in hot or dry climates. it seems that genetic and dietary factors may offset the climate effect. For example, the reported prevalence of stone disease in Asia, between 1% and 5%,1 is lower than the recently reported prevalence in the United States of about 9%.2 Dietary changes may also be responsible for the steady increase of stone disease during the last 5 decades as well as for the decrease in the male to female ratio.3 Furthermore, changes in stone composition are noted with a higher prevalence of uric acid (UA) stones associated with increasing body mass index.4 Israel geographically belongs to the Mediterranean stone belt,5 while demographically, its population comprises various ethnic groups that have immigrated from different regions of the world. Many persons as well as substantial
groups underwent a change of profession, social status, and climatic environment. The above conditions made Israel an interesting country as far as the study of epidemiology of urolithiasis is concern. Earlier studies from Israel, often quoted in urology textbooks, noted an unusually high prevalence of UA stones reaching up to 40%.6 These studies, however, were based mostly on chemical stone analysis. The purpose of our study was to examine the current stone composition in Israel using modern stone analysis techniques. Data from two tertiary centers located in different geographical regions (Tel Aviv area and Jerusalem) were obtained to overcome regional differences. In addition to the overall frequency of different stone components, we investigated the sex and age distributions. Patients and Methods Over a 1-year period, stones from 538 patients were analyzed. The stone samples were retrieved during endoscopic
1
Rabin Medical Center, Petach Tikva and Sakler Tel Aviv University Sackler School of Medicine, Petah Tikva, Israel. Hadassah Hebrew University Hospital, Jerusalem, Israel. *Authors have equal study contribution. 2
1539
1540
USMAN ET AL.
Table 1. Distribution of Patients, Procedures, and Stone General Characteristics
Table 2. Occurrence Frequency of Stone Components and Homogeneity
Characteristic Stone component Age Mean (range) Median (IQR) Sex, n (%) Female Male Procedure, n (%) Ureteroscopy PCNL SWL RIRS Cystolithotripsy Spontaneous evacuation Stone homogeneity, n (%) Pure stones Mixed stones
48 (2–85) 50 (38, 58) 137 (25.5) 401 (74.5) 279 149 54 28 9 18
(51.8) (27.7) (10) (5.2) (1.7) (3.3)
Calcium oxalate monohydrate Calcium oxalate dihydrate Calcium phosphate Uric acid Carbonite-apatite Magnesium ammonium phosphate (struvite) Calcium hydrogen phosphate dihydrate (brushite) Cystine
Total number (%)
Mixed (%)
Pure (%)
399 (74.2)
309 (57.4)
90 (16.7)
183 (34)
165 (30.6)
18 (3.3)
197 78 67 23
188 30 64 22
9 48 3 1
(36.6) (14.5) (12) (4.1)
(34.9) (5.5) (11.9) (4)
(1.6) (8.9) (0.5) (0.1)
13 (2.3)
11 (2)
2 (0.3)
12 (2.2)
0
12 (2.2)
183 (34) 355 (66)
IQR = interquartile range; PCNL = percutaneous nephrolithotomy; SWL = shockwave lithotripsy; RIRS = retrograde intrarenal surgery.
procedures as well as stones passed after shockwave lithotripsy (SWL) and stones passed spontaneusly. Samples from Rabin Medical Center were washed and dried before bottling for shipment to Beck Analytical Services (Indianapolis, IN) for mineral analysis by Fourier-transform infrared spectroscopy using the KBr pellet method and a Bruker Alpha-T spectrometer. Samples from Hadassah Hebrew University Hospital were washed and stored in precleaned bottles, and X-ray diffraction analysis measurements were performed on the advance diffractometer (Bruker AXS, Karlsruhe, Germany) with a goniometer radius 2177.5 mm, Gobel mirror parallel-beam optics, 2 degree Soller slits, and 0.6-mm receiving slit. Any stone component was reported and calculated as a percentage of occurrence in the entire cohort, as well as percentage by sex and age groups. Statistical analysis Statistical analysis included descriptive analysis (range, mean, and interquartile range for continuous variable and proportions for discrete variables) and comparative tests (chi-
square for discrete variables, Mann-Whitney test for ordinal variables, and t test for continuous variables). A P value < 0.05 was considered statistically significant. Results The study cohort included 401 (74.5%) men and 137 (25.5%) women with a male to female ratio of 2.9:1 and a median age of 48 years. Most stones were retrieved during ureteroscopy (57%) followed by percutaneous nephrolithotomy (27.7%). The majority of the stones were of mixed composition (66%) (Table 1). The peak age of presentation in the entire cohort was between ages 50 and 60. A bimodal distribution was noted for female patients, however, which was not observed in male patients (Fig. 1). The occurrence frequency of stone components and homogeneity is shown in Table 2. Calcium oxalate monohydrate (COM) was the predominant stone component (74.2%), followed by calcium phosphate (36.6%). UA stones were found in only 14.5% of the patients. In the pure stones group, however, the rate of UA was higher (48/128 vs 26%). Infection stones, including magnesium ammonium phosphate and carbonite-apatite, rarely occurred in a pure form. In contrast, cystine stones occurred only in the pure form (Table 2). Significant sex differences in stone composition were found. While COM was the predominant component in both sexes, it Table 3. Occurrence Frequency of Stone Components According to Sex Stone components
FIG. 1.
Age distribution by sex.
Calcium oxalate monohydrate Calcium oxalate dihydrate Calcium phosphate Uric acid Carbonite-apatite Magnesium ammonium phosphate (struvite) Calcium hydrogen phosphate dihydrate (brushite) Cystine
Male (%)
Female (%)
P value
77.3 38.2 37.4 14.5 8.2 2.0
65.0 21.9 34.3 14.6 24.8 10.9
0.004
