Prevalence of upper urinary tract stone disease in a rural community of north-eastern Thailand

The first epidemiology of urolithiasis in Northern Vietnam: Urinary stone composition, age, gender, season, and clinical features study

OBJECTIVES

The aim of this study is to analyze the compositions of urinary stones and investigate their distributions in different ages, genders, seasons, and clinical features of Northern Vietnamese patients.

METHODS

A total of 231 patients with urinary stones from Northern Vietnam were collected and analyzed composition from 1/2021-12/2022. For all patients, age, sex, stone location, stone side, urine pH, and hospitalized date (month) were collected.

RESULTS

Kidney stones are more frequently found in men than women with the male: female urinary stones ratio in this study being 1.96:1. The highest stone prevalence appeared between 60 and 69 years old. The most common stone composition was calcium oxalate, followed by calcium phosphate, uric acid, struvite, and cysteine. Mix stones of CaOx and CaP were more prevalent than pure stones. Males submitted more CaOx, CaP, and UA stones, whereas females were susceptible to infectious stones. Stones were more frequently found on the left side of the upper urinary tract (51.9%) than on the right side (27.3%) and lower urinary tract (7.8%). Cultural tendency leads to a smaller number of stones during the Lunar new year (February), and Ghost month (August).

Anti-Proteus Activity, Anti-Struvite Crystal, and Phytochemical Analysis of Sida acuta Burm. F. Ethanolic Leaf Extract

Proteus mirabilis is a significant cause of urinary tract infection that may contribute to struvite stones. Anti-infection of this bacterium and anti-struvite formation must be considered. Sida acuta Burm. F. (SA) has been used for the treatment of diseases related to kidneys. Therefore, we investigated the effects of the SA leaf ethanolic extract (SAEE) on growth and on virulent factors (swarming motility and urease activity) of Proteus mirabilis isolated from kidney stone formers. We also evaluated anti-struvite crystal formation and phytochemical constituents of SAEE. The minimum inhibitory concentrations (MICs) of SAEE against three clinical P. mirabilis isolates were 8 mg/mL. Intriguingly, the 1/2MIC of SAEE had significant inhibitory effects on the swarming motility and urease activity of clinical P. mirabilis isolates when compared with the condition without SAEE. The SAEE at the various concentrations significantly inhibited the average weights of struvite crystals in a dose-dependent manner, compared with the control. The phytochemical analysis revealed that SAEE contained catechin, chlorogenic acid, rutin, and ferulic acid. This study indicated that SAEE has anti-P. mirabilis and anti-struvite crystal activities via its bioactive compounds. For this reason, SAEE may be developed as a new agent for the treatment of struvite stone induced by P. mirabilis.

Epidemiology of urolithiasis in Asia

In Asia, about 1%-19.1% of the population suffer from urolithiasis. However, due to variations in socio-economic status and geographic locations, the prevalence and incidence have changed in different countries or regions over the years. The research for risk factors of urinary tract stones is of predominant importance. In this review, we find the prevalence of urolithiasis is 5%-19.1% in West Asia, Southeast Asia, South Asia, as well as some developed countries (South Korea and Japan), whereas, it is only 1%-8% in most part of East Asia and North Asia. The recurrence rate ranges from 21% to 53% after 3-5 years. Calcium oxalate (75%-90%) is the most frequent component of calculi, followed by uric acid (5%-20%), calcium phosphate (6%-13%), struvite (2%-15%), apatite (1%) and cystine (0.5%-1%). The incidence of urolithiasis reaches its peak in population aged over 30 years. Males are more likely to suffer from urinary calculi. Because of different dietary habits or genetic background, differences of prevalence among races or nationalities also exist. Genetic mutation of specific locus may contribute to the formation of different kinds of calculi. Dietary habits (westernized dietary habits and less fluid intake), as well as climatic factors (hot temperature and many hours of exposure to sunshine) play a crucial role in the development of stones. Other diseases, especially metabolic syndrome, may also contribute to urinary tract stones.

Differential colony size, cell length, and cellular proteome of Escherichia coli isolated from urine vs. stone nidus of kidney stone patients

BACKGROUND

Escherichia coli is associated with kidney stone disease, as a cause or an effect (secondary or recurrent urinary tract infection, UTI). Defining phenotypic or functional differences between E. coli inside stone nidus (ECS, associated with infection-induced stone) and outside the stone (i.e. from urine) (ECU, represented secondary infection) would be helpful to better understand bacterial involvement in this disease.

METHODS

ECS and ECU were isolated from 100 stone formers and subjected to antimicrobial susceptibility test, ERIC-PCR genotyping, determination of biofilm formation, bacterial colony size on agar plate and cell length in broth, 2-DE, nanoLC-MS/MS, protein network analysis, and pyruvate dehydrogenase (PDH) activity assay.

RESULTS

From 100 stone formers, 36 had positive bacterial culture, of which 5 pairs had identical antimicrobial susceptibility patterns and comparable ERIC-PCR genotypes. ECS had smaller colony size and longer cell length than ECU. 2-DE proteomic analysis revealed significantly differential levels of proteins involved in carbohydrate metabolism, stress response, and RNA/protein metabolism. Functional validation demonstrated lower PDH activity in ECS.

CONCLUSIONS

All these differential phenotypic and cellular proteome findings might be adaptive response of E. coli from remote infection to survive within the stone matrix that subsequently caused recurrent UTI in kidney stone patients.

Extensive characterizations of bacteria isolated from catheterized urine and stone matrices in patients with nephrolithiasis

BACKGROUND

Urinary tract infections are generally known to be associated with nephrolithiasis, particularly struvite stone, in which the most common microbe found is urea-splitting bacterium, i.e. Proteus mirabilis. However, our observation indicated that it might not be the case of stone formers in Thailand. We therefore extensively characterized microorganisms associated with all types of kidney stones.

METHODS

A total of 100 kidney stone formers (59 males and 41 females) admitted for elective percutaneous nephrolithotomy were recruited and microorganisms isolated from catheterized urine and cortex and nidus of their stones were analyzed.

RESULTS

From 100 stone formers recruited, 36 cases had a total of 45 bacterial isolates cultivated from their catheterized urine and/or stone matrices. Among these 36 cases, chemical analysis by Fourier-transformed infrared spectroscopy revealed that 8 had the previously classified 'infection-induced stones', whereas the other 28 cases had the previously classified 'metabolic stones'. Calcium oxalate (in either pure or mixed form) was the most common and found in 64 and 75% of the stone formers with and without bacterial isolates, respectively. Escherichia coli was the most common bacterium (approximately one-third of all bacterial isolates) found in urine and stone matrices (both nidus and periphery). Linear regression analysis showed significant correlation (r = 0.860, P < 0.001) between bacterial types in urine and stone matrices. Multidrug resistance was frequently found in these isolated bacteria. Moreover, urea test revealed that only 31% were urea-splitting bacteria, whereas the majority (69%) had negative urea test.

CONCLUSIONS

Our data indicate that microorganisms are associated with almost all chemical types of kidney stones and urea-splitting bacteria are not the major causative microorganisms found in urine and stone matrices of the stone formers in Thailand. These data may lead to rethinking and a new roadmap for future research regarding the role of microorganisms in kidney stone formation.

Association between occupational heat stress and kidney disease among 37,816 workers in the Thai Cohort Study (TCS)

Background

We examined the relationship between self-reported occupational heat stress and incidence of self-reported doctor-diagnosed kidney disease in Thai workers.

Methods

Data were derived from baseline (2005) and follow-up (2009) self-report questionnaires from a large national Thai Cohort Study (TCS). Analysis was restricted to full-time workers (n = 17 402 men and 20 414 women) without known kidney disease at baseline. We used logistic regression models to examine the association of incident kidney disease with heat stress at work, after adjustment for smoking, alcohol drinking, body mass index, and a large number of socioeconomic and demographic characteristics.

Results

Exposure to heat stress was more common in men than in women (22% vs 15%). A significant association between heat stress and incident kidney disease was observed in men (adjusted odds ratio [OR] = 1.48, 95% CI: 1.01–2.16). The risk of kidney disease was higher among workers reporting workplace heat stress in both 2005 and 2009. Among men exposed to prolonged heat stress, the odds of developing kidney disease was 2.22 times that of men without such exposure (95% CI 1.48–3.35, P-trend <0.001). The incidence of kidney disease was even higher among men aged 35 years or older in a physical job: 2.2% exposed to prolonged heat stress developed kidney disease compared with 0.4% with no heat exposure (adjusted OR = 5.30, 95% CI 1.17–24.13).

Conclusions

There is an association between self-reported occupational heat stress and self-reported doctor-diagnosed kidney disease in Thailand. The results indicate a need for occupational health interventions for heat stress among workers in tropical climates.

Ultrasonography assessment of hepatobiliary abnormalities in 3359 subjects with Opisthorchis viverrini infection in endemic areas of Thailand

A cross sectional study on hepatobiliary abnormalities in opisthorchiasis was performed in 8936 males and females aged from 20 to 60 years from 90 villages of Khon Kaen province, Northeast Thailand. All were stool-examined for Opisthorchis viverrini infection by standard quantitative formalin/ethyl acetate concentration technique. Of these, 3359 participants with stool egg positive underwent ultrasonography of the upper abdomen. The hepatobiliary abnormalities detected by ultrasound are described here. This study found a significantly higher frequency of advanced periductal fibrosis in persons with chronic opisthorchiasis (23.6%), particularly in males. Risks of the fibrosis included intensity of infection, and age younger than 30 years. Height of left lobe of the liver, cross-section of the gallbladder dimensions post fatty meal, sludge, and, interestingly, intrahepatic duct stones were significantly associated with the advanced periductal fibrosis. Eleven suspected cholangiocarcinoma (CCA) cases were observed. This study emphasizes the current status of high O. viverrini infection rate and the existence of hepatobiliary abnormalities including suspected CCA in opisthorchiasis endemic areas of Thailand.

Orthosiphon versus placebo in nephrolithiasis with multiple chronic complaints: a randomized control trial

Nephrolithiasis in the communities of Northeast Thailand frequently presents with multiple chronic health complaints, i.e. myofascial pain, back pain, dyspepsia, arthralgia, headache, fatigue, frank paresthesia, dysuria and any of these aggravated by purine-rich food (PRF). We assessed the efficacy of Orthosiphon in treating subjects with at least two active symptoms and negative for urine white blood cells. Subjects were randomly allocated to two groups. Crude extract of Orthosiphon given in a capsule (equivalent to 1.6-1.8 g of dried leaves of Orthosiphon) two times a day to Group 1 (n = 36) and a placebo to Group 2 (n = 40) for 14 days. The medication for each subject was packed and its code kept secret until the data analysis. Both groups were asked not to consume any of 25 purine-rich foods (PRFs) during treatment. The primary measure was the reduced sum of active severity symptoms as recorded using the visual analog scale before and after therapy (i.e. on day 7 and 14). The data on 76 subjects were processed. The mean of the total scores (95% CI) of the symptoms in each group were decreased significantly (P < 0.001); 185.6 (153.3, 218.0) to 94.7 (58.2, 131.2) in the Orthosiphon group and 196.1 (164.4, 227.8) to 89.6 (62.8, 116.5) in the placebo group. When comparing between groups, no statistically significant difference was found. The mean consumption in PRFs was significantly decreased (P < 0.001) in both groups; however, Orthosiphon did not have additional benefit over placebo at 7 and 14 days of treatment during which they reduced these foods.

Evidence suggesting a genetic contribution to kidney stone in northeastern Thai population

Genetic factor may play a role in the pathogenesis of kidney stone that is found in the northeastern (NE) Thai population. Herein, we report initial evidence suggesting genetic contribution to the disease in this population. We examined 1,034 subjects including 135 patients with kidney stone, 551 family members, and 348 villagers by radiography of kidney-ureter-bladder (KUB) and other methods, and also analyzed stones removed by surgical operations. One hundred and sixteen of 551 family members (21.05%) and 23 of the 348 villagers (6.61%) were affected with kidney stone. The relative risk (lambda(R)) of the disease among family members was 3.18. Calcium stones (whewellite, dahllite, and weddellite) were observed in about 88% of stones analyzed. Our data indicate familial aggregation of kidney stone in this population supporting that genetic factor should play some role in its pathogenesis. Genetic and genomic studies will be conducted to identify the genes associated with the disease.

K+, Na+, Mg2+, Ca2+, and water contents in human skeletal muscle: correlations among these monovalent and divalent cations and their alterations in K+ -depleted subjects

None of previous studies had simultaneously analyzed the K(+), Na(+), Mg(2+), and Ca(2+) contents in human skeletal muscle. We examined extensively and simultaneously the levels of all these cations and examined water content in vastus lateralis and pectoralis major muscles in 30 northeastern Thai men who were apparently healthy but died from an accident. Specimen collection was performed within 6 h of death. We used atomic absorption or flame photometry to measure the level of muscle cation. Histopathology of muscle and kidney was also evaluated. K(+), Na(+), Mg(2+), and Ca(2+) contents in vastus lateralis were 84.74 +/- 1.50, 38.64 +/- 0.77, 7.58 +/- 0.17, and 0.94 +/- 0.06 micromol/g wet weight, respectively, whereas K(+), Na(+), and Mg(2+) contents in pectoralis major were 82.83 +/- 1.54, 37.57 +/- 0.72, and 7.30 +/- 0.17 micromol/g wet weight, respectively. The water component was comparable in vastus lateralis and pectoralis major (78.66 +/- 0.41 and 78.09 +/- 0.56 %, respectively). Based on muscle K(+) levels, we divided the subjects into 2 main groups: K(+)-depleted (KD) group (K(+) < 80 micromol/g wet weight; n = 7) and non-K(+)-depleted (NKD) group (K(+) > or = 80 micromol/g wet weight; n = 23). In the KD muscle, Na(+) and Ca(2+) levels were significantly higher, whereas the level of Mg(2+) was significantly lower. Linear regression analysis showed significant correlations of K(+) and Mg(2+) levels and between Na(+) and Ca(2+). However, K(+) and Mg(2+) had the negative correlation with Na(+) and Ca(2+). Histopathologic examination showed no change in the KD muscles, whereas 29% (2 of 7) of the KD kidneys had vacuolization in proximal renal tubular cells. Our study not only provided the descriptive data but also implied the balance or homeostasis of these monovalent and divalent cations in their muscle pools.

Effects of potassium-magnesium citrate supplementation on cytosolic ATP citrate lyase and mitochondrial aconitase activity in leukocytes: A window on renal citrate metabolism

BACKGROUND

An increase in urinary citrate excretion is associated with a decrease in activity of renal cortical cytosolic ATP citrate lyase (ACL) and mitochondrial aconitase (m-aconitase). Because potassium-magnesium citrate causes an increase in urinary citrate excretion, we decided to assess its effects on ACL and m-aconitase in the leukocytes of renal stone patients.

METHODS

Twenty male renal stone patients were supplemented with potassium-magnesium citrate twice daily (i.e. 42 mEq potassium, 21 mEq magnesium, and 63 mEq citrate per day) for a period of 1 month. Two 24-h urine and one 15-mL heparinized blood samples were collected from each patient before and after supplementation. Urine samples were analyzed for relevant biochemical compositions. Leukocytes were separated from blood samples by centrifugation and assayed for ACL and m-aconitase activity.

RESULTS

Supplementation with potassium-magnesium citrate significantly increased urinary pH (P < 0.005) and excretions of potassium (P < 0.001), magnesium (P < 0.001) and citrate (P < 0.0001). The activity of both ACL and m-aconitase were significantly decreased (P < 0.004 and P < 0.02 respectively). The decrease in ACL activity was inversely correlated with an increase in urinary excretion of both potassium (r = -0.620, P < 0.0001) and citrate (r = -0.451, P < 0.004). A similar inverse correlation was observed between m-aconitase activity and urinary excretion of citrate (r = -0.322, P < 0.043).

CONCLUSION

Changes in enzyme activity, related to citrate metabolism in leukocytes, might reflect the status of renal tubular cells.

Renal tubular cell damage and oxidative stress in renal stone patients and the effect of potassium citrate treatment

Our objective was to evaluate the oxidative stress and renal tubular cell damage in patients who have renal stones compared to normal subjects. The patients were re-evaluated after 1-months supplementation with potassium citrate. We recruited 30 patients (11 males and 19 females) diagnosed with kidney stones and scheduled for surgical stone removal the following month, and 30 healthy non-stone formers (14 males and 16 females). Two 24-h urine samples and one heparinized blood sample were collected from each subject. Plasma was separated from the erythrocytes and assayed for creatinine, potassium, sodium, calcium, magnesium, phosphate, malondialdehyde (MDA, a lipid peroxidation product) (P-MDA), protein thiol as an indicator of protein oxidation, and vitamin E. Erythrocytes were analysed for MDA (E-MDA), reduced glutathione (GSH) and cellular glutathione peroxidase (cGPx) activity. The urine was analyzed for pH, creatinine, potassium, sodium, calcium, magnesium, phosphate, oxalate, citrate, MDA (U-MDA), total protein (U-protein) and N-acetyl-beta-glucosaminidase (NAG) activity. For the stone patients, urine and blood samples were re-evaluated after supplementation with potassium citrate (60 mEq/day) for 1 month. Renal stone patients had higher plasma creatinine and lower plasma potassium, urinary pH, potassium, magnesium, phosphate and citrate than the controls. The patients had higher P-MDA, E-MDA, U-MDA, U-protein and NAG activity, but lower GSH, cGPx activity, protein thiol and vitamin E, when compared with controls. After potassium citrate supplementation, P-MDA and E-MDA decreased while plasma vitamin E, urinary NAG activity and citrate increased. Renal stone disease is associated with high oxidative stress and damage to renal tubular cells. These abnormalities are coincident with an increase in blood lipid peroxidation products and a decrease in antioxidant status. Although supplementation with potassium citrate improved urinary citrate levels and oxidative stress, it neither reduced urinary lipid peroxidation products nor remedied the damage to renal tubular cells, probably due to the existence of kidney stones.

In vivo 31P-MRS assessment of muscle-pH, cytolsolic-[Mg2+] and phosphorylation potential after supplementing hypokaliuric renal stone patients with potassium and magnesium salts

Renal stone patients in rural northeast Thailand have a low potassium and magnesium status and low urinary excretion of citrate. We measured the changes of urinary citrate excretion and assessed in vivo skeletal muscle metabolism for intracellular-pH, cytosolic-[Mg(2+)] and phosphorylation potential (using the phosphorus magnetic resonance spectroscopy (31)P-MRS) after oral supplementation to hypokaliuric renal stone patients with oral potassium and magnesium salts. The patients comprised four groups: Group 1 (n = 10) control, Group 2 (n = 3), Group 3 (n = 5) and Group 4 (n = 6) supplemented for a month with potassium citrate, potassium citrate plus amino acid chelated magnesium, and potassium-magnesium citrate, respectively. Though urinary citrate excretion was increased in all three supplemented groups, the increases in intracellular-pH, cytosolic-[Mg(2+)] and phosphocreatine (PCr)/beta-ATP were prominent only in Group 3. The increase in PCr/beta-ATP was also observed in Group 4.

Proton magnetic resonance spectroscopy of the kidney in renal stone disease

Previous studies of renal stone disease (RSD) in Thailand indicated abnormal urinary aggregator and inhibitor composition among farmers with excessive sweat loss. Our aim was to compare the proton MR spectra obtained from the kidneys of 32 proven cases of RSD (aged 38 to 65 yrs) with nine age-matched normal control subjects. We used the STEAM sequence with TE = 15 ms and TR = 2,000 ms. The spectra at 3.25, 3.6 and 3.9 ppm were analyzed. The results showed a correlation between the three peaks (p < 0.001), however, there was no significant difference between the RSD group and the normal control subjects. We therefore concluded that there was no overloading of these osmolytes among the renal stone patients.

Urinary citrate excretion in patients with renal stone: roles of leucocyte ATP citrate lyase activity and potassium salts therapy

BACKGROUND

Hypocitraturia is a major metabolic abnormality in rural Northeast Thais with renal stones. These people also have low serum and urinary potassium and consume a high carbohydrate and low fat diet, which together might influence the intracellular metabolism and urinary excretion of citrate.

METHODS

In Study A, we measured plasma and urinary chemistries and assayed leucocyte ATP citrate lyase (ACL) activity in 30 normal urban control subjects (Group A1) and 30 rural renal stone patients (Group A2) in Northeast Thailand. Some of the subjects from both groups were also used to evaluate the intake of carbohydrate, protein and fat. In Study B, we examined the effects of potassium salts therapy with another group of 30 rural renal stone patients: Group B1 (n = 15) treated with potassium chloride and Group B2 (n = 15) with potassium-sodium citrate (with an aim to achieve 42 mEq potassium, 21 mEq sodium and 62 mEq citrate per day for 1 month).

RESULTS

In Study A, the leucocyte ACL activity of Group A1 was much lower than that of Group A2 (3.2 +/- 0.7 vs. 9.3 +/- 3.8 micromol acetylhydroxamate/mg protein/30 min, p < 0.0001). The plasma potassium, urinary excretions of potassium and citrate in Group A1 were higher than in Group A2. When data of the two groups were combined, urinary citrate excretion was inversely correlated with leucocyte ACL activity (r = 0.6783, p < 0.001). While the dietary protein intake did not differ between Groups A1 and A2, the carbohydrate intake by Group A1 was significantly lower (65.2 +/- 7.9% vs. 83.1 +/- 2.9%, p < 0.01) and fat higher (21.0 +/- 6.4% vs. 6.2 +/- 4.1%, p < 0.002) than Group A2. After treatment with potassium chloride (Group B1), only the potassium was increased (p < 0.001), while those treated with potassium-sodium citrate (Group B2) experienced a significant increase in urinary pH (p < 0.002), potassium (p < 0.001) and citrate (p < 0.001), and a decrease in leucocyte ACL activity (p < 0.001).

CONCLUSIONS

Compared to normal subjects, renal stone patients have low urinary citrate excretion with high leucocyte ACL activity. In Northeast Thailand, low potassium status and a high carbohydrate and low fat diet may cause the increased ACL activity. However, hypokaliuria, hypocitraturia and high leucocyte ACL activity can be corrected by potassium-sodium citrate salt therapy.

Incidence of urolithiasis in northeast Thailand

BACKGROUND

Urolithiasis is a major health problem in the northeast part of Thailand. In this study, we examined the prevalence of renal stone disease and differences of urinary components between stone formers and healthy control subjects in northeastern rural areas of Thailand.

METHODS

We selected 3 villages in the rural areas of Khon Kaen province in northeast Thailand. Three hundred and sixty-seven persons were asked questions relating to urolithiasis and were examined by abdominal ultrasound (US). We collected a spot urine sample from stone formers and healthy control subjects from each village.

RESULTS

Abnormal findings by US were detected in 39 individuals (10.6%), and included 31 individuals with renal calculi (8.4%), 16 with hydronephrosis (4.4%), and 1 individual with a renal cyst (0.3%). This yielded a disease rate of urinary stones in this study of 16.9%. The male/female ratio was 2/1 and the average age of the individuals examined was 40.3 +/- 13.9 years. However, there was no significant difference between the urinary parameters of stone formers and the healthy control subjects.

CONCLUSION

There was a high incidence of renal stone disease in the northeast part of Thailand, but the tendency for hypocitraturia was only found in stone formers.

Low erythrocyte Na/K-pump activity and number in northeast Thailand adults: evidence suggesting an acquired disorder

Healthy northeastern Thais have a higher erythrocyte sodium concentration and a lower erythrocyte membrane Na,K-adenosine triphosphatase (ATPase) activity than central Thais. To elucidate whether the defect is hereditary or acquired, we studied plasma sodium and potassium and erythrocyte sodium, potassium, Na,K-ATPase activity, and ouabain-binding sites (OBS) in the following groups: healthy newborns of ethnic central Thais (group 1), healthy newborns of ethnic northeast Thais (group 2), healthy adults of central Thailand ethnicity who lived in the rural central region (group 3) or in Bangkok (group 4), healthy adults of northeast Thailand ethnicity who lived in the rural northeast region (group 5) or who migrated to work in Bangkok for at least 1 year (group 6). Erythrocyte Na was higher in group 2 than in group 1. Group 3 had lower erythrocyte Na,K-ATPase activity than group 4, and it was lower in group 5 than in group 6. Among all groups, group 5 had the highest erythrocyte Na (11.6 mmol/L,F < 0.0001) and the lowest Na,K-ATPase activity (63 mmol Pi/mg x h, F < 0.0001) and erythrocyte OBS (397 sites per cell, F < 0.05) than the other adult groups. There was a positive correlation between erythrocyte Na,K-ATPase and erythrocyte OBS (r = .416, P < .0001). Multiple regression analysis demonstrated a correlation between erythrocyte Na as a dependent variable and erythrocyte OBS, plasma potassium, erythrocyte potassium, and erythrocyte Na,K-ATPase (r = .517, P < .0001). The erythrocyte Na,K-ATPase/OBS ratio, an expression of Na,K-ATPase activity equalized for the number of Na,K-pump units, was lowest among rural adults of the central region (group 3) and the northeast region (group 5) (F < 0.0002). Our data suggest that rural dwellers in Thailand tend to have lower erythrocyte Na,K-ATPase activity than urban dwellers and that this is probably acquired after birth. It was more severe among those from the northeast versus the central region, and was less severe among those who migrated to an urban area. This defect in northeast rural dwellers was probably associated with low numbers of Na,K-pump units and a defect of the pump to express activity, whereas in central rural dwellers it was probably associated with the latter condition. We postulate that there might be circulating Na,K-pump inhibitors and metabolic disturbances that cause attenuation of Na,K-ATPase function and synthesis in the northeast Thailand rural population, and that such substances may have an environmental origin. There may be a relationship between these abnormalities and sudden unexpected deaths.

Urolithiasis in Australian aboriginal children

Thirty-six Australian Aboriginal children with urolithiasis were reviewed. Males dominated the series. The age distribution ranged from 8 months to 12 years and nearly 70% were 2 years or younger. Thirty-five patients had upper tract stones. Ultrasound was diagnostic in 35 patients and was falsely negative in one. Dietary factors, dehydration and recurrent diarrhoea are incriminated in the aetiology, because ammonium urate and oxalate were the main constituents of the stones. Malformations of the urinary tract were rare and known metabolic disorders were not seen. Chemical dissolution of the stones was found to be a safe and effective adjuvant in the management of urate stones.