The role of affluence and diet in the genesis of calcium-containing stones. In: Vahlensieck W, Gasser G, editors. Pathogenese und Klinik der Harnsteine VI. Heidelberg: Steinkopff; 1978. pp. 5-14. [DOI: 10.1007/978-3-642-47063-9_2]

Are upper urinary tract stones more common in more deprived populations?

Purpose:

To examine the relationship between deprivation and upper tract calculus formation, and provide a contemporary estimate of the incidence of upper urinary tract stone disease.

Methods:

A retrospective review of hospital episodes for patients presenting to our institution with upper urinary tract stone disease in a 3-year period between 2010 and 2014. Incidence of stone disease was calculated and stratified according to deprivation, as measured by the index of multiple deprivation (IMD) and its subdomains. Poisson regression was used to model the relationship between deprivation and stone disease.

Results:

The overall incidence of upper urinary tract stone disease was 115 patients/100,000 person-years (95% confidence interval (CI) 108–122 per 100,000 person-years). There is a link between the IMD (as well as a number of its subdomains) and stone disease. The rate of incident stone disease was 50.6% higher in the most deprived quintile of the IMD when compared to the least deprived ( p < 0.001). Multivariate Poisson regression found that education, skills and training deprivation was the subdomain that predicted stone disease most strongly, with the incidence rate ratio being 1.15 (95% CI 1.053–1.261) for each increase in quintile.

Conclusion:

This study provides a contemporary measure of the incidence of upper urinary tract stone disease derived from a population in the Midlands of England. It informs our understanding of the link between types of deprivation and stone occurrence.

Level of evidence:

2b

[Composition of 359 kidney stones from the East region of Algeria]

PURPOSE

Determine stones composition of the upper urinary tract in the eastern region of Algeria.

METHODS

Our study focuses on a set of 359 stones of the upper urinary tract collected between January 2007 and December 2012 at hospitals in the eastern region of Algeria and analyzed by Fourier transform infrared spectroscopy.

RESULTS

The male/female ratio was only 1.32. Calcium oxalate prevailed in 68.5% of stones and 49.3% of nuclei, mainly as whewellite (51.8% of stones and 37.9% of nuclei vs 16.7% and 11.4% respectively for weddellite). Carbapatite prevailed in 15% of stones and 29.8% of nuclei. The struvite, identified in 11.1% of calculi, prevailed in 3.9% of stones and 3.1% of nuclei. Among purines, uric acid prevailed with frequencies quite close to 8.9% and 7% respectively in the stone and in the nucleus while the ammonium urate prevailed in only 0.3% of stones and 3.3% of nuclei. The cystine frequency was 3.6% in both stone and nucleus. The frequency of stone with umbilication was 26.2%. Whewellite was the main component of umbilicated stones with Randall's plaque.

CONCLUSION

Our results suggest that stones of the urinary tract in the Algerian east region resemble those observed in industrialized countries. Some features such as stones location, the whewellite prevalence, the frequencies of main components in both the stone and the nucleus as well as the formation of stones on renal papilla confirm this trend.

LEVEL OF EVIDENCE

4.

Thirty-eight years of stone meetings in Europe

Of decisive importance for the many research groups all over Europe were the scientific symposia dealing with the theoretical foundations and clinical aspects of urinary stone disease. There were several sources from which today's European Urinary Stone meetings and the "Eurolithiasis Society" itself arose. It was a long way from Leeds in 1968 to Jena 1970, Bonn-Vienna in 1972 and to 11 European meetings from 1989 to 2005. Which developments in urinary stone disease research have been presented at our congresses during the past 40 years? The 1970s and 1980s are the years marked by efforts to measure the important lithogenic substances such as calcium, ionized calcium, uric acid, phosphate, oxalate with reliable methods. Hypercalciuria and specifically mild hyperoxaluria were the topics of numerous investigations in the 1970s, 1980s and 1990s. The calcium-loading test described by Pak has been discussed frequently since its application. It became apparent that oxalic acid is more important in urinary stone formation than hypercalciuria. Of importance were investigations done by Robertson and his colleagues on the influence of diet (in particular, an animal protein-rich diet) on urinary stone formation. Another emphasis of research was investigation of the crystallization process: supersaturation, crystal growth and aggregation are important steps in urinary stone formation. Of great importance in the formation of urinary stones are inhibitors (inhibitory activity): citrate, magnesium, pyrophosphate, macromolecules: GAGs, THP etc. and it became possible in the early 1970s to determine substances such as Tamm-Horsfall protein (THP) and GAGs. Much attention in the 1970s and 1980s was focused on urinary stone analysis (X-ray diffraction, infrared spectroscopy, polarization microscopy) and standardization of these methods. In the mid-1980s, a whole series of epidemiological studies were carried out, with data for the Federal Republic of Germany, East Germany, Czechoslovakia and Austria. The search for "stone-removing" medications, their description and clinical use was the subject of much clinical research and in vitro examinations. A definite advance occurred in the 1980s with the development of new instrumental technologies for the management of urinary stones such as shockwave ("Stosswelle") lithotripsy, percutaneous nephrolithotomy and ureterorenoscopy (" breakthrough innovations"). Since the 8th European Urolithiasis Symposium there have regularly been presentations pertaining to the topic of the molecular basis of inherited lithiasis. The last 10-15 years have shown an increasing turning toward the importance of cellular alterations and supersaturation and their relation to stone formation. In conclusion, I would like to note that it is of decisive importance for the research groups all over Europe to organize scientific symposia dealing with the theoretical foundations and clinical aspects of urinary stone disease under the protection of the European Urolithiasis Society.

Épidémiologie actuelle de la lithiase rénale en France

Nephrolithiasis is a frequent disease that affects about 10% of people in western countries. The prevalence of calcium oxalate stones has been constantly increasing during the past fifty years in France as well as in other industrialized countries. Stone composition varies depending to gender and age of patients and also underlines the role of other risk factors and associated pathologies such as body mass index and diabetes mellitus. The decrease in struvite frequency in female patients is the result of a significantly improved diagnostic and treatment of urinary tract infections by urea-splitting bacteria. In contrast, the increasing occurrence of weddellite calculi in stone forming women aged more than 50 years could be the consequence of post-menopausal therapy. A high prevalence of uric acid was found in overweight and obese stone formers and in diabetic ones as well. Another important finding was the increased occurrence with time of calcium oxalate stones formed from papillary Randall's plaques, especially in young patients. Nutritional risk factors for stone disease are well known: they include excessive consumption of animal proteins, sodium chloride and rapidly absorbed glucides, and insufficient dietary intake of fruits and potassium-rich vegetables, which provide an alkaline load. As a consequence, an excessive production of hydrogen ions may induce several urinary disorders including low urine pH, high urine calcium and uric acid excretion and low urine citrate excretion. Excess in calorie intake, high chocolate consumption inducing hyperoxaluria and low water intake are other factors, which favour excessive urine concentration of solutes. Restoring the dietary balance is the first advice to prevent stone recurrence. However, the striking increase of some types of calculi, such as calcium oxalate stones developed from Randall's plaque, should alert to peculiar lithogenetic risk factors and suggests that specific advices should be given to prevent stone formation.

Idiopathic calcium oxalate urolithiasis: risk factors and conservative treatment

Idiopathic calcium oxalate urolithiasis is a frequent and recurrent multifactorial disease. This review focuses on urinary and dietary risk factors for this disease and conservative strategies for rectifying them. Dietary oxalate and calcium and their respective urinary excretions have been extensively investigated during the last 10 years. Urinary oxalate has emerged as the most important determinant of calcium oxalate crystallization while the role of urinary calcium has shifted to bone balance and osteoporosis. Dietary calcium restriction increases urinary oxalate and contributes to a negative bone balance. It has therefore been abandoned as a means to reduce the risk of calcium oxalate kidney stone formation. Calcium oxalate kidney stone patients are advised to increase their fluid intake to achieve a urine volume of 2 l or more; the recommended calcium intake is 800-1200 mg/day; high oxalate foods should be restricted; daily protein intake should be between 0.8 and 1 g/kg body weight/day; essential fats should be included; vegetable and fruit (except oxalate-rich vegetables) intake should be increased. The use of calcium supplements has potential benefits but needs to be examined further.

Sensitivity to meat protein intake and hyperoxaluria in idiopathic calcium stone formers

BACKGROUND

High protein intake is an accepted risk factor for renal stone disease. Whether meat protein intake affects oxaluria, however, remains controversial in healthy subjects and in stone formers. This study was designed (1) to test the oxaluric response to a meat protein load in male recurrent idiopathic calcium stone formers (ICSFs) with and without mild metabolic hyperoxaluria (MMH and non-MMH, respectively), as well as in healthy controls, and (2) to seek for possible disturbed vitamin B(6) metabolism in MMH, in analogy with primary hyperoxaluria.

METHODS

Twelve MMH, 8 non-MMH, and 13 healthy males were studied after five days on a high meat protein diet (HPD; 700 g meat/fish daily) following a run-in phase of five days on a moderate protein diet (MPD; 160 g meat/fish daily). In both diets, oxalate-rich nutrients were avoided, as well as sweeteners and vitamin C-containing medicines. Twenty-four-hour urinary excretion of oxalate was measured on the last day of each period, along with 4-pyridoxic acid (U(4PA)) and markers of protein intake, that is, urea, phosphate, uric acid, and sulfate. Serum pyridoxal 5' phosphate (S(P5P)) was measured after protein loading.

RESULTS

Switching from MPD (0.97 +/- 0.18 g protein/kg/day) to HPD (2.26 +/- 0.38 g protein/kg/day) led to the expected rise in the urinary excretion rates of all markers of protein intake in all subjects. Concurrently, the mean urinary excretion of oxalate increased in ICSFs taken as a whole (+73 +/- 134 micromol/24 h, P = 0.024) as well as in the MMH subgroup (+100 +/- 144 micromol/24 h, P = 0.034) but not in controls (-17 +/- 63 micromol/24 h). In seven ICSFs (4 MMH and 3 non-MMH) but in none of the healthy controls (P = 0.016, chi square), an increment in oxaluria was observed and considered as significant based on the intra-assay coefficient of variation at our laboratory (8.5%). There was no difference in S(P5P)nd U(4PA)etween the groups after protein loading.

CONCLUSION

Approximately one third of ICSFs with or without so-called MMH are sensitive to meat protein in terms of oxalate excretion, as opposed to healthy subjects. Mechanisms underlying this sensitivity to meat protein remain to be elucidated and do not seem to involve vitamin B(6) deficiency.

[The effect of different food forms on the urine composition and the risk of calcium oxalate stone formation]

The aim of this 17-day study was to examine the influence of four different diets on urine composition and the risk of calcium oxalate stone formation in 10 healthy male subjects. In the course of phase 0, the subjects were on their individual diet for 2 days. In the following phases I, II, and III the subjects received three different standard diets for a duration of 5 days each. Whereas DIET 1 (normal mixed diet) corresponded to the dietary habits of men aged 19 to 35 years, DIET 2 (balanced mixed diet) and DIET 3 (ovo-lacto-vegetarian diet) were calculated according to the dietary recommendations of the German Society of Nutrition (DGE) for the same age-group. The risk of calcium oxalate stone formation, calculated by the computer program EQUIL of FINLAYSON, was highest on the self-selected diet and on DIET 1, but declined significantly on the intake of DIET 2 by 50% on average compared to DIET 1 and by 61% compared to phase 0. On DIET 3 no further significant decline in the risk of calcium oxalate stone formation was observed. Therefore, it can be concluded that the change of usual dietary habits into a balanced mixed diet significantly reduces the risk of calcium oxalate stone formation. With a vegetarian diet a comparable decline in urine supersaturation of calcium oxalate can be achieved with respect to a mixed diet according to requirements. Since urinary oxalic acid excretion increased significantly, a vegetarian diet is not recommend for calcium oxalate stone patients with absorptive hyperoxaluria.

Environmental factors in the pathophysiology of recurrent idiopathic calcium urolithiasis (RCU), with emphasis on nutrition

A number of environmental factors are under discussion as possibly implicated in the etiology of RCU. On the basis of data in the literature and our own results, we attempted a critical weighting up of the possible contributions of climate, pollution, stress, nutrition in general and especially oxalate and minerals in the nutrition. It was concluded that there is a need for more in-depth research into the response of the body to challenges from the environment, in particular nutrition.

Dietary intake and habits of Japanese renal stone patients

The daily consumption of various nutrients as well as the daily habits of 241 male stone patients were investigated. Hypercalciuric (300 mg. or more per day) calcium stone patients ingested much more total protein, fats, oils and calcium than normocalciuric calcium stone patients, and uric acid stone patients ingested much more total and animal protein, and carbohydrates than calcium stone patients. However, the amount of ingested calcium by the patients (470 mg.) was similar to that of age-matched healthy male subjects (476 mg.) and did not reach the level of the daily nutritive requirements (600 mg.). The patients ingested large amounts of nutrients, especially animal protein, during the evening meal. From these results it was believed that synthetic dietary management, including not only ingesting various amounts of nutrients but also changing dietary habits, is necessary for the prophylaxis of renal stones.

Trends in urolithiasis in various ethnic groups and by age, in Israel

A survey of upper urinary tract stone composition was carried out over 8 years (1974-1982) in 1147 patients, following a previous survey (1966-1974). Trends in the development of stone formation were found. The most obvious differences were fewer pure calcium oxalate (0.75 versus 5.50%) and uric acid stones (6.11 versus 13.30%) and more mixed stones than in our previous study. In most ethnic groups urinary stones were composed of calcium oxalate/calcium phosphate. A higher prevalence of stones in Israeli-born Jews was noted, in comparison with our previous survey. Age group analysis showed this increase to be limited to the 21-50-year-old group, in contradistinction to a clear decrease in stone formation in Israeli-born Arabs and Jews under the age of 20 years.

Stress as a principal cause of calcium oxalate urolithiasis

Epidemiological information on calcium oxalate urolithiasis is reviewed and interpreted according to a proposed stress-related mechanism. This mechanism involves hypothalamo-hypophyseal secretion firstly of vasopressin which acts directly to produce hypertonic urine and secondly of adrenocorticotropin which acts via a secondary hyperparathyroid mechanism to raise serum calcium levels.

A case-control study of dietary intake of renal stone patients. I. Preliminary analysis

The average daily dietary intake of 88 idiopathic renal stone cases and 88 age and sex matched controls was assessed by history using a standardised questionnaire. Statistical analysis was undertaken on the whole group and on male and female subgroups, to establish if there were any significant differences between cases and controls. There were statistically significant differences in dietary intake between the whole group, the female cases and the control group. Male cases showed only a significantly lower intake of thiamine compared to controls. There was little difference between cases and controls intake of iron or multivitamin supplements but vitamin C supplements (greater than 1 g/day) were taken more than twice as frequently by cases than controls. These results suggest that control dietary studies of renal stone patients without regard to their sex may conceal many differences in dietary intake between cases and controls.

A non-steroidal anti-inflammatory drug (flurbiprofen) to control idiopathic hypercalciuria resistant to dietary manipulation

Twenty-three calcium stone formers with idiopathic hypercalciuria were entered into an open study to examine the effects of flurbiprofen (Froben) on urinary calcium excretion. Five patients were withdrawn because of side effects. A statistically significant reduction in urinary calcium excretion was noted after 2 (P = 0.004) and 6 (P = 0.001) weeks' treatment. There was a significant increase in urinary calcium excretion after stopping the treatment (P = 0.0006). The results suggest that flurbiprofen reduces calcium excretion in the urine but the high incidence of side effects may limit its use in routine treatment of hypercalciuria.

The value of the 24-hour urine analysis in the assessment of stone-formers attending a general hospital outpatient clinic

The daily urinary excretion of calcium, oxalate, uric acid and glycosaminoglycans, and 24-h urinary volume and pH, were measured in 39 normal men and 65 male patients who had formed at least one calcium oxalate stone. No significant difference could be found between the two groups of subjects with respect to any of the urinary parameters. Nonetheless, a higher proportion of stone-formers than normals had daily excretion levels of oxalate in excess of the normal 95th percentile. On the other hand, there was no difference between the proportion of stone-formers and normals who fell into this category with respect to calcium excretion. It was concluded that a single 24-h urine analysis is of limited practical value in explaining the occurrence of stones or in predicting the likelihood of further episodes in unselected stone-formers attending a general hospital outpatient clinic.

The effects of vegetable and animal protein diets on calcium, urate and oxalate excretion

A group of 30 meat eating normal subjects were compared with a second group of vegetarians matched for age and sex. Their diets and urinary excretion patterns were compared by statistical analysis. A link between protein intake, particularly animal protein, and urinary calcium excretion was demonstrated and also that dietary calcium was inversely related to urinary oxalate excretion. Urinary oxalate increases with the vegetable protein content of the diet, but within the limits of these diets, animal protein does not affect oxalate excretion though it does affect excretion of urinary urate.

A control study of dietary factors in renal stone formation

Fifty-one first admission renal stone patients and an equal number of controls were interviewed and a dietary history of the average weekly intake was collected from each participant. A comparison of the dietary intake per kilogram body weight in each group was made using standard statistical procedures. None of the nutrient intakes showed a significant difference, but dietary fibre intake and the percentage of energy provided by carbohydrate were consistently higher in the control group, whereas the percentage of energy provided by fat was consistently higher in the renal stone group.

Prevalence and incidence of renal stone disease in a German population sample

261 male and 242 female patients (age 15-65 years) were questioned about renal colics with passage of renal stones. The patients were questioned while undergoing a medical examination. The prevalence of renal stones varied between 1.1% (males 15-29 years) and 20.6% (males 50-65 years) with an average of 6.9%. The incidence of passage of a calculus was 0.62% percent of the population per year. These figures in a German population sample are in agreement with more recent data from other industrialized countries and point to the magnitude of renal stone disease as a public health problem.

Urinary sodium excretion in renal stone formers. An epidemiological study

In the present investigation 238 randomly selected male individuals of the general population (age 19--41 years) and 42 age-matched male patients with recurrent renal stone formation (calcium oxalate and/or calcium phosphate) were studied under outpatient conditions without dietary restrictions. Urinary Na excretion was 207 +/- 82 mmol/24 h (range 55--570) in controls and 208 +/- 100 (range 76--575) in recurrent renal stone formers. Both in controls (r = 0.36; p less than 0.01) and in stone formers (r = 0.4; p less than 0.01) a significant correlation was observed between urinary excretion of sodium and calcium. Urinary sodium excretion was unrelated to systolic or diastolic blood pressure in normotensive or hypertensive individuals. This finding indicates that factors other than sodium are involved in the maintenance of hypertension. Urinary sodium, presumably an index of intake of nutrients, was significantly correlated to several coronary risk factors, e.g. fasting glucose, cholesterol and overweight. There existed a significant inverse relationship between fasting plasma phosphate and urinary sodium, but not between fasting plasma phosphate and serum iPTH or urinary cAMP. This finding points to some function of sodium excretion as one determinant of plasma phosphate.

[Parathormone and renal excretion in healthy controls and patients with nephrolithiasis (author's transl)]

Idiopathic nephrolithiasis with recurrent ca-oxalat stones are investigated for occult renal dysfunction or for disturbed clearance of PTH. After injection of PTE a significant increase of renal excretion of Na+, K+, Ca2+ and uric acid was observed normalizing within 120 min after injection. Healthy controls showed similar changes, and following PTH the cAMP generating capacity of patients with recurrent stones was in normal range. The turn over rate of PTH was 30-40 min without differences in the collectives studied.

Should recurrent calcium oxalate stone formers become vegetarians?

The hypothesis that the incidence of calcium stone disease is related to the consumption of animal protein has been examined. Within the male population, recurrent idiopathic stone formers consumed more animal protein than did normal subjects. Single stone formers had animal protein intakes intermediate between those of normal men and those of recurrent stone formers. A high animal protein intake caused a significant increase in the urinary excretion of calcium, oxalate and uric acid, 3 of the 6 main urinary risk factors for calcium stone formation. The overall relative probability of forming stones, calculated from the combination of the 6 main urinary risk factors, was markedly increased by a high animal protein diet. Conversely, a low animal protein intake, such as taken by vegetarians, was associated with a low excretion of calcium, oxalate and uric acid and a low relative probability of forming stones.