Effect of Changes in Epidemiological Factors on the Composition and Racial Distribution of Renal Calculi

Abstract

One thousand and two calculi, which occurred in both black and white patients during a 15-year period, have been analysed by the X-ray diffraction technique. Calcium oxalate calculi were the most common irrespective of race. Whewellite calculi were equally distributed in both race groups, while weddelite stones appeared to be much less common amongst blacks; the opposite applied for struvite and the rare ammonium acid urate stones. The other calculi were approximately equally distributed between the two race groups. A statistically significant rising trend in the prevalence of renal stones in blacks, accompanied by changes in the ratios of the major stone forming constituents, have been a prominent feature of this survey. However, the aforementioned remained unchanged in white patients. Contrary to previous impressions, total urates exceed phosphates in whites as a major stone forming constituent. The composition of upper urinary tract stones in blacks, during the 3-year period 1981 to 1983, was very similar to the composition previously reported for the Sudanese. The profile of renal stones in blacks over the last 3 years, however, is now becoming substantially different from that of the other previously reported surveys and may be approaching that of their white compatriots. A change in the dietary patterns in blacks is occurring which is also reflected in an increasing incidence of ischaemic heart disease and which may also be responsible for the observed changes in renal stones.

Lithogenic risk factors in the urine of black and white subjects

“…Previously, the cause and composition of urinary stones in white and black South Africans differed [ 1] but they are now remarkably similar [ 4]. Many authors attribute the low incidence of urolithiasis in the black population to dietary habits [ 1, 2].…”

“…Previously they were predominantly of struvite and occurred secondary to bilharzia or urinary tract infections, and were sometimes found in the bladder [ 1]. Upper urinary tract calcium oxalate stones are now the most common type found in the urban black population of South Africa [ 4]. Many researchers have speculated whether the difference in prevalence is a question of racial immunity, dietary differences, a disparity in fluid intake, handling of solute or the presence or absence of promoters and inhibitors of renal stone formation.…”

Metabolic risk factors in patients with renal stones in KwaZulu Natal: an inter‐racial study (Asian and Whites)

“…The review of the causes of hospital admission in Fiji Island, with a similar population distribution to our province, confirmed the higher incidence of urinary stone disease in Indians than in other population groups [3].…”

“…The recurrence rate without treatment for calcium oxalate renal stones is ª 10% at 1 year, 35% at 5 years and 50% at 10 years [2]. In the USA renal stones accounted for 0.9% of hospital discharges with a mean stay of 3 days, costing $1.83 billion in 1993 [3].…”

A Urinary Detergent and Urolithiasis

“…A comparison of protein intake and fat consumption with hospital incidence of urolithiasis, as observed in 3 areas with differing levels of economic development (Anderson, 1973), revealed a well defined relationship detailing an increasing stone incidence with an increase in the dietary constituents mentioned; this is not dissimilar to that seen in cardiovascular degenerative disease. Recent work from Bloemfontein in South Africa (Beukes et al, 1987) supports this concept in so far as the composition of renal stones in the current black population is becoming substantially different from that described in earlier surveys and it may be approaching that of their white compatriots. A change in the dietary pattern in blacks is occurring which is also reflected in the increasing incidence of ischaemic heart disease, which may also be responsible for the observed changes in renal stones.…”