Analytical procedures and methods validation for oxalate content estimation

Increased urinary oxalate is considered a major risk factor in the formation of calcium oxalate kidney stones. Gut microbiota may reduce the risk of stone formation. Anyway, the first step for any research about monitoring of oxalate content (both in vitro and in vivo) is a determination of its concentration, while there are different methods reported in the literature for oxalate content determination. In this research, the main reported methods including titration with two titrators (potassium permanganate, and NaOH) as well as enzymatic method (oxalate assay kit) are presented and compared for the measurement of oxalate in both inoculated and non-inoculated media.

Effectiveness of surgical treatment of primary hyperparathyroidism with urolithiasis: correction of symptoms, laboratory parameters and stone-forming risk

Background. Parathyroidectomy is the only effective method to improve the clinical and laboratory manifestations of the primary hyperparathyroidism (PHPT) and reduce the risk of urinary calculi formation. However, there are controversies about the existence of renal form of PHPT and about the effectiveness of surgery with regard to the risk of stone formation. Aims. To evaluate the effectiveness of PHPT surgical treatment in relation to clinical, laboratory parameters, as well as the risk of stone formation. Materials and methods. In a prospective single-arm observation one-center nonrandomized study we included patients with PHPT in whom parathyroidectomy was performed in 2012–2015. We analyzed clinical and laboratory parameters before and after surgery in a period from 1 to 3 years. Results. The study included 105 patients, of whom 35 (33.3%) had urolithiasis. Blood calcium after the surgery decreased from 2.72 mmol/l [2,56; 2,97] to 2,3 mmol/l [2,2; 2,35], p < 0.001. Blood calcium concentration decreased to normal values in all patients. Parathyroid hormone level decreased from 206 pg/ml [123; 347] to 72,8 pg/ml [30; 113], p < 0.001. Clinical symptoms questionnaire estmation decreased from 4 points [3; 6] to 2 points [1; 4], p < 0.001. In patients with urolithiasis clinical symptoms before treatment were more pronounced – 5 points [3; 7] vs. 4 points [3; 5] (p = 0.015) and decreased more significantly – by 3 points [2; 4] vs 2 points [1; 3]. The daily calcium urine excretion decreased from 11.4 mmol/day [8.9; 13.9] to 5.4 mmol/day [4.1; 6.8], p < 0.001. In 2 cases (5.7%; CI, 0.7–19.2%) we observed the progression of urolithiasis after surgery. The age of patients correlated with daily calcium urine excretion after surgery (r = 0.69; p = 0.028). Conclusions. Parathyroidectomy normalizes blood calcium and parathyroid hormone, improves clinical symptoms and reduces the risk of stone formation.

Prevention of idiopathic calcium stones

The main principles of idiopathic calcium oxalate stone prevention are to maintain dilute urine through increasing fluid intake and to reduce calcium and oxalate excretion. The influence of various urinary factors on the risk of stone formation has been quantified mathematically. Urine volume and urinary oxalate concentration are most influential on the risk of stone formation, while magnesium concentration contributes a small amount to risk. It is estimated that around 50% of stone formers will form another stone within five years. Some stone formers have frequent recurrences. Most stone formers ask how they can prevent future episodes. Advice can be generic or personalized, and treatment may include changes to diet, fluid intake, and addition of drugs to alter urine biochemistry.

Epidemiology of nephrolithiasis

Nephrolithiasis is common, costly, and painful. The prevalence of nephrolithiasis, defined as a history of stone disease, varies by age, sex, race, and geography while the incidence of nephrolithiasis, defined as the first stone event, varies by age, sex, and race. Epidemiologic studies have quantified the burden of kidney stone disease and expand our understanding of risk factors. A variety of dietary, non-dietary, and urinary risk factors contribute to the risk of stone formation and the importance of these varies by age, sex, and body mass index.Low fluid intake, high urinary oxalate or calcium or uric acid, and low urinary citrate are all associated with nephrolithiasis. These results from epidemiologic studies can be considered in the clinical setting when devising treatment plans to reduce stone recurrence.

Body size and risk of kidney stones.

A variety of factors influence the formation of calcium oxalate kidney stones, including gender, diet, and urinary excretion of calcium, oxalate, and uric acid. Several of these factors may be related to body size. Because men on average have a larger body size and a threefold higher lifetime risk of stone formation than women, body size may be an important risk factor for calcium oxalate stone formation. The association between body size (height, weight, and body mass index) and the risk of kidney stone formation was studied in two large cohorts: the Nurses' Health Study (NHS; n = 89,376 women) and the Health Professionals Follow-up Study (HPFS; n = 51,529 men). Information on body size, kidney stone formation, and other exposures of interest was obtained by mailed questionnaires. A total of 1078 incident cases of kidney stones in NHS during 14 yr of follow-up and a total of 956 cases in HPFS during 8 yr of follow-up were confirmed. In both cohorts, the prevalence of a stone disease history and the incidence of stone disease were directly associated with weight and body mass index. However, the magnitude of the associations was consistently greater among women. Specifically, the age-adjusted prevalence odds ratio for women with body mass index > or = 32 kg/m2 compared with 21 to 22.9 kg/m2 was 1.76 (95% confidence interval, 1.50 to 2.07), but 1.38 (95% confidence interval, 1.16 to 1.65) for the same comparison in men. For incident stone formation, the multivariate relative risks for the similar comparisons were 1.89 (1.51 to 2.36) for women and 1.19 (0.83 to 1.70) in men. Height was inversely associated with the prevalence of stone disease but was not associated with incident stone formation. These results suggest that body size is associated with the risk of stone formation and that the magnitude of risk varies by gender. Additional studies are necessary to determine whether a reduction in body weight decreases the risk of stone formation, particularly in women.

Family history and risk of kidney stones.

Kidney stones develop more frequently in individuals with a family history of kidney stones than in those without a family history; however, little information is available regarding whether the increased risk is attributable to genetic factors, environmental exposures, or some combination. In this report, the relation between family history and risk of kidney stone formation was studied in a cohort of 37,999 male participants in the Health Professionals Follow-up Study. Information on family history, kidney stone formation, and other exposures of interest, including dietary intake, was obtained by mailed questionnaires. A family history of kidney stones was much more common in men with a personal history of stones at baseline in 1986 than in those without a history of stones (age-adjusted prevalence odds ratio, 3.16; 95% confidence interval [CI], 2.90 to 3.45). During 8 yr of follow-up, 795 incident cases of stones were documented. After adjusting for a variety of risk factors, the relative risk of incident stone formation in men with a positive family history, compared with those without, was 2.57 (95% CI, 2.19 to 3.02). Family history did not modify the inverse association between dietary calcium intake and the risk of stone formation. These results suggest that a family history of kidney stones substantially increases the risk of stone formation. In addition, these data suggest that dietary calcium restriction may increase the risk of stone formation, even among individuals with a family history of kidney stones.