Metabolic and physico-chemical urolithiasis parameters in the first morning urine

The 24-hour urine is golden standard for metabolic assessment of stone formers. However, due to the difficulties in collecting almost 1/3 of the samples can not be used for the analysis. Therefore, we analyzed first morning urine and calculated different risk indexes in order to asses possibility of using it in determining urolithiasis risk. Subjects were divided into 4 groups: male patients (n = 31, age 18-64), female patients (n = 31, age 25-63), male controls (n = 16, age 25-64) and female controls (n = 19, age 21-65). First morning urine pH, concentrations of calcium, magnesium, phosphate, sodium, potassium, chloride, citrate, urate, oxalate, creatinine and glycosaminoglycans were determined. Based on them, ionic concentrations and activity products of calcium oxalate and phosphate were calculated by EQUIL 2. In addition, different risk indices were calculated. The results showed that both patients and control groups had metabolic disorders, but the frequencies of occurrence were statistically independent. Significant difference in concentration of urinary constituents between corresponding patient and control groups was observed only for glycosaminoglycans in female subjects. Ca/Cit ratio and Baggio index could differentiate between both corresponding patients and control groups. The results indicate that interplay between stone formation inhibitors and promotors is responsible for urinary stone formation and that the first morning urine could be used in assessing urolithiasis risk and its prevention.

Urolithiasis and osteoporosis: clinical relevance and therapeutic implications

Several clinical and epidemiological studies revealed increased bone turnover and lower bone mass in patients with urolithiasis. Bone mass loss is particularly evident in idiopathic calcium stone formers. However, pathogenetic mechanisms and factors implicated in bone loss in these patients are still unknown. Dietary calcium restriction, increased intake of salt and animal proteins, vitamin D receptor polymorphisms are likely risk factors, while role of inflammatory cytokines, osteopontin and prostaglandin mediated bone resorption is yet to be determined. Regarding treatment and prevention, it has been proven that calcium supplements and high calcium diet with the addition of potassium alkali have an important role in prevention and treatment of both, urolithiasis and osteoporosis. Thiazide diuretics reduce hypercalciuria in renal tubules, and in addition promote osteoblast differentiation. Finally, bisphosphonates, a commonly used drugs in treatment of osteoporosis, show the potential to inhibit calcium stone formation, whereas a possible protective effect of antioxidants in bone loss and renal injurie needs to be investigated further.