Parathyroid gland function in subgroups of metabolically mediated urolithiasis as evaluated by serum parathyroid hormone, and urinary and nephrogenous cyclic nucleotides

Postprandial hyperinsulinaemia, insulin resistance and inappropriately high phosphaturia are features of younger males with idiopathic calcium urolithiasis: attenuation by ascorbic acid supplementation of a test meal

In idiopathic recurrent calcium urolithiasis (RCU) the state of insulin and carbohydrate metabolism, and relationships to minerals such as phosphate, are insufficiently understood. Therefore, in two groups of males with RCU (n = 30) and healthy controls (n = 8) the response to an oral carbohydrate- and calcium-rich test meal was studied with respect to glucose, insulin, and C-peptide in peripheral venous blood (taken before and up to 180 min post-load), and phosphate and glucose in fasting and post-load urine. In one RCU group (n = 16) the meal was supplemented with ascorbic acid (ASC; 5 mg/kg body weight). The mean age (RCU 29, RCU + ASC 30, controls 27 years) and mean body mass index [RCU 24.4, RCU + ASC 25.0, controls 24.0 kg/m2] were similar. Insulin resistance (synonymous sensitivity of peripheral organs to insulin) was calculated from insulin serum concentration, as was also integrated insulin, C-peptide, and glucose. Untreated stone patients (RCU) developed hyperinsulinaemia between 60 and 120 min post-load, increased integrated insulin, and insulin resistance (P < or = 0.05 vs controls), whereas the rise of C-peptide and glycaemia (absolute and integrated values) was only of borderline significance. Fasting phosphaturia was low in both RCU subgroups vs controls; however, phosphaturia in untreated RCU rose in response to the meal, contrasting sharply with a decrease in controls. ASC supplementation of the meal (in the RCU + ASC subgroup) normalized insulin, failed to normalize post-load phosphaturia, but reduced post-load glucosuria and urinary pH significantly (mean pH values 5.55 vs 5.93 in untreated RCU, controls 5.50). Postprandial urinary oxalate, calcium, protein, and supersaturation products were not changed. The postprandial changes in phosphaturia and insulin sensitivity were inversely correlated (n = 38, r = -0.44, P = 0.007). It was concluded that in younger RCU males: (1) postprandial hyperinsulinaemia, the failure to reduce phosphaturia and - within limits - glucosuria, appropriately, as well as poor urine acidification are important features of the metabolism; (2) these phenomena are probably caused by insulin resistance of organs, the kidney included; and (3) the addition of a supraphysiological dose of ASC to a meal, the subsequent abolition of hyperinsulinaemia, and the restoration of normal urine acidification suggest that this antioxidant is capable of counteracting some pre-existing basic abnormality of cell metabolism in RCU.

Crystalluria determined by polarization microscopy. Technique and results in healthy control subjects and patients with idiopathic recurrent calcium urolithiasis classified in accordance with calciuria

A retrospective study was done on the nature and degree of crystalluria in spontaneously voided fasting and postprandial urine of patients with recurrent idiopathic calcium urolithiasis (RCU) divided into normocalciuria (20 males, 20 females) and hypercalciuria patients (20 males, 20 females), and controls (20 males, 20 females). The crystals were obtained using a filter technique and identified by microscopy. In addition, individual data, clinical chemistry variables and indices reflecting the risk of calcium phosphate and calcium oxalate crystallization were evaluated. In contrast to findings of other investigators of crystalluria we observed only a few crystals on the filters. The most frequently occurring phases were (in this order) a urate-containing phase (tentatively termed uric), an amorphous calcium phosphate phase (tentatively termed isotropic) and a phase of spheroid-like particles, not yet definitely characterized (tentatively termed spheroid). Calcium oxalate crystals were found only exceptionally. There was no relationship between the degree of calciuria (normo- versus hypercalciuric RCU) and crystalluria. Among RCU, males generally had a predominance of the isotropic, females of the spheroid phase, as compared with controls. Also, RCU females were generally obese, and their spheroid score and lean body mass correlated negatively and significantly. The calcium phosphate and calcium oxalate risk indices were always low in normal individuals, higher in RCU. Patients of both sexes with urinary stones had normal parathyroid gland function, but higher total calcium in fasting serum and higher urinary pH as compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)