Differences in the free Ca²⁺ in undiluted urine from stone formers and normal subjects using a new generation of ion‐selective electrodes

Abstract

Measurement of the Ca2+ in spot urine samples at a standard pH provides a more discriminative test than total Ca for the presence of urinary tract stones. The pH dependence of the Ca2+ may have important consequences in the formation of urinary tract stones. The poor correlation between measured and computed values of Ca2+ emphasizes the importance of accurate measurement of this variable.

The influence of pH on urinary ionized [Ca+]: differences between urinary tract stone formers and normal subjects

“…In position of samples from normal subjects and stone formers. a previous paper, we showed that the concentration of the ionized fraction of calcium in urine, [Ca2+], is a better discriminant of urine between stone formers and Materials and methods normal subjects [5]. Therefore, it is possible that factors altering the [Ca2+] in urine may enhance or diminish…”

“…Urine is although the total [Ca] remains constant [5]. However, the quantitative relationship between urinary pH and generally supersaturated with respect to calcium, oxalate and phosphate [1-3] so that their variation during the [Ca2+ ], and the pH-dependence of crystalline deposition in urine is unknown.…”

“…The osmolality, phosphate, oxalate, citrate, creatinine, urate, and glycosaminoglycans were measured as described mixture was again centrifuged, 2 mL of the supernatant removed and the residue poured onto a watch-glass and previously [5]. The voided pH was measured in a urine sample drawn into a glass syringe within 45 s of micturdried in an oven; 1.0-1.5 mg of the dried sample was mixed with 5 mg of dried powdered potassium bromide.…”

“…The objectives of the present changes of temperature or pH could enhance the generation of solid phases. Hypercalciuria occurs in 50-70% study were to measure the relationship between the urinary [Ca2+ ] and pH, to determine the conditions of patients with calcium urolithiasis [4], although it is a poor discriminant between stone formers and non-stone which result in the formation of cystalline precipitates and to correlate them with any differences in the comformers, but total oxalate and phosphate levels do not consistently appear to be elevated in this group [5]. In position of samples from normal subjects and stone formers.…”

“…Several studies have Urine samples were collected from two groups of men, patients with urinary tract stone disease and ageshown that patients with urinary tract stones, or subjects who tend to form encrustations around indwelling bladmatched normal subjects. The stone formers attended St Thomas' or St Paul's Hospitals, London, and had in situ der catheters, produce a more alkaline urine [5][6][7].…”