Growth Studies of Calcium Oxalate in the Presence of Various Ions and Compounds

Abstract

CALCIUM oxalate is important biologically because it is a major constituent of urinary calculi. Both calcium oxalate 1 HzO (whewellite) and calcium oxalate 2 to 23 HzO (weddellite) have been identified, but analyses of collections of stones have shown that the overall amount of whewellite present generally exceeds that of weddellite. Another form of hydrated calcium oxalate, usually referred to as the trihydrate, has been found in only one calculus (Prien, 1963). We have shown (Su1 or, unpublished work) that this hydrate contains only about two water molecules and belongs to the triclinic system. It is formed when " artificial stones " of calcium oxalate are grown in the presence of certain ions, e.g. citrate or pyrophosphate ions (Lyon and Vermeulen, 1965; and this paper).In a study of the composition of urinary calculi collected from many countries and dating from the eighteenth century to the present day, we have shown that calcium oxalate can occur in any of the nucleus, interior and surface layers of the stones and that frequently it is the major constituent of all layers (Lonsdale et al., 1968~1, b). If the nucleation of calcium oxalate could be prevented, or if, when once a nucleus had already formed, the continued deposition of calcium oxalate could be stopped or controlled in such a way that the stone was easily passed, the number of cases of oxalate stones requiring hospitalisation and surgery would be considerably diminished.There is as yet no satisfactory treatment for oxalate stone formers. Control of pH is neither practical nor effective in this case since calcium oxalate is equally insoluble in both acid and alkaline solutions and only at very high pH values is its formation slowed down (see below). We are therefore investigating the types of compounds and ions which are effective in preventing or slowing down its growth. These substances can be divided into the following groups: I, cheinicals claimed to be of therapeutic use in preventing growth of oxalate calculi; 11, synthetic polyelectrolytes; 111, compounds and ions which form complexes with either the calcium or the oxalate ion; IV, miscellaneous compounds; V, dyestuffs. So far, the work applies only to in vitro systems, but its development and extension to in vivo ones is planned.

Role of Urinary Zinc and Copper on Calcium Oxalate Stone Formation

“…The formation of these crystals and the effect of various substances on their growth rate have also been studied [11][12][13]. In some studies, Zn was demonstrated to be an effective inhibitor on crystal formation in urine [12,13]. Nevertheless, the results for Zn may be deceptive because of the fact that the inhibitory effect of Zn is shown at relatively high concentrations in buffer solution or in urine.…”

“…There are many studies showing that calcium oxalate crystals, one of the most common constituents of renal calculi, are easily produced in in vitro trials. The formation of these crystals and the effect of various substances on their growth rate have also been studied [11][12][13]. In some studies, Zn was demonstrated to be an effective inhibitor on crystal formation in urine [12,13].…”

Analysis of the Trace Element Contents of Inner Nucleus and Outer Crust Parts of Urinary Calculi

“…We then supposed that the determination of lead, cadmium, nickel, and aluminum contents of inner nucleus and outer crust parts of various kinds of urinary calculi might give useful information to reach a decision on whether some trace elements, including essential and toxic ones, play a part in the disease or not. Suggestions that some trace elements tend to enhance the growth rate of deposits of crystalline calcium compounds and thus may play a part in influencing, causing, accelerating, or inhibiting the precipiation of urinary tract calculi [7][8][9] make the elucidation of these and other related subjects significant.…”

Dietary Zinc Intake and Kidney Stone Formation: Evaluation of NHANES III

“…The role of heavy metals in kidney stone formation is not well established. Some of these heavy metals may have an effect on the initial crystallization of stone components, while others affect crystal aggregation and stone growth [14,15,16]. Zinc accounts for the majority of the heavy metals in calcium-based kidney stones [5], and is present in both stone nucleus and the crust [17].…”