Calcium‐47 Absorption in Urolithiasis

Abstract

An association between high urinary calcium and calcium urolithiasis was described by Flocks in 1939 but subsequent work has fallen short of establishing the exact relationship between these 2 phenomena. In a group of patients forming calcium-containing renal stones, Melick and Henneman (1958) found that 32% had hypercalciuria. Similar findings have been made by others. Whilst an excessive urinary calcium is present in other specific diseases, hypercalciuria as a phenomenon occurring in the absence of any of these was described by Albright et al. (1953). This syndrome of idiopathic hypercalciuria was defined as the occurrence of a high urinary calcium in association with normal serum calcium, a tendency to hypophosphataemia and renal stone formation and it has since been recognised by others.Caniggia, Gennari and Cesari (1965) suggested that the hypercalciuria was primarily absorptive in origin. Peacock, Hodgkinson and Nordin (1967) showed the importance of dietary calcium in demonstrating hypercalciuria, suggesting that the hypercalciuria in stone formers was probably due to excessive absorption of calcium. An implication of this was that idiopathic stone formers were largely drawn from that segment of the population in which absorption and therefore urinary excretion of calcium was above average. This paper is concerned with the study of a group of stone formers and recurrent stone formers in the Royal Navy in whom intestinal calcium absorption has been measured by arm counting using calcium-47 (47Ca).In the past, techniques for assessing calcium absorption have required the patient to be in hospital and on a strict metabolic regime and have also required accuracy in the timing and collection of urine, faecal and blood samples. With the availability of 47Ca, a gamma-emitting radio-nuclide with a half-life of 4.53 days, a relatively simple and accurate method of measuring calcium absorption has become available using external scintillation counting (Curtis, Fellows and Rich, 1967; Wills et al., 1970;Macleod, 1971).

The Effect of Cellulose Phosphate on Intestinal Absorption and Urinary Excretion of Calcium: Some Experience in its use in the Treatment of Calcium Stone Formation

“…The findings in a previous paper have provided further support for regimes of treatment which reduce the intestinal uptake of calcium and therefore its urinary excretion in the management of recurrent calcium urolithiasis (Blacklock and Macleod, 1974).…”

“…Previous work (Blacklock and Macleod, 1974) has shown excessive intestinal absorption of calcium in a significantly high proportion of calcium stone formers. In a group of apparently solitary stone formers 76 % absorbed calcium excessively.…”

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The findings in a previous paper have provided further support for regimes of treatment which reduce the intestinal uptake of calcium and therefore its urinary excretion in the management of recurrent calcium urolithiasis (Blacklock and Macleod, 1974).Dietary measures have already been used towards this end and Nordin (1972) considers that a diet low in calcium and low in oxalates is the simplest and most effective approach in the treatment of this condition. Sodium phytate has been shown to form a relatively insoluble complex with calcium in the gut and the effect of this has been to lower urinary calcium in patients with idiopathic hypercalciuria (Henneman et al, 1958); there is however an increase in urinary phosphate excretion at the same time .

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Does Sucrose Damage Kidneys?

“…tion either as a bolus or as an increment to diet (Blacklock and Macleod, 1974). Hypercalciuria also occurs after bolus ingestion of glucose in patients with renal hypercalciuria (Barilla et al, 1978).…”

A comparative study of two methods of measurement of fractional calcium absorption: results in normal individuals and patients with various disturbances of calcium metabolism

“…By means of comparing the radioactivity of orally administered 45Ca and intravenously given 47Ca in blood or urine samples it is possible to calculate the fractional calcium absorption by the gut [4, [8][9][10][11][12]. It is also possible to calculate the fractional calcium absorption as the ratio of the percentage radioactivity found after an intravenous and an oral dose, successively, using the same isotope [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] . Counting can be performed either on blood samples taken at intervals after oral and intravenous administration of radiocalcium [19,21,24,25,271 or with a so-called external counting method, with which, at the same intervals, part of the body is counted in a large volume scintillation counter.…”