Medical Inspection – Health Blog

This man has the typical clinical and laboratory characteristics that are often found in recurrent formers of calcium kidney stones and a significant idiopathic hypercalciuria was particu­larly evident.

The diet to which he was subjected we define as “antilithogen- ic” because it takes into consideration all of the nutritional fac­tors which are known to provoke or promote a high calcium ex­cretion level. canadian medshop 247 cheap canadian drugs

Calcium nephrolitiasis is a disease which effects a high per­centage of people in industrialized nations and idiopathic hy- percalciuria (calcium excretion in excess of 300 mg/day in men and 250 mg/day in women) is the most frequent urinary stone risk factor.

There are various nutritional factors that act together for its genesis and all must be taken into consideration in order to ob­tain its correction, and to help in the prevention of stone recur­rences.

It has been known for some time that there is a positive rela­tionship between body weight and the excretion of calcium, so much so that some authors have proposed that calciuria be ex­pressed in relation to body weight, considering in this case a value of 4 mg/kg for both sexes as the limit used in the defini­tion of hypercalciuria. We too have seen in our patients (data not published) that even a modest increase in body weight is accompanied by a significant increase in calciuria and vicever- sa. But the proof that excess weight is an independent factor in stone risk was supplied in 1998 by Curhan et al.. These Au­thors subdivided 51,529 men into 5 categories in relation to their body weight and found that the percentage of stone form­ers increased with the increase in BMI: in particular, with BMI between 21 and 22.9 the percentage of stone formers was 7.1% and with a BMI greater than 32 the figure was 9.8% (a relative risk of 1.38). The same data were investigated in 89,376 women: with BMI of 21-22.9 the percentage of stone formers was 2.5%, with BMI > 32 the percentage of stone for­mers was 4.4% (a relative risk of 1.76). It is known that being overweight is often accompanied by arterial hypertension, as was the case with our patient, and it is possible that the two el­ements acting together explain the fact that the hypertensive subjects suffer from kidney stones more often, as first demon­strated by Tibblin in 1967. In keeping with this epidemiologi- cal survey, various authors have found that hypertensive sub­jects have a higher level of calcium excretion, compared to nor- motensive subjects, and a considerable percentage of them had marked hypercalciuria. We too have confirmed this da­ta also demonstrating, in a five-year follow-up, that hyperten­sive subjects have a much higher risk of stone formation than normotensive ones. Therefore, an overweight hypertensive subject has a higher probability of being hypercalciuric and he should reduce his body weight to the normal level and treat any hypertension, if necessary, with anti-hypertension drugs which reduce urinary calcium, such as thiazides or indapamide. Various Authors have shown that hypercalciuric stone formers have a high intestinal absorption of calcium and this was the basis for the habit of recommending a low-calcium diet (about 400 mg/day) with the removal of milk and its derivatives. However, over the years it has been observed that the low-cal­cium diet can lead to an increase in urinary oxalate and a negative calcium balance, with the consequent risk of osteoporosis, and without any clear advantage in terms of calci­um oxalate saturation levels. There are no long-term studies that have really shown that the low-calcium diet prevents re­lapses, but neither have they proved to be of no value. Howev­er, we have demonstrated in a randomized prospective 5-year study that the traditional low-calcium diet is less effective in the prevention of relapses in patients with hypercalciuria, in com­parison with a normal-calcium, low-sodium, low-protein and high-potassium diet. In this study we were able to ascertain that the calciuria is reduced with both of these treatments, but those that follow the low-calcium diet will always have a higher oxaluria than those following the other type of diet. In addition, Curhan et al., in two large epidemiological studies, one on men and the other on women were able to demonstrate that the prevalence of kidney stones is lower in people who con­sume more than 1 g dietary calcium per day. Therefore, bear­ing in mind what is currently known, the low-calcium diet should not be considered as the gold standard for the treat­ment of idiopathic hypercalciuria.