Leone Fedeli

Classification of idiopathic hypercalciuric patients by isotopic calcium absorption: a comparison with oral calcium tolerance test

SummaryTo test the accuracy of calcium tolerance test in estimating calcium absorption, we have measured the radioactive calcium absorption (expressed as Fx) in 27 patients with IH and renal calcium stones. The results of this test were compared with those of a standard oral calcium tolerance test. Although only seven of nine AH patients displayed normal fasting calcium excretion, they all displayed Fx values above normal and a normal parathyroid activity. Conversely, only 5 of our 18 RH patients demonstrated a hyperabsorption of radioactive calcium and an elevation in iPTH and cAMP above normal limits, yet all of them showed an increased calciuric response to an oral calcium challenge. Calcium absorption was inversely related to iPTH (r=−082;P<0.001) and cAMP (r=−064P<0.05) in AH, but directly proportional to these parameters (r=0.62P<0.001 andr=0.46P<0.05, respectively) in RH patients.In view of these results, two ratios, iPTH/Fx and cAMP/Fx were used to discriminate between the two groups of patients. Both ratios were over normal limits in all RH patients and within normal range in all but one AH patient. Furthermore, no overlap was found between the two groups. Conversely, we were unable to completely separate AH from RH subjects on the basis of the oral calcium tolerance test, since in both groups the fasting and the absolute (or percentage) changes in urinary calcium, cAMP and blood iPTH levels following oral calcium loading, overlapped in each instance. The result of this study indicates that two indices, iPTH/Fx and cAMP/Fx, may prove particularly useful in differentiating AH from RH patients. Furthermore, since only a subgroup of patients with an abnormal calciuric response to an oral calcium load manifest an increase in calcium absorption, it is concluded that the calcium tolerance test overestimates calcium absorption in IH.

Elevation of serum bile acids induced by sodium fusidate administration in man

To The Editor: Dr. Dobbins has reviewed excellently the subject of immunological studies in Whipples disease in the March issue of your journal (1). He suggests, in the concluding remarks, that Whipples bacillus may be an intracellular pathogen similar to Listeria or Salmonella. Our recent observations on antibacterial immunofluorescent reactions in macrophages from a patient with Whipples disease show discrete fluorescence only with antisera to group H Listeria and no fluoresence with antisera to group O Listeria or antipolyvalent Salmonella (2). Thereafter we confirmed the antigenic similarity of the polysaccharide to group B and A Streptococcus and to Shigellaflexneri (3-4). However, it must be remembered that our patient was from a different continent. Secondly, Dr. Dobbins accepted that severe malnutrition and partial obstruction of intestinal lymphatics might account for all the changes in immune function seen in the untreated patient. However, he also considered that immune responses to intracellular pathogens are complex and should be studied further. I agree that immune dysfunction may be a consequence of the persistence of intracellular bacterial antigen and may be terminated by removal of the antigen, resulting from the successful treatment of the infection (5). The subtle defect of cell-mediated immune function observed in some treated patients may be related to the persistence of some antigenloaded macrophages in the lamina propria, as observed in most of the patients studied by Martin (6). The difference between the various studies on immunologic function may be related to the timing of the sampling and are probably, in part, explained by lack of proper histopathologicaI correlations. F. TAVARELA VELOSO Department of Gastroenterology University Hospital of S. Jo(to Porto, Portugal