A spectroscopic study of thalassemic gallstones

Abstract

The chemical composition of a suite of pigment gallstones obtained from patients suffering from β-thalassemia was studied using FTIR, FT-Raman, and Mossbauer spectroscopies with a view to gaining a better understanding of their complex composition and developing an effective characterization procedure. The combination of vibrational spectroscopic techniques such as FTIR and FT-Raman make it possible to identify the major chemical components of thalassemic pigment stones and to subcategorize them for further study. All but one sample had almost identical FTIR spectra where bands attributable to both cholesterol and various bilirubinate salts were observed. One sample, low in cholesterol, showed, distinctive spectral peaks of calcitic CaCO3. This sample was sufficiently high in iron for Mossbauer spectroscopy, which showed, at room temperature, a quadrupole-split doublet consistent with the presence of iron (III). This concomitant presence of iron and a high CaCO3/low cholesterol content has, as far as we are aware, not been previously reported. When studied by FT-Raman, however, most of the stones gave spectra typical of previously characterized brown stones. Due to the limited number of stones available, in particular iron-rich samples, further work is required, but these preliminary results indicate that it may in fact be possible to unequivocally categorize thalassemic stones into different types using spectroscopic techniques. Together with FTIR and Raman microscopy of cut stones, such nondestructive spectroscopic techniques show promise in helping researchers gain an understanding of thalassemic stone formation and occurrence. In addition, the samples are maintained for further study, which is important considering the difficulty in establishing large suites of such special category stones.