Infrared spectroscopy in kidney and biliary stone disease

Abstract

Nephrolithiasis is a complex, multifactorial disease resulting from an interaction between environmental and genetic factors. A minority of patients form stones because of well defined systemic diseases. In the rest, who usually are otherwise well expected for stone formation, the pathogenesis of stone is not as cleary defined. Compressive metabolic evaluation has become an important aspect of the management of recurrent nephrolithiasis, yet the role of stone analysis is often neglected or perhaps underestimated. The purpose of this study is to evaluate the chemical composition of kidney and biliary stones in our patients in order to provide guidance in metabolic evaluation and medical diagnosis, therapeutic treatment and prevention of recurrence. We used infrared spectroscopic method (Perkin Elmer Infrared Spectroscopy) to analyze the chemical composition of 224 kidney stones passed spontaneously or removed surgically and 40 gallstones removed surgically in the »Mother Teresa« University Hospital Centre of Tirana. Of 224 kidney stones 62% belong to male and 38% to female patients. Of infrared spectroscopic examinations of kidney stones 75.4% of results are calcium oxalate (CaOx) stones, 12.5% uric acid (UA) stones, 10.3% phosphate stones and 1.8% cystine stones. Of CaOx stones 67.4% are pure CaOx stones and 32.6% are mixed composition stones (CaOx mixed with UA or apatite). Of UA stones 82.1% are pure UA stones, 10.7% are UA stones mixed with ammonium urate and 7.2% are pure ammonium urate stones. Of phosphate stones 39.1% are of struvite composition, 26.1% are of carabapatite composition and 34.8% are of struvite composition mixed with apatite. The incidence of CaOx stones, UA stones and cystine stones is higher in men, while phosphate stones predominate in women. The chemical composition of 40 biliary stones examined with infrared spectroscopy is the following: 2.5% are pure calcium bilirubinate stones, are 42.5% are pure cholesterol stones and 55% are mixed stones (cholesterol stones mixed with calcium bilirubinate, calcite, aragonite or apatite). Females predominate in bilary stones. Calcium stones are the most frequent kidney stones. Calcium stones, uric acid stones and cystine stones were found more frequently in males than in females. On the other hand, phosphate containing stones, very often called »infection stones«, were more frequent in female patients. Cholesterol stones predominate in gallstones examined by infrared spectroscopy. All types of gallstones are more frequent in women than in men. Stone analysis alone may provide guidance for therapeutic treatment and recurrence prevention.