Urinary Biochemical profile in Urolithiasis: A case control study from Tamil Nadu

INTRODUCTION: Considerable progress has been made in the diagnosis and management of Urolithiasis but advances in our understanding of stone formation have not paralleled this. We still wonder why in a family some form stones while others don’t, though they are living in the same environment and consuming the same diet. The precipitating factor and sequence of events that lead to the formation of a kidney stone remains elusive. The likelihood of forming another stone after the first episode is about 10% at 1 year, 30-40% at 5 year, 50-60% at 10 years and possibly 95-100% at 20 to 25 years. AIM: Aim of the study was, to identify the differences in urinary profile of a stone former and matched member of the same family. MATERIALS AND METHODS: This study was conducted from April 2006 to January 2008 after taking approval from the institutional review board. Design of the study: This was a prospective matched Case-Control study. Informed consent (Annexure-i) for recruitment was obtained after a complete urological history (Annexure-ii) followed by serum and urinary examination. Seventy-eight subjects were recruited for the study (39 cases and 39 matched controls). Only patients from Tamilnadu were included in the study. Inclusion criteria for cases: • Eighteen years or older in age, • Patients who had renal or ureteric stones with normal renal function. Exclusion criteria for cases: • Patients with bladder stone, • Endocrine abnormality, • Anatomic urinary tract abnormality associated with stone formation, • History of bowel disease or resection predisposing to stone formation, • Medication and diseases associated with stone formation. Inclusion criteria for controls: • Eighteen years or older in age, • Same gender as of the patient, • First degree relation with the patient, • Diet matched relative–at least consuming two out of three major meals together, • No nephrolithiasis or history of stone disease, • Living in the family with the patient in the same house for at least last 5 years. Dietary matching was done with the help of the Dietary Department. Exclusion criteria for controls: • Those with urolithiasis or history of urinary stone disease, • Endocrine abnormality associated with stone formation, • History of bowel disease or resection predisposing to stone formation, • Medication and diseases associated with stone formation. OBSERVATIONS: Four hundred and fifty urolithiasis patients from Tamilnadu were evaluated from April 2006 to January 2008. Out of them 39 matched pairs were selected from urology clinic and lithotripsy unit, using preset inclusion and exclusion criteria. These clinics examine 700 stone patients annually from all parts of India. The mean age of the cases and controls was 38.5 years (Range 18-69 years) and 37.6 years (range 18-78 years) respectively. Out of 39 matched pairs, 25 (64%) were male and 14 (36%) were females. Thirty-one cases (79%) were first time stone formers and the rest had recurrence CONCLUSION: We conducted this study with a research question; do different people living in the same environment consuming the same diet have different urinary profile? We found urinary profile in family members of a stone patient is similar. It appears some other factor must have been present in stone formers and will require further research. At present the usefulness of uro-metabolic evaluation and subsequent therapy advice appears to have little value.