Calcium Kidney Stones

Abstract and Introduction

Introduction

Nephrolithiasis (kidney stones) occurs in more than 5% of the U.S. population and accounts for more than $5 billion in direct and indirect costs annually, related to hospitalization, surgery, and lost work time.^[1] The prevalence appears to be rising over time.^[2] The presence of nephrolithiasis is concentrated among working adults; about one-third of employees treated for nephrolithiasis miss work, averaging 19 hours per afflicted person. The incidence peaks in the third and fourth decades of life. By age 70 years, approximately 11% of men and 5.6% of women will have experienced a symptomatic kidney stone, and about 40% to 50% of initial stone formers will have a recurrence within 5 years.^[1,3] The risk of recurrence within 20 years is as high as 75%. Risk in white individuals is roughly three times higher than in the African American, Hispanic, and Asian American populations.^[4] Geographic location also appears to impact stone formation, with higher rates in the southeastern U.S., possibly related to greater sunlight exposure, resulting in increases in insensible fluid losses and increases in vitamin D production.

In addition to causing severe pain (renal colic) resulting in emergency room visits and sometimes hospitalization, stone formation is associated with increased rates of chronic kidney disease and hypertension.^[5,6]

The composition of a kidney stone can be determined by laboratory analysis after passage or surgical removal of the stone. Known varieties of stones include calcium oxalate, calcium phosphate, uric acid, magnesium ammonium phosphate (struvite), and cystine. About 70% to 80% of stones are composed primarily of calcium oxalate mixed with varying amounts of calcium phosphate.^[3] In the U.S., uric acid stones constitute about 10% of kidney stones. Struvite stones account for 10% to 15%, and cystine stones are quite rare, on the order of 1% of all stones.^[3] Since calcium stones are by far the most common, this paper will focus on that type.

Cite this: Calcium Kidney Stones - Medscape - Jun 01, 2011.

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