Kidney Stone Risk Affected By Age and Sex

MedicalResearch.com Interview with:
Majuran Perinpam, BsC

Mayo Clinic
Rochester, Minn

MedicalResearch: What is the background for this study?

Response: The four key urinary factors: Calcium, magnesium, oxalate and uric acid are all implicated in kidney stone formation. Age and sex are known to influence kidney stone risk and type (1). However the effects of demographics on excretion of the four key urinary factors are not clear. Since diet alters urinary excretions of the four factors, adjusting for this is important. During metabolic evaluation of kidney stone patients, these urinary factors are often measured in 24-hour urine samples. However, often a single adult reference range is used and the effect of demographics is rarely taken into account during the interpretation of results.

MedicalResearch: What are the main findings?

Response: From a cohort of 709 healthy individuals we found a substantial influence of age and sex on the excretion of urinary calcium. Adjusted models showed that urinary calcium, magnesium, oxalate and uric acid were all less in females, possibly explaining why kidney stones are more dominant in males (1). Also a positive association of urinary uric acid excretion with Cystatin C eGFR, but not eGFR calculated from creatinine, suggests cystatin C to possibly being involved in inflammation and hyperuricemia. But further studies are needed to investigate this.

MedicalResearch: What should clinicians and patients take away from your report?

Response: In the evaluation of kidney stone patients, clinicians should take age and sex into account when interpreting lab values related to kidney stone risk, especially for urinary calcium. For example a urinary calcium level that might be average in a younger individual might be relatively high in an older one.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Response: Cystatin C has been proposed as a better marker for true eGFR than creatinine; however its association to urinary uric acid raises new questions that need further studies. Also urinary oxalate was higher in males than females despite no difference in oxalate intake, suggesting underlying biology as a cause and perhaps making males more prone to calcium oxalate stone formation by nature and requiring a different dietary approach to prevent recurrence.

Reference:

Lieske JC, Rule AD, Krambeck AE, Williams JC, Bergstralh EJ, Mehta RA, Moyer TP: Stone Composition as a Function of Age and Sex. Clin J Am Soc Nephrol, 2014

Citation:

Abstract Presented at the 2015 National Kidney Foundation Spring Meeting

LARGE EFFECT OF DEMOGRAPHICS ON URINARY RISK FACTORS FOR KIDNEY STONES
DOI: http://dx.doi.org/10.1053/j.ajkd.2015.02.213

MedicalResearch.com Interview with: Majuran Perinpam, BsC (2015). Kidney Stone Risk Affected By Age and Sex 

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