Does Dietary Assessment Aid in Decision-Making for Medical Management of Hypercalciuria?
Management of hypercalciuria (?250 mg/d) to reduce stone risk may require dietary and/or medical therapy. Dietary advice is often based on 24-h urine results alone, without quantifying dietary calcium and/or other dietary factors. We quantified dietary contributors to hypercalciuria in our patients.
An investigator-designed questionnaire to assess habitual dietary intake of stone-related factors was completed by patients in our stone clinic; diet questionnaires were reviewed and analyzed by a registered dietitian. Results from the diet questionnaires were compared with each patient’s 24-h urine results. We excluded from analysis patients taking thiazides, potassium citrate, calcium, or vitamin D supplements. Patients whose 24-h urine collections appeared to be over- or under-collections were also excluded. Calcium and sodium intakes were compared with urinary calcium excretion.
Patients (n=62) were 53±13 yrs of age, and 40 (66%) were male. Mean dietary calcium was 1,054 mg/d (range 225-1,945 mg/d), and mean urine calcium was 250 mg/d (range 24-398 mg/d). Mean dietary sodium was 4,208 mg/d (range 2,032-7,696 mg/d), and mean urine sodium was 183 mEq/d (range 37-398 mEq/d). Most patients (61%) consumed <1,200 mg/d of calcium (the Recommended Dietary Allowance, RDA, for calcium is 1,000-1,200 mg/d for adults). Sodium intake for all patients (100%) exceeded the Adequate Intake (1,500 mg/d). When using the common risk cutoff for 24-h urine sodium (200 mEq = 4,600 mg/d), 44% consumed more than this. Nearly half (45%) of patients had hypercalciuria. Of these, calcium intake was >1,200 mg/d for 36% and < 1,000 mg/d for 50%. When patients with hypercalciuria were compared to those without (urine calcium <250 mg/d), there was no difference for intake of sodium (4,188 vs 4,223 mg/d, p=0.92) or calcium (1,053 vs 1,055 mg/d, p=0.99).
Our results reveal that one-third of patients with hypercalciuria exceeded the RDA for calcium intake, and less than half had sodium intakes >4,600 mg/d. Thus, in the majority of patients, neither calcium nor sodium restriction would be likely to address their hypercalciuria. An assessment of patients' diets, in conjunction with review of 24-h urine results, could help to rule in or out dietary contributors to hypercalciuria and avoid unnecessary dietary recommendations or restrictions.