How useful is an oral calcium load test for diagnosing recurrent calcium stone formers?

Abstract

Hypercalciuria is the main risk factor for recurrent calcium urolithiasis. The goal of our study is to determinate how useful an oral calcium load test is for stone formers to classify different forms of hypercalciuria in pathogenetic categories defined as renal or absorptive according to the current knowledge. Between June 2013 and February 2016, a prospective study was carried out on 117 documented recurrent hypercalciuric stone formers undergoing an oral calcium load test modified from the original description by Pak. After 2 days of calcium-restricted diet, urine and blood were analyzed at baseline and 120 min after receiving orally 1 g of calcium. Total and ionized calcium, parathyroid hormone from serum and urine calcium and creatinine were assessed in order to divide patients in three groups as previously described: resorptive, absorptive, and renal hypercalciuria. This allowed the identification of 19, 39, 34 and 33 patients with normocalcemic primary hyperparathyroidism (NPHPT), renal hypercalciuria aka renal calcium leak (RCL), absorptive hypercalciuria (AH) and unidentified cause, respectively. Patients with NPHPT (who required parathyroidectomy) experienced a lower PTH decrease (41.41 ± 12.82 vs. 54.06 ± 13.84% p < 0.01), higher beta-crosslaps, as well as lower TmP/GFR and distal third radius bone mineral density. RCL resulted in increased fasting urine calcium-to-creatinine ratio (Uca/Cr), i.e., > 0.37 mmol/mmol), without hyperparathyroidism. AH was diagnosed by the presence of ΔUCa/Cr > 0.60 mmol/mmol between baseline and 120 min without any other anomaly. For all remaining patients, results were inconclusive due to the lack of sufficient increase in serum calcium or because the cause of lithogenesis could not be clearly identified. The oral calcium load test is useful in nearly 80% of patients by identifying the different forms of hypercalciuria causing urolithiasis and by guiding treatment, including parathyroid surgery.

Bone mineral density and Trabecular Bone Score in patients with kidney stone disease

“…At the same time, calciuria is one of the frequent causes of nephrolithiasis and is associated with a decrease in BMD, and its absence is associated with a lower risk of fractures and a higher BMD [11]. Violation of calcium ho meostasis is one of the leading links in the pathogenesis of some pathology, such as osteoporosis, nephrolithiasis, and is associated with cardiovascular pathology (vascular calci fication and arrhythmias) [12]. Questionnaires conducted in research indicate an association between low calcium in take and increased calciuria [13].…”

“…Population 80 patients took part in the study, 14 men (17.5 %) and 64 women (82.5 %) among them. The median age of the patients was 58 [IQR 49-64] years; the median duration of menopause in women was [12][13][14][15][16][17][18][19][20] years.…”

“…years). The median duration of menopause in women was [12][13][14][15][16][17][18] years. The second group in cluded the subjects without KSD (32 persons,31 (96.88 %) women, and 1 (3.12 %) man, median age 63.2 ] years).…”

Analysis of Bone Mineral Density, Bone Tissue Quality Index (TBS) and Salt Transport in Patients with Nephrolithiasis

“…Тому для досягнення цієї мети кальційвмісні препарати та продукти харчування рекомендовано включати в денний раціон. Водночас кальційурія є однією з частих причин нефролітіазу та асоціюється зі зниженням МЩКТ, а її відсутність -з нижчим ризиком переломів та більш високою МЩКТ [15].…”