Table 1.
Baseline characteristics of study population
| Characteristics | Study participants (N = 974) |
|---|---|
| Males | 677 (69.5%) |
| Age, y | 47.5 (14.4) |
| Age at first self-reported stone event, y | 36.9 (14.2) |
| Age at first stone composition analysis, y | 45.8 (14.6) |
| Body mass index, kg/m2 | 27.1 (4.9) |
| eGFR creatinine Equation CKD-EPI 2009, ml/min per 1.73 m2 BSA | 95.0 (19.7) |
| Hypertension medication usage | 268 (27.6%) |
| Diabetes | 114 (11.7%) |
| Stone recurrence (≥2 stone events) | 793 (81.3%) |
| Medications affecting plasma 25(OH) vitamin D3 | 71 (7.3%) |
| Loop diuretics | 14 (1.4%) |
| Thiazide diuretics | 127 (13.0%) |
| DEXA parameters | |
| Femoral neck BMD, g/cm2 | 0.83 (0.75, 0.93) |
| Femoral neck T-score, SD | −0.60 (−1.30, 0.00) |
| Lumbar spine BMD, g/cm2 | 1.01 (0.93, 1.11) |
| Lumbar spine T-score, SD | −0.60 (−1.40, 0.30) |
| Blood parameters | |
| Total plasma calcium, mmol/l | 2.34 (2.28, 2.39) |
| Corrected plasma calcium, mmol/l | 2.36 (2.30, 2.42) |
| Ionized calcium, mmol/l | 1.20 (1.17, 1.22) |
| Phosphate, mmol/l | 0.99 (0.87, 1.11) |
| 25(OH) vitamin D3, ng/ml | 21.00 (14.00, 29.00) |
| 1,25(OH)2 vitamin D3, pmol/l | 99.00 (74.79, 127.00) |
| Total 24,25(OH)2 vitamin D ng/ml | 1.46 (0.73, 2.30) |
| VMDR | 14.78 (11.51, 19.67) |
| Intact PTH, ng/l | 39.00 (30.60, 50.00) |
| cFGF23, RU/ml | 69.50 (54.35, 96.00) |
| Urinary parameters | |
| Urinary calcium, mmol/24h | 5.14 (3.33, 7.48) |
| Fractional excretion of calcium, % | 2.72 (1.79, 3.57) |
| RSS for calcium oxalate | 4.08 (2.05, 7.62) |
| RSS for brushite | 0.74 (0.27, 2.06) |
| Relative kidney stone composition ≥50% | |
| Available stone composition analysis | 751 (77.1%) |
| Total calcium oxalate | 595 (79.2%) |
| Calcium oxalate monohydrate | 399 (54.0%) |
| Calcium oxalate dihydrate | 132 (17.9%) |
| Total calcium phosphate | 91 (12.1%) |
| Apatite | 63 (8.4%) |
| Brushite | 15 (2.0%) |
| Uric acid | 60 (8.0%) |
| Cystine | 9 (1.2%) |
BKSR, Bern Kidney Stone Registry; BMD, bone mineral density; BSA, body surface area; cFGF23, C-terminal fibroblast growth factor 23; CKD-EPI, Chronic Kidney Disease-Epidemiology Collaboration; DEXA, dual-energy X-ray absorptiometry; eGFR, estimated glomerular filtration rate; PTH, parathyroid hormone; SKSC, Swiss Kidney Stone Cohort; VMDR, Vitamin D metabolite diagnostic ratio.
Characteristics are indicated for all participants enrolled from the BKSR and the SKSC. Categorical variables are described by number of participants N (%), continuous variables are described by their mean (SD) or median (25th–75th percentile).