Table 2.
Biochemical characteristics of Dutch XLH patients at inclusion in ORPHOS-NED
| Children N = 29 | Adults N = 51 | |
|---|---|---|
| Phosphate, mmol/L | 0.86 (0.21) | 0.66 (0.19) [50] |
| Hypophosphatemia, n(%) | 43 (86.0%) | |
| Phosphate Z-score | − 3.7 (1.6) | |
| Hypophosphatemia (< -2SD), n(%) | 27 (93.1%) | |
| Calcium, mmol/L | 2.37 (0.13) | 2.41 (0.17) [50] |
| Potassium, mmol/L | 4.1 (0.6) [12] | 4.1 (0.5) [39] |
| Sodium, mmol/L | 140 (1.8) [12] | 140 (2.0) [37] |
| Magnesium, mmol/L | 0.80 (0.07) [23] | 0.79 (0.08) [24] |
| Alkaline phosphatase, U/L | 398 (214) | 95 (44) [45] |
| Increased, n(%) | 13 (44.8%) | 20 (44.4%) |
| PTH | ||
| Normal, n(%) | 15 (51.7%) | 32 (74.4%) |
| Increased, n(%) | 7 (24.1%) | 9 (20.9%) |
| Unknown, n(%) | 7 (24.1%) | 2 (4.7%) |
| Missing, n(%) | – | 8 (15.7%) |
| 25(OH)D, nmol/L | 71.5 (33.3) [14] | 71.5 (33.3) [30] |
| Deficient, n(%) | 2 (14.3%) | 7 (23.3%) |
| 1,25(OH)2D, pmol/L | 166.5 (100.5) [24] | 79.0 (39.5) [5] |
| Low, n(%) | 1 (4.2%) | – |
| High, n(%) | 8 (33.3%) | – |
| cFGF23, RU/mL | 189 (191) [13] | 109 (97) [7] |
| Increased, n(%) | 11 (84.6%) | 3 (42.9%) |
| Creatinine, µmol/L | 38.0 (13.0) [28] | 59.0 (17.0) [50] |
| eGFR, ml/min/1.73 m2 a | 123.3 (38.5) [26] | 105.4 (27.1) [50] |
| < 60 ml/min/1.73 m2, n(%) | 2 (4.0%) | |
| P1NP, ng/mL | 817.5 (222.5) [10] | 69.5 (43.3) [26] |
| Increased, n(%) | 13 (50.0%) | |
| P1NP, Z-scores | 1.22 (1.44) [8] | – |
| > 2SD, n(%) | 2 (25.0%) | |
| Ctx, µg/L | 0.18 (0.14) [10] | 0.43 (0.30) [25] |
| Increased, n(%) | 8 (32.0%) | |
| CTx, Z-scores | 2.7 (3.4) [8] | – |
| > 2SD, n(%) | 5 (62.5%) | |
| BALP, U/L | 189.1 (62.7) [10] | 32.0 [1] |
| BALP, Z-scores | 4.4 (3.6) [9] | – |
| > 2SD, n(%) | 8 (88.9%) | |
| TmP/GFR, mmol/L; median(range) | 0.69 (0.22 to 1.48) [27] | 0.49 (0.18 to 0.58) [3] |
| < Age-related reference rangeb, n(%) | 25 (92.3%) | 3 (100%) |
| 24 h urine calcium, mmol/24 h; median(range) | 3.0 (2.2 to 3.8) [2] | 3.4 (0.6 to 14.5) [34] |
| Calcium/creatinine ratio, mmol/mmol (urine portion); median(range) | 0.83 (0.20 to 6.46) [29] | 1.13 (0.96–4.90) [4] |
Continuous values are displayed as median (interquartile range) unless otherwise stated, categorical variables are displayed in absolute counts (%). [n] indicates the number of patients in whom these parameters were available
25(OH)D 25-hydroxyvitamin-D, 1,25(OH)2D 1,25-dihydroxy-vitamin D, BALP bone-specific alkaline phosphatase, cFGF23 C-terminal fibroblast growth factor 23, CTx C-terminal telopeptide of type I collagen, eGFR estimated glomerular filtration rate, P1NP N-terminal propeptide of type 1 procollagen, PTH parathyroid hormone, TmP/GFR ratio of tubular maximum reabsorption of phosphate to glomerular filtration rate
aeGFR was calculated in adults based on the Chronic Kidney Disease Epidemiology Collaboration and in children based on the Chronic Kidney Disease in Children Under 25 equation
bThe age-related reference ranges for TmP/GFR were derived from Payne et al. [17]