Table 3.
Baseline biochemical studies.
| Children | Adults | |||||
|---|---|---|---|---|---|---|
|
No NC
n = 152 |
NC
n = 44 |
Total
n = 196 |
No NC
n = 196 |
NC
n = 122 |
Total
n = 318 |
|
|
Serum phosphorus
Patients below LLN, n (%) |
n = 150 148 (99) |
n = 44 42 (96) |
n = 194 190 (98) |
n = 195 155 (79) |
n = 122 109 (89) |
n = 317 264 (83) |
| Below LLN: p=.19 | Below LLN: p<.05 | |||||
|
mg/dL, mean (SD)
median |
2.5 (0.5) 2.5 |
2.4 (0.5) 2.3 |
2.5 (0.5) 2.5 |
2.2 (0.4) 2.2 |
2.0 (0.4) 2.0 |
2.1 (0.4) 2.1 |
| Mean: p=.06 | Mean: p<.01 | |||||
|
Z-score, mean (SD)
median |
−4.2 (0.8) −4.3 |
−4.2 (1.0) −4.5 |
−4.2 (0.8) −4.4 |
|||
|
TmP/GFR
Patients below LLN, n (%) |
n = 75 73 (97) |
n = 31 31 (100) |
n = 106 104 (98) |
n = 68 65 (96) |
n = 90 87 (97) |
n = 158 152 (96) |
| Below LLN: p=.52 | Below LLN: p=.73 | |||||
|
mg/dL, mean (SD)
median |
2.1 (0.4) 2.2 |
1.9 (0.4) 1.9 |
2.1 (0.4) 2.0 |
1.7 (0.4) 1.7 |
1.7 (0.4) 1.7 |
1.7 (0.4) 1.7 |
| Mean: p<.05 | Mean: p=.24 | |||||
|
Serum calcium
Patients above ULN, n (%) mg/dL, mean (SD) median |
n = 110 5 (5) 9.6 (0.4) 9.6 |
n = 35 6 (17) 9.9 (0.5) 9.8 |
n = 145 11 (8) 9.7 (0.5) 9.7 |
n = 99 3 (3) 9.3 (0.5) 9.2 |
n = 100 0 (0) 9.2 (0.5) 9.1 |
n = 199 3 (2) 9.2 (0.5) 9.1 |
| Mean: p<.05 | Mean: p=.13 | |||||
|
Serum iPTH
Patients above ULN, n (%) pg/mL, mean (SD) median |
n = 147 31 (21) 50.1 (34.0) 42.1 |
n = 44 10 (23) 49.0 (30.4) 44.1 |
n = 191 41 (22) 49.9 (33.1) 42.5 |
n = 195 102 (52) 85.3 (50.1) 76.0 |
n = 121 76 (63) 94.3 (73.6) 82.0 |
n = 316 178 (56) 88.8 (60.2) 78.0 |
| Mean: p=.84 | Mean: p=.20 | |||||
|
ALP
Patients above ULN, n (%) U/L, mean (SD) median |
n = 147 121 (82) 474 (167) 467 |
n = 44 34 (77) 431 (122) 438 |
n = 191 155 (81) 464 (159) 464 |
n = 104 52 (50) 120 (47) 112 |
n = 100 46 (46) 132 (87) 107 |
n = 204 98 (48) 126 (70) 110 |
| Mean: p=.11 | Mean: p=.20 | |||||
|
1,25(OH)
2
D
Patients below LLN pg/mL, mean (SD) median |
n = 141 75 (53) 46.4 (18.9) 43.5 |
n = 42 29 (69) 36.9 (16.9) 35.0 |
n = 183 104 (57) 44.2 (18.7) 41.4 |
n = 182 32 (18) 40.6 (16.6) 39.1 |
n = 115 36 (31) 36.7 (17.1) 34.5 |
n = 297 68 (23) 39.1 (16.8) 37.6 |
| Mean: p<.05 | Mean: p<.05 | |||||
|
25OHD
Patients <30 ng/mL, n (%) Patients <20 ng/mL, n (%) ng/mL, mean (SD) median |
n = 94 43 (46) 9 (10) 31.2 (9.7) 30.8 |
n = 31 10 (32) 2 (7) 32.6 (10.2) 32.4 |
n = 125 53 (42) 11 (9) 31.6 (9.8) 31.3 |
n = 68 49 (72) 22 (32) 24.2 (8.7) 24.1 |
n = 90 59 (66) 30 (33) 25.8 (12.1) 24.1 |
n = 158 108 (68) 52 (33) 25.1 (10.8) 24.1 |
| Mean: p=.51 | Mean: p=.36 | |||||
Abbreviation:ALP, alkaline phosphatase; iPTH, intact parathyroid hormone; LLN, lower limit of normal; NC: nephrocalcinosis; TmP/GFR, tubular maximum for phosphate reabsorption per GFR; ULN, upper limit of normal.
Nephrocalcinosis was defined as a renal ultrasound score ≥1. Two-sided t-tests were used to compare mean values, and chi-squared tests were used to compare the percentage of patients below the LLN in children with nephrocalcinosis vs children without nephrocalcinosis and adults with nephrocalcinosis vs adults without nephrocalcinosis. Normal ranges are shown in Supplemental Table 2