Table 1 Laboratory evaluation of patients at the time of evaluation was notable for hypophosphatemia, low to low-normal 1,25-dihydroxyvitamin D level, and elevated fibroblast growth factor 23 (FGF23) level. Abnormal laboratory values are annotated with (H) if above the normal range and (L) if below the normal range

Serum phosphorus (2.7–4.6 mg/dL)

1.7 (L)

1.0–1.5 (L)

1.3–1.5 (L)

2.1 (L)

Serum creatinine (0.5–1.0 mg/dL)

0.85

0.85

0.87

0.97

Serum calcium (8.6–10.3 mg/dL)

10.0

9.4

9.9

9.0

Serum albumin (3.5–4.9 g/dL)

4.6

4.5

4.3

4.0

Intact parathyroid hormone

(10–65 pg/mL)

25

61

113 (H)

46

25-hydroxyvitamin D

(25–100 ng/mL)

52

18 (L)

24 (L)

27

1,25-dihydroxyvitamin D

(18–78 pg/mL)

18

7 (L)

13 (L)

20

Alkaline phosphatase (40–116 IU/L)

145 (H)

262–278 (H)

246–326 (H)

441 (H)

Plasma FGF23 (< 180 RU/mL)

264 (H)

540 (H)

2189 (H)

548 (H)