See how CRYSVITA may help your patients with XLH

5-year-old female with spontaneous XLH*

Medical history

    Orthopedic evaluation

  • 19-month-old female presented with hip clicks
    • X-ray findings: normal hips

    Endocrinology evaluation

  • Physical exam at 24 months: waddling gait, mild bowing at knees, no pain
    • Reported poor weight gain: from 25th percentile at 9 months to between 3rd and 5th percentile at 23 months
    • Walking delayed until 18 months
    • No family history of rickets
  • Laboratory findings (see Table)
  • Suspected diagnosis: probable vitamin D deficiency rickets; possible intestinal malabsorption; additional laboratory testing performed
    • Recommended management: cholecalciferol and increased calorie intake

    Nephrology evaluation

  • Physical exam at 26 months: frontal bossing, waddling gait, prominent costochondral junctions, genu varus, bilateral tibial bowing; intercondylar distance 12.7 cm with ankles touching
  • X-rays: metaphyseal flaring and cupping of the distal femoral and proximal and distal tibial and fibular metaphyses with varus bowing of the bilateral femurs, tibias, and fibula; and bilateral genu varum compatible with rickets (see X-rays)
  • Laboratory findings (see Table)

Growth Chart

  • Patient growth evolution prior to and after CRYSVITA.
    A: At 26 months, the patient was in the 3rd to 5th percentile for height.
    B: At enrollment, the patient was in the 10th percentile for height.
    C: While on CRYSVITA, the patient was between the 10th and 15th percentile for height.
  • The reference percentiles on the graph are combined from the two clinical growth charts for girls 2-20 years of age provided by the Centers for Disease Control and Prevention.

Diagnosis and initial treatment

  • Hypophosphatemic rickets, probable XLH
  • Treatment: oral calcitriol and phosphate

Disease progression

    Evaluation at academic center

  • Physical exam at 37 months: wide-based gait, genu varus with intercondylar distance 2.5 cm; bilateral tibial bowing greater on the right than the left
  • X-rays: mild metaphyseal widening at wrists
  • Laboratory findings (see Table)
  • Enrolled in CRYSVITA clinical trial

    CRYSVITA treatment, 106 weeks

  • Physical exam at 63 months: knees touching; mild tibial bowing on right
  • X-rays: mild bowing of femurs; considerable improvement in varus (see X-rays)
  • Laboratory findings: tests improved (see Table)

X-rays: Evolution of Rickets and Lower Limb Deformity

Early evaluation
(26 months old)

Prior to CRYSVITA
(37 months old)

CRYSVITA 40 weeks
(47 months old)

CRYSVITA 64 weeks
(53 months old)

CRYSVITA 106 weeks
(63 months old)

Laboratory test results

Test (reference rangea unit) Results (age)
Early evaluation
(24 months)
Early evaluation
(26 months)
Prior to CRYSVITA
(37 months)
CRYSVITA 40 weeks
(47 months)
CRYSVITA 64 weeks
(53 months)
CRYSVITA 106 weeks
(63 months)
Serum phosphorus (4.3-6.8 mg/dL) 2.7 3.0 2.5 3.7 3.4 3.9
TmP/GFR (4.0-5.2 mg/dL) n/a 2.5 2.15 n/a 2.79 3.91
25(OH)D (≥20 ng/mL) 27 n/a 40 n/a 30 n/a
ALP (156-369 U/L) 487 502 528 369 232 295
Serum calcium (9.2-10.5 mg/dL) 9.9 9.8 9.3 9.2 8.9 9.4
PTH (10-65 pg/mL) 48 n/a 33 31 44 n/a

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  • 25(OH)D, 25-hydroxy vitamin D (calcifediol); ALP, alkaline phosphatase; PTH, parathyroid hormone; TmP/GFR, ratio of tubular maximum reabsorption of phosphate to glomerular filtration rate.
  • aIndicates normal range, age, and sex matched. Note that normal range values may vary depending on reference dataset. The range in this table was provided by the treating physician.

Summary

  • Patient presented with symptoms at 19 months and underwent several specialty evaluations before XLH diagnosis at 26 months
  • Conventional therapy initiated; XLH symptoms continued to progress
  • Patient enrolled in CRYSVITA clinical trial at 37 months
  • After 106 weeks on CRYSVITA, patient demonstrated improvements in laboratory findings and lower limb deformity
  • *The information for this case study was provided courtesy of Dr. Anthony Portale, Director of the Pediatric Dialysis Program, UCSF Benioff Children’s Hospital, San Francisco. This case study represents a real patient and is intended to be illustrative, not a recommendation for treatment or management. Not all patients will respond the same to CRYSVITA treatment. Results may vary. This case study does not claim to represent typical results.
Reference
  1. Centers for Disease Control and Prevention. Clinical growth charts. Centers for Disease Control and Prevention website. https:www.cdc.gov/growthcharts/clinical_charts.htm. Last reviewed June 16, 2017. Accessed July 11, 2019.

Growth Chart

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Laboratory test results

Test (reference rangea unit) Results (age)
Early evaluation
(24 months)
Early evaluation
(26 months)
Prior to CRYSVITA
(37 months)
CRYSVITA 40 weeks
(47 months)
CRYSVITA 64 weeks
(53 months)
CRYSVITA 106 weeks
(63 months)
Serum phosphorus (4.3-6.8 mg/dL) 2.7 3.0 2.5 3.7 3.4 3.9
TmP/GFR (4.0-5.2 mg/dL) n/a 2.5 2.15 n/a 2.79 3.91
25(OH)D (≥20 ng/mL) 27 n/a 40 n/a 30 n/a
ALP (156-369 U/L) 487 502 528 369 232 295
Serum calcium (9.2-10.5 mg/dL) 9.9 9.8 9.3 9.2 8.9 9.4
PTH (10-65 pg/mL) 48 n/a 33 31 44 n/a

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