Explore the clinical results of CRYSVITA in children and adults with XLH
Case studies in X-linked hypophosphatemia (XLH)
Learn more about which patients could be appropriate for CRYSVITA®
(burosumab-twza)
Review these case studies to see how patients with XLH may present in clinical practice.*
Pediatric patient profile
4-year-old male with spontaneous XLH
At 20 months, this patient presented with hallmark signs of XLH, including bowed legs and a waddling gait. By age 2, he received a diagnosis and began conventional therapy—followed by enrollment in a CRYSVITA clinical trial.
Show description
Timeline of events for a 4-year-old male starting from birth. At 20 months, the patient presented with bowed legs and waddling gait. At 24-25 months, he was diagnosed with XLH and initiated oral calcitriol and phosphate. At 31 months, he was enrolled in the CRYSVITA® (burosumab-twza) clinical trial, and by 46 months, he had some improvement in symptoms.
Access the full case study for a closer look at his treatment journey and response over time.
Adult patient profile
37-year-old female with inherited XLH
Trace the lifelong clinical course of a woman with XLH—from diagnosis in early childhood to the emergence of progressive musculoskeletal symptoms in adulthood. See how treatment with CRYSVITA at age 36 led to early signs of improvement.
Show description
Timeline of events for a 37-year-old female starting from birth. At birth, no known abnormalities were detected. At 2 years of age, she was diagnosed with XLH, which was later confirmed by genetic testing when she was 13 years old. By 35 years of age, she began experiencing joint stiffness in her hips, knees, and ankles. When she was 36 years old, CRYSVITA® (burosumab-twza) therapy was initiated, and she began to experience some symptom improvement by 37 years of age.
Download the full case study to gain insights into long-term disease burden and treatment outcomes.
Pediatric patient profile
A 4-year-old male presented with symptoms at 20 months and underwent several specialty evaluations before being diagnosed with spontaneous XLH at 25 months.*
*This case is adapted from a real patient and is intended for illustrative purposes only, not as recommendations of care or management.
Show description
Timeline of events for a 4-year-old male starting from birth. At 20 months, the patient presented with bowed legs and waddling gait. At 24-25 months, he was diagnosed with XLH and initiated oral calcitriol and phosphate. At 31 months, he was enrolled in the CRYSVITA clinical trial, and by 46 months, he had some improvement in symptoms.
Medical history
- 20-month-old male presented with bowed legs
- Other physical exam findings: waddling gait, cannot run well
- Suspected diagnosis: physiologic bowing
- Exam at 24 months: worsened bowing of legs and waddling gait noted
- X-ray findings: bilateral bowing of femur and tibia; cupping of distal femur, proximal and distal tibia and fibula
- Suspected diagnosis: rickets
Evaluation at academic center
- Physical exam at 24.5 months: severe knee bowing, intercondylar distance of 5 cm, short stature, height in first percentile
- X-rays: metaphyseal flaring at wrists and ankles
- Laboratory findings (Table below)
- Suspected diagnosis: hypophosphatemic rickets
- Upon genetic evaluation at 25 months, pathologic PHEX variant identified; mother negative
| Test
(reference range†) |
Early evaluation
(24.5 months) |
Prior to CRYSVITA
(31 months) |
|---|---|---|
| Serum phosphorus1 (1 to <5 years: 4.3-6.8 mg/dL) |
2.9 | 2.9 |
| TmP/GFR2 (2 to 15 years: 3.6-7.6 mg/dL) |
N/A | 2.8 |
| 25(OH)D3 (0 to <18 years: 20-50 ng/mL) |
26 | 24 |
| ALP1 (1 to <10 years: 156-369 U/L) |
636 | 459 |
| Serum calcium1 (1 to <19 years: 9.2-10.5 mg/dL) |
9.4 | 9.5 |
| PTH3 (15-65 pg/mL) |
56 | 20 |
Test
(reference range† unit)
(reference range† unit)
Serum phosphorus
(1 to <5 years: 4.3-6.8 mg/dL)
(1 to <5 years: 4.3-6.8 mg/dL)
TmP/GFR‡
(2-15 years: 3.6-7.6)
(2-15 years: 3.6-7.6)
25(OH)D
(0 to <18 years: 20-50 ng/mL)
(0 to <18 years: 20-50 ng/mL)
ALP
(1 to <10 years: 156-369 U/L)
(1 to <10 years: 156-369 U/L)
Serum calcium
(1 to <19 years: 9.2-10.5 mg/dL)
(1 to <19 years: 9.2-10.5 mg/dL)
PTH
(15-65 pg/mL)
(15-65 pg/mL)
†Indicates values within the normal range for age and gender. Reference ranges may vary based on assay and instrument used. It is important to use the reference range provided by the laboratory conducting the test to ensure accuracy. Reference range values in this table were based on values presented in Colantonio et al. (2012), Dahir et al. (2021), and Payne et al. (1998), and may differ from ranges used at the time of evaluation.
25(OH)D=25-hydroxyvitamin D (calcifediol); ALP=alkaline phosphatase; PHEX=phosphate regulating endopeptidase homolog X-linked; PTH=parathyroid hormone; TmP/GFR=ratio of tubular maximum reabsorption of phosphorus to glomerular filtration rate.
Diagnosis and initial treatment
- Diagnosis: spontaneous XLH
- Treatment: oral calcitriol and phosphate
Evaluation post-diagnosis
- Physical exam at 29 months: femoral bowing; obvious genu varus—knees 4.5 cm apart, ankles touching; bilateral tibial bowing
- Height in fifth percentile
- X-rays: metaphyseal widening at wrists, mild cupping of distal radius and ulna
- Knees: marked bowing, cupping and fraying of growth plates
- Laboratory findings (Table above)
- Enrolled in CRYSVITA clinical trial at 31 months
Read the full case study here
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References:
- 1. Colantonio DA, Kyriakopoulou L, Chan MK, et al. Closing the gaps in pediatric laboratory reference intervals: a CALIPER database of 40 biochemical markers in a healthy and multiethnic population of children. Clin Chem. 2012;58(5):854-868. doi:10.1373/clinchem.2011.177741. 2. Payne RB. Renal tubular reabsorption of phosphate (TmP/GFR): indications and interpretation. Ann Clin Biochem. 1998;35(2):201-206. doi:10.1177/000456329803500208 3. Dahir K, Zanchetta MB, Stanciu I, et al. Diagnosis and management of tumor-induced osteomalacia: perspectives from clinical experience. J Endocr Soc. 2021;5(9):bvab099. doi:10.1210/jendso/bvab099
Adult patient profile
A 37-year-old woman was diagnosed with XLH as a toddler and suffered from XLH-associated symptoms throughout adulthood, including fractures, joint stiffness, and pain.*
*This case is adapted from a real patient and is intended for illustrative purposes only, not as recommendations of care or management.
Show description
Timeline of events for a 37-year-old female starting from birth. At birth, no known abnormalities were detected. At 2 years of age, she was diagnosed with XLH, which was later confirmed by genetic testing when she was 13 years old. By 35 years of age, she began experiencing joint stiffness in her hips, knees, and ankles. When she was 36 years old, CRYSVITA therapy was initiated, and she began to experience some symptom improvement by 37 years of age.
Medical history
- Age 2: Diagnosed with XLH
- Initiated oral phosphate and calcitriol and was compliant
- Age 13: XLH diagnosis was confirmed by genetic testing
Family history
- Mother and maternal grandmother had XLH
XLH symptoms and associated complications in adulthood
- Chiari malformation requiring 2 corrective surgeries
- Chronic ankle pain and swelling in joints
- Gait abnormalities
- Sustained pelvic fracture during childbirth
- Age 33: discontinued oral phosphate and calcitriol
Evaluation prior to CRYSVITA
- Age 35: presented to adult endocrinology with bowing of lower extremities and joint stiffness in hips, knees, and ankles
- Physical exam
- Height, 5’2”
- Required the use of assistive walking device (cane) for long distances and handicap tags due to mobility challenges
- Tinnitus in right ear
- Calcifications noted on prior renal ultrasound
- Laboratory findings (Table below)
- Physical therapy evaluation
- Required assistance to rise from seated to standing position
- Tight hip flexors; limited range of motion in hips
- X-rays
- Prominent enthesophytes associated with the calcaneus bilaterally as well as ankle and midfoot arthritis
- Hypertrophic bone formation occurring at the hip articulation and trochanters; sclerosis at the sacroiliac joints
- Degenerative changes of the knees including bilateral articular surface irregularities of the femoral condyles
- Bones diffusely demineralized and bilateral narrowing of joint space compartment also noted
| Test
(reference range†) |
Early evaluation
(35 years) |
|---|---|
| Serum phosphorus1 (2.5-4.5 mg/dL) |
1.6 |
| 1,25(OH)2D1 (female: 18-72 pg/mL) |
40.3 |
| 25(OH)D2 (20-50 ng/mL) |
35 |
| BSAP3 (2.9-14.5 µg/L) |
25 |
| PTH1 (14-72 pg/mL) |
55 |
| Creatinine4 (female: 0.50-1.10 mg/dL) |
0.74 |
Test
(reference range†)
(reference range†)
Serum phosphorus1
(2.5-4.5 mg/dL)
(2.5-4.5 mg/dL)
1,25(OH)₂D1
(female: 18-78 pg/mL)
(female: 18-78 pg/mL)
25(OH)D2
(20-50 ng/mL)
(20-50 ng/mL)
BLAP3
(premenopausal: 2.9-14.5 µg/L)
(premenopausal: 2.9-14.5 µg/L)
PTH1
(14-72 pg/mL)
(14-72 pg/mL)
Creatinine4
(female: 0.50-1.10 mg/dL)
(female: 0.50-1.10 mg/dL)
†Indicates values within the normal range for age and gender. Reference ranges may vary based on assay and instrument used. It is important to use the reference range provided by the laboratory conducting the test to ensure accuracy. Reference range values in this table were based on values presented in Dahir et al. (2021), Imel et al. (2015), Portale et al. (2019), and data on file, and may differ from ranges used at the time of evaluation.
1,25(OH)2D=1,25 dihydroxyvitamin D; 25(OH)D=25-hydroxyvitamin D (calcifediol); BALP=bone-specific alkaline phosphatase, also known as BSAP; PTH=parathyroid hormone.
Diagnosis and initial treatment
- XLH diagnosis reconfirmed
- Treatment: CRYSVITA
See the full case study here
DownloadLearn how CRYSVITA helped adult patients in clinical trials
Set up time with a representative to talk more about CRYSVITA
References:
- 1. Portale AA, Carpenter TO, Brandi ML, et al. Continued beneficial effects of burosumab in adults with X-linked hypophosphatemia: results from a 24-week treatment continuation period after a 24-week double-blind placebo-controlled period. Calcif Tissue Int. 2019;105(3):271-284. doi:10.1007/s00223-019-00568-32. Dahir K, Zanchetta MB, Stanciu I, et al. Diagnosis and management of tumor-induced osteomalacia: perspectives from clinical experience. J Endocr Soc. 2021;5(9):bvab099. doi:10.1210/jendso/bvab0993. Imel EA, Glorieux FH, Whyte MP, et al. Burosumab versus conventional therapy in children with X-linked hypophosphataemia: a randomised, active-controlled, open-label, phase 3 trial. Lancet. 2019;393(10189):2416-2427. doi:10.1016/S0140-6736(19)30654-34. Data on file. 304 EOS CSR. Ultragenyx Pharmaceutical Inc.; 2019.
*These case studies are adapted from real patients and are intended for illustrative purposes only, not as recommendations of care or management.
Cora and Aly,
on CRYSVITA since 2018
