See how CRYSVITA may help your patients with XLH

27-year-old female with XLH*

Medical history

    During childhood

  • Age 5: evidence of rickets in wrists and knees along with delayed skeletal maturation; sister and father with known history of X-linked hypophosphatemia (XLH)
    • Diagnosed with XLH based on clinical and biochemical findings and family history
    • Initiated oral calcitriol and phosphate
    • Renal ultrasound indicated nephrocalcinosis; serum phosphorus was 2.4 (reference range 2.5 to 4.5 mg/dL); alkaline phosphatase was 538 U/L (reference range 100 to 300 U/L)
  • Age 7: radiographic evidence of rickets in lower limbs (see X-ray 1)
  • Age 8: stiffness and bone pain documented in pediatric records
  • Age 9 to 18: treatment for depression
  • Age 15 to 18: underwent bilateral hip surgery due to bilateral impingements and tibial osteotomy
  • No history of recombinant growth hormone use
  • Fracture history includes stress fracture of right femur, right ankle fracture, and left wrist fracture

    Transition to adult metabolic clinic, exam at age 25

  • Previously cared for in the pediatric endocrine clinic
  • Physical exam
    • Height, 4’11” (both mother and father, 5’2″)
    • No evidence of scoliosis
  • Reported stiffness, which made it difficult to get up from sitting positions or to stand for prolonged periods of time
  • Reported disabling bone and muscle pain; ongoing symptoms of childhood rickets complicated by depression; history of opiate dependence
  • Adherent to medical management with renal ultrasounds and 24-hour urine collections every 6 months

X-Ray 1: Rickets

  • At 7 years old: bilateral fraying of the metaphyses of the distal femurs; physeal widening

Diagnosis and initial treatment

  • Confirmed XLH diagnosis
  • Treatment: continue oral calcitriol and phosphate
  • Referral to integrative medicine

Disease progression

    Integrative medicine evaluation

  • Greatest patient-reported health concern: lower extremity pain (bilateral hips, knees, and ankles), which was experienced since early teens
    • Due to pain, transitioned jobs from a bedside nurse position into an administrative desk position
  • Reported anxiety and depression; expressed concerns with taking too many medications at a young age
    • Previously hospitalized for attempted suicide

    X-ray evaluation at age 26 (see X-ray 2)

  • Bilateral calcaneal enthesophytes; left Achilles enthesophyte previously broken
  • Small bilateral Haglund bumps with mild bilateral retrocalcaneal bursitis

    Metabolic clinic follow-up evaluation at age 27

  • Maintained adherence to prescribed XLH treatment; no change in dosage
  • Reported recent root canal for an abscess
  • Reported persistent pain
    • Recent Achilles tendon tear
    • Developed lower back pain
    • Developed pain in the anteromedial aspect of the right knee with prolonged walking, sit/stand transition, or using steps (see X-ray 3)
  • Referred to physical medicine and rehabilitation
  • Laboratory findings (see Table)
  • Initiated CRYSVITA treatment

    CRYSVITA treatment, 21 weeks

  • Patient reported resolution of stiffness and a return to work
  • Laboratory findings: tests improved (see Table)
  • Adverse reactions included mild injection site reactions (ISRs) and restless legs syndrome (RLS)
    • ISRs were treated with topical antihistamine medication
    • RLS resolved after 3 months

X-Ray 2: Enthesopathy

  • At 26 years old: bilateral calcaneal enthesophytes; previously broken left Achilles enthesophyte; small bilateral Haglund bumps with mild bilateral retrocalcaneal bursitis.

X-Ray 3: Right Knee Discomfort

  • At 27 years old: significant discomfort in the anteromedial aspect of the right knee with use. Proximal tibial osteotomy performed when patient was a teenager.

Laboratory test results

Test (reference rangea unit) Results (age)
Prior to CRYSVITA
(27 years)
CRYSVITA 21 weeks
(27 years)
Serum phosphorus (2.3-4.7 mg/dL) 1.2 3.1
1,25 (OH)2 (20-79 ng/mL) 31.4 73
25(OH)D (25-80 ng/mL) 36 30
BSAP (4.5-16.9 mcg/L) 21.3 19.2
PTH (16-88 pg/mL) 54 43
Creatinine (0.57-1.11 mg/dL) - 0.73
  • 1,25 (OH)2, 1,25 dihydroxy vitamin D; 25(OH)D, 25-hydroxy vitamin D (calcifediol); BSAP, bone-specific alkaline phosphatase, also known as BAP; PTH, parathyroid hormone.
  • 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

  • At age 5, patient was diagnosed with XLH; was compliant with conventional therapy of oral phosphate and calcitriol
  • XLH symptoms progressed from diagnosis: history of fractures, stiffness, pain, and impaired physical function
  • Disease progression in adulthood was managed by multiple specialties including endocrinology, integrative medicine, and physical medicine and rehabilitation
  • At age 27, patient initiated CRYSVITA; after 5 months demonstrated improvements in laboratory findings and joint stiffness
  • Adverse reactions associated with CRYSVITA treatment included ISRs and RLS; ISRs were treated with topical antihistamine, and RLS resolved after 3 months
  • *The information for this case study was provided courtesy of Dr. Kathyryn McCrystal Dahir, Professor of Medicine, Department of Endocrinology, Vanderbilt University Medical Center, Nashville. 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.

Laboratory test results

Test (reference rangea unit) Results (age)
Prior to CRYSVITA
(27 years)
CRYSVITA 21 weeks
(27 years)
Serum phosphorus (2.3-4.7 mg/dL) 1.2 3.1
1,25 (OH)2 (20-79 ng/mL) 31.4 73
25(OH)D (25-80 ng/mL) 36 30
BSAP (4.5-16.9 mcg/L) 21.3 19.2
PTH (16-88 pg/mL) 54 43
Creatinine (0.57-1.11 mg/dL) - 0.73
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X-Ray 1: Rickets

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At 26 years old: bilateral calcaneal enthesophytes; previously broken left Achilles enthesophyte; small bilateral Haglund bumps with mild bilateral retrocalcaneal bursitis.

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X-Ray 3: Right Knee Discomfort

At 27 years old: significant discomfort in the anteromedial aspect of the right knee with use. Proximal tibial osteotomy performed when patient was a teenager.

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