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49-YEAR-OLD MALE WITH XLH*

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  • During childhood
    • 6 years of age: humerus fracture from jumping off a moving truck
    • Poor dentition of both primary and secondary teeth with multiple cavities and abscesses
    • 11 years of age: reported “bone disease” due to chronic bone and joint pain
      • Pediatrician diagnosed post-streptococcal arthritis
    • Mild leg bowing; reported short stature compared to peers
  • Early to mid-twenties
    • Lost most teeth by early twenties
    • Acute worsening of bone and joint pain
      • Suspected inflammatory arthritis; treated with anti-inflammatory medication
  • 44 years of age
    • Presented with acute exacerbation of chronic weakness and right hip pain
      • Required the use of prescription pain medication, including hydrocodone acetaminophen
    • Reported no previous diagnosis of rickets or any medical management of low phosphorus
    • Family history
      • Short stature and bowing of the lower legs in mother (height, 4’11”), three brothers, and two nieces; all had multiple fractures
    • Physical exam
      • Height, 5’3”; weight, 230 lbs
      • Ambulating with assistance of a walker; knees in varus alignment
      • Pain with internal rotation of hips (left worse than right); 4/5 motor strength in both proximal and distal muscle groups
      • Poor dentition and missing most secondary teeth
    • X-rays
      • Pelvis and hips: diffuse increased density of the bones, particularly in the iliac wings and lumbosacral spine; enthesopathic calcifications extending from the superior acetabular walls bilaterally (See X-ray 1); right subtrochanteric pseudofracture identified, which was incomplete along the medial cortical region (See X-ray 2)
      • Femurs: pseudofractures in the subtrochanteric right femur and mid-left femoral diaphysis; healing stress fracture present in the medial cortex of the left femoral neck; enthesophytes and bilateral hip osteoporosis also noted (See X-ray 3)
    • Laboratory findings (See Table)

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X-ray 1: Disease Progression
In Pelvis And Hips
49-year-old male X-ray of disease progression in pelvis and hips due to X-linked hypophosphatemia
44 years of age: Diffuse increased density of lilac wings and lumbosacral spine; bilateral enthesopathic calcifications extending from the superior acetabular walls.

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X-ray 2: Subtrochanteric
Pseudofracture
49-year-old male X-ray of subtrochanteric pseudofracture
44 years of age: Right subtrochanteric pseudofracture (arrow) incomplete along the medial cortical region.

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X-ray 3: Pseudofractures
In Femurs
49-year-old male X-ray of pseudofractures in femurs
44 years of age: Pseudofractures in the subtrochanteric right femur (arrow) and mid-left femoral diaphysis (arrow head); healing stress fracture present in left femoral neck medial cortex; enthesophytes and bilateral hip osteoporosis.
  • X-linked hypophosphatemia (XLH)
  • Treatment: calcitriol and phosphorus supplementation
The patient exhibited XLH signs and symptoms throughout childhood and young adulthood and was not diagnosed until his mid-forties.
  • 44 years of age: after XLH diagnosis, under went left hip replacement surgery
    • Developed worsening right hip pain; underwent right hip replacement surgery 3 months later
  • 46 years of age: developed worsening left shoulder and knee pain requiring multiple orthopedic visits for steroid injections
    • Developed loosening of hardware in left hip due to osteomalacia and continued to require frequent steroid therapy
    • Reported being compliant to conventional therapy
  • 47 years of age: under went knee replacement therapy evaluation
    • Unable to work and required disability benefits
    • Dependent on assistive walking devices
    • Developed ringing in ears and hearing loss
    • Referred to pain management; nerve pain medication added to regimen with little pain improvement
    • Laboratory findings (See Table)
  • 49 years of age: underwent left knee replacement; advised a right total knee replacement was needed as well
    • Insurance started denying coverage for calcitriol and phosphorus therapy on the basis that these medications are supplements/vitamins
    • Medication was continued with coverage through a grant
  • Patient reported compliance with conventional therapy; developed worsening back, neck, and hand pain
  • Could not afford dentures and had difficulty maintaining adequate nutrition
  • 3 months later: alternate therapeutic options were explored
The patient initiated oral phosphate and active vitamin D and was compliant. Symptoms of XLH continued to progress, leading to a search for alternative treatment options.
Test (reference rangea unit) Results 44 – years Results 47 – years
Serum phosphorus (2.4-5.7 mg/dL) 2.1 2.1
1,25 (OH)2 (20-80 ng/mL) 31 25
25(OH)D (25-80 ng/mL) 33 37
BSAP (6.5-20.1 mcg/L) 39.2 32.0
PTH (16-77 pg/mL) 95 48
Creatinine (0.72-1.25 mg/dL) 0.83 1.12
FGF23 (<180 RU/mL) 73 383

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; FGF23, fibroblast growth factor 23; PTH, parathyroid hormone.

 

aIndicates normal range, age, and sex matched. Note that normal range values may vary depending on reference dataset. These ranges were provided by the treating physician.

49-year-old male case study timeline
  • The patient was not accurately diagnosed with XLH until age 44
    • There is a spectrum of disease for XLH,1 and the patient’s symptoms were not previously attributed to XLH
  • Symptoms of XLH progressed throughout adulthood and had long-term impact. The patient:
    • Required surgeries and developed worsening pain
    • Required the use of assistive walking devices
    • Developed hearing loss
    • Needed dentures
  • Alternative therapeutic options were explored

*The information for this case study was provided courtesy of Dr. Kathryn 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. Results may vary. This case study does not claim to represent typical results.

Understand how you can manage the symptoms of XLH in your patients
Reference:

1. Ruppe MD. X-linked hypophosphatemia. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews®. University of Washington, Seattle; 1993-2022. Published February 9, 2012. Updated March 14, 2022. https://www.ncbi.nlm.nih.gov/books/NBK83985/