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Nursing Guide to Hypophosphatasia: Nursing Diagnosis, Interventions, & Care Plans

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Updated On 8 Minute Read

Hypophosphatasia (HPP) is a rare, inherited metabolic disorder noted by defective bone and tooth mineralization due to low activity of tissue-nonspecific alkaline phosphatase (TNSALP). The disease manifests with a broad clinical spectrum ranging from perinatal lethality to mild dental anomalies in adulthood.  

HPP results in the accumulation of substrates like inorganic pyrophosphate (PPi), which impairs hydroxyapatite crystal formation essential for bone and dental mineralization.  

Nursing care for patients with HPP involves supporting diagnostic work-up, managing symptoms, administering enzyme replacement therapy when prescribed, and educating patients and families about the chronic nature of the disease. 

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Etiology and epidemiology 

HPP occurs from mutations in the ALPL gene, which encodes the tissue-nonspecific alkaline phosphatase (TNSALP) enzyme. TNSALP is critical for bone mineralization because it breaks down substrates like inorganic pyrophosphate (PPi), phosphoethanolamine (PEA), and pyridoxal 5′-phosphate (PLP).  

Mutations in ALPL lead to reduced or absent TNSALP activity, resulting in the accumulation of these substrates. Elevated levels of PPi inhibit hydroxyapatite formation, compromising bone strength and leading to characteristic skeletal and dental manifestations. 

Inheritance 

  • Autosomal recessive: This is responsible for more severe phenotypes, including perinatal and infantile HPP. Both parents are typically asymptomatic carriers.
  • Autosomal dominant: This is associated with milder phenotypes such as childhood-onset, adult-onset, and odonto-hypophosphatasia. The inheritance pattern may present with variable expressivity and incomplete penetrance within families. 

Genetic counseling is essential for families, especially when planning future pregnancies or interpreting carrier status. 

Epidemiology 

  • The estimated incidence of severe forms (perinatal and infantile) is approximately 1 in 100,000 live births, although prevalence varies by population.
  • Milder forms such as odonto-hypophosphatasia and adult-onset HPP may be significantly underdiagnosed due to non-specific symptoms like early tooth loss or musculoskeletal pain.
  • HPP affects males and females equally and occurs in all racial and ethnic groups.
  • Advancements in genetic testing and increased clinical awareness have led to more frequent identification of milder forms. 

ICD-10 code 

  • E83.39 — Other disorders of phosphorus metabolism and phosphatases (includes HPP) 

Assessment 

Assessment is based on a combination of clinical assessment, biochemical testing, radiographic findings, and molecular genetic analysis. Early and accurate diagnosis helps initiate appropriate treatment and prevent complications, particularly in the more severe pediatric forms. 

Clinical features 

  • Skeletal abnormalities: Rickets-like changes including bowed legs, delayed closure of fontanelles, widened growth plates, and increased fracture risk due to poor bone mineralization. Chronic pain and pseudofractures may also occur.
  • Dental anomalies: Early loss of primary teeth with intact roots, often before age five, due to defective cementum formation. Adults may have enamel hypoplasia or persistent periodontal issues.
  • Failure to thrive: In infancy, poor feeding, irritability, and inadequate weight gain may reflect underlying metabolic bone disease.
  • Respiratory compromise: Particularly in perinatal or severe infantile cases, hypoplastic chest and muscle weakness can lead to ventilatory insufficiency and increased mortality risk.
  • Neuromuscular symptoms: Generalized hypotonia, proximal muscle weakness, gait disturbances, and developmental motor delays.
  • Adult manifestations: Chronic musculoskeletal pain, stress fractures, early-onset osteoarthritis, and calcific periarthritis. Chondrocalcinosis may be observed in older individuals. 

Laboratory findings 

  • Low serum alkaline phosphatase (ALP): This is a hallmark biochemical feature and must be interpreted in the context of age- and sex-specific reference ranges.
  • Elevated pyridoxal 5′-phosphate (PLP): This is the active form of vitamin B6, often elevated due to impaired PLP dephosphorylation. This finding may support the diagnosis, particularly when ALP is low.
  • Increased levels of inorganic pyrophosphate (PPi): Detected in blood or urine, this contributes to defective bone mineralization by inhibiting hydroxyapatite formation.
  • Genetic testing: This confirms the diagnosis by identifying pathogenic variants in the ALPL gene. Biallelic mutations typically correlate with more severe phenotypes. 

Imaging 

  • X-rays: This may reveal metaphyseal flaring, osteopenia, rachitic rosary, and poorly mineralized bones in children. Fractures may be transverse, stress-related, or involve pseudofracture patterns.
  • Skeletal surveys: This is used to evaluate the extent of skeletal involvement in infants and young children. Serial imaging may be necessary to monitor progression or response to therapy.
  • CT or MRI (selected cases): This may assist in assessing spinal abnormalities, craniosynostosis, or complications involving the chest wall or long bones. 

Management 

Treatment of HPP varies depending on disease severity and presentation. Management requires a multidisciplinary approach, including pharmacologic therapy, supportive interventions, and long-term monitoring tailored to the patient’s age and clinical phenotype. 

Pharmacologic therapy 

  • Asfotase alfa (Strensiq): A recombinant TNSALP enzyme administered via subcutaneous injection, it replaces deficient alkaline phosphatase activity and improves survival, bone mineralization, and physical function in patients with perinatal, infantile, and juvenile-onset HPP. Dosing is weight-based and requires regular clinical follow-up to monitor for injection site reactions, ectopic calcification, and hypersensitivity events.
  • Pain management: Acetaminophen or other non-NSAID analgesics are preferred due to bleeding risks in some patients. For older children and adults with chronic pain, referral to pain management may be needed for individualized plans that incorporate physical, pharmacological, and psychosocial strategies. 

Supportive care

  • Nutritional support: For infants and young children with feeding challenges, a dietitian can help ensure adequate caloric intake to support growth. Gastrostomy feeding may be indicated in severe cases of failure to thrive.
  • Physical and occupational therapy: These therapies improve gross and fine motor skills, muscle strength, endurance, and functional mobility. Adaptive equipment such as walkers, orthotics, or wheelchairs may enhance independence.
  • Dental care: Regular dental evaluations and oral hygiene education are crucial to manage premature tooth loss and maintain oral health. Collaboration with pediatric dentists is essential.
  • Respiratory support: In patients with thoracic deformities or muscle weakness, respiratory therapy may involve oxygen, noninvasive ventilation (e.g., CPAP), or tracheostomy in severe cases. Close monitoring of respiratory status is especially important during acute illnesses. 

Monitoring 

  • Growth and development: Track height, weight, and head circumference using syndrome-specific charts; assess achievement of developmental milestones and intervene early when delays are identified.
  • Respiratory function: Monitor respiratory rate, work of breathing, oxygen saturation, and tolerance for activity, particularly in infants and toddlers at risk for thoracic insufficiency.
  • Biochemical markers: Regularly evaluate serum ALP, PLP (vitamin B6), and calcium/phosphate levels to assess treatment response and metabolic status.
  • Imaging: Periodic radiographs of the long bones and chest may help evaluate bone mineralization, fracture healing, and progression of skeletal abnormalities. In select cases, DEXA scans may be used to assess bone density over time. 

Nursing care plan 

Nursing care for individuals with HPP is integral to managing the disease’s chronic and multisystemic manifestations. Given the variable presentation, from perinatal respiratory compromise to adult musculoskeletal pain, nurses must be skilled in comprehensive assessment, symptom monitoring, medication administration, and caregiver education.  

A proactive and individualized approach is a must to support developmental progress, manage physical limitations, and empower families navigating this rare and complex disorder. 

Nursing considerations 

  • Understand the progressive, variable nature of HPP across life stages and how symptom presentation may shift with age.
  • Administer enzyme replacement therapy per protocol and monitor for injection site reactions, hypersensitivity, or other adverse effects.
  • Provide emotional support and coordinate care across multiple specialties, including endocrinology, genetics, pulmonology, dentistry, and nutrition. Ensure families have access to psychosocial services and community resources. 

Assessment 

  • Monitor weight, height, and developmental milestones using syndrome-specific growth charts.
  • Evaluate musculoskeletal status, including pain, range of motion, joint alignment, muscle tone, and postural stability.
  • Observe respiratory rate, effort, breath sounds, and signs of fatigue or cyanosis, especially in infants and during acute illness.
  • Assess oral health and premature tooth loss, looking for gingival inflammation, feeding issues, and enamel defects. 

Nursing diagnosis/risk for 

  • Risk for impaired physical mobility related to bone pain, joint abnormalities, and skeletal fragility
  • Risk for delayed growth and development related to chronic illness, nutritional challenges, and neuromuscular limitations
  • Risk for ineffective breathing pattern in severe pediatric cases due to thoracic deformities, muscle weakness, or respiratory infection
  • Risk for caregiver role strain related to long-term care demands, complex medical regimens, and emotional burden 

Interventions 

  • Facilitate multidisciplinary referrals and coordinate care team communication.
  • Support caregivers in medication administration, safe handling of enzyme replacement therapy, and recognition of side effects.
  • Encourage adaptive strategies for safe ambulation and transfers, such as assistive devices, orthotics, or home modifications.
  • Promote energy conservation and balanced activity planning by structuring rest periods and alternating strenuous tasks with lighter activities. 

Expected outcomes 

  • Patient exhibits improved physical mobility and pain control.
  • Growth and development are supported and monitored effectively.
  • Caregivers verbalize understanding of disease, medication, and home care management.
  • Patient maintains airway and respiratory status within safe parameters. 

Individual/caregiver education 

  • Overview of genetic cause and inheritance patterns, including the implications for future family planning and the availability of genetic counseling
  • Importance of medication adherence and enzyme therapy scheduling, including strategies for managing missed doses, side effects, and treatment expectations
  • Recognizing signs of respiratory distress, bone pain, or fatigue, and knowing when to contact the healthcare provider
  • Techniques for safe lifting, mobility support, and dental care, including instruction on use of adaptive equipment and toothbrushing methods that minimize trauma
  • Encouragement to access support groups, peer networks, and genetic counseling services to reduce isolation and promote psychosocial well-being 

FAQs

Resources 

References 

Dasha Johnson, RN

Dasha Johnson, MSN, RN

Dasha Johnson, MSN, RN, began her career with the Absentee Shawnee Tribal Health System (ASTHS) in July 2021 as a Public Health RN. She was later promoted to Director of Nursing and now serves as Director of Quality. A Registered Nurse for 13 years, Dasha began at the Oklahoma City VA Emergency Department and later worked in the PACU and Community Care departments before joining ASTHS. At 18, she enlisted in the Oklahoma Air National Guard as an Aeromedical Evacuation Technician, deploying in support of Operations Iraqi and Enduring Freedom. She also provided aid during Hurricanes Katrina and Harvey. Commissioned as a Clinical Nurse in 2016, she retired as a Captain in 2023 after 21 years of service.