| Introduction |
 Metabolic bone disease characterized by a generalized impairment of bone mineralization - Incidence
- estimated to be 1 in 100,000
- Pathophysiology
- low levels of alkaline phosphate result in decreased synthesis of inorganic phosphate necessary for bone matrix formation
- osteoid that forms in the hypertrophic zone of the growth plate fails to mineralize
- the zone of provisional calcification never forms and growth is inhibited
- Genetics
- inheritance pattern
- caused by a mutation in the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP)
Associated conditions
- orthopaedic manifestations
- similar to rickets
- bow legs
- short stature
- non-orthopaedic manifestations
- abnormal tooth formation
- loss of teeth
|
| Presentation |
- Clinical findings
- presentation similar to rickets
- abnormal dentition
|
| Imaging |
- Radiographs
- recommended
- AP and lateral of affected bone
- findings
- abnormal bone formation
- "deossification of bone" adjacent to growth plate
- physeal widening
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| Evaluation |
- Labs
- serum
- decreased serum alkaline phosphatase
- urine
- phosphoethanolamine in the urine diagnostic for hypophosphatasia
|
 |
| |
| Treatment |
- Nonoperative
- no approved therapies
- phosphate therapy under investigation but not utilized at this time
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Please Rate Educational Value!
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3.0
t-9083
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Average 3.0 of 8 Ratings
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Qbank (2 Questions)
TAG
(OBQ08.38)
Hypophosphatasia is associated with which of the following laboratory findings?
Review Topic
DISCUSSION:
Alkaline phosphatase is a marker of bone formation and is elevated when bone formation is increased. Hypophosphatasia is an autosomal recessive disorder caused by an inborn error in the production of alkaline phosphatase (tissue-nonspecific isoenzyme of alkaline phosphatase: TNSALP), leading to low alkaline phosphatase levels. Increased urinary phosphoethanolamine is also diagnostic.
REFERENCES:
1.
Einhorn TA, O'Keefe RJ. Buckwalter JA (EDS):Orthopedic Basic Science: Foundations of Clinical Practice, Third Edition. Rosemont, IL, American Academy of Orthopedic Surgeons, 2007, PP 415-426
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Please Rate Educational Value!
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2.0
q-424
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Average 2.0 of 17 Ratings
|
Level of Evidence 5 and Other Journal Articles (includes Case Reports, Expert Opinions,
Personal Observations, and Biomechanic Studies)
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Mornet E. Hypophosphatasia: the mutations in the tissue-nonspecific alkaline phosphatase gene. Hum Mutat. 2000;15(4):309-15.
PMID:10737975 (Link to Abstract)
Textbooks
- Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
- AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
- Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
- Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
- Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
- Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
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Ballock RT, O'Keefe RJ. Growth and development of the skeleton. In: Einhorn TA, O'Keefe RJ, Buckwalter JA, eds. Orthopaedic Basic Science: Foundations of Clinical Practice. 3rd ed. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2007:115-127.
Undefined
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Einhorn TA, O'Keefe RJ. Buckwalter JA (EDS):Orthopedic Basic Science: Foundations of Clinical Practice, Third Edition. Rosemont, IL, American Academy of Orthopedic Surgeons, 2007, PP 415-426
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