summary Hypophosphatasia is a metabolic bone disease caused by a mutation in the isoenzyme of alkaline phosphatase that leads to low levels of alkaline phosphate and generalized impairment of bone mineralization. Patients present with clinical manifestations similar to rickets with bow legs, short stature, abnormal teeth, and increased susceptibility to fractures. Diagnosis is made with the presence of phosphoethanolamine in the urine. Treatment modalities are currently under investigation. Epidemiology Incidence estimated to be 1 in 100,000 Etiology 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 autosomal recessive 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 genu varum short stature abnormal dentition Imaging Radiographs recommended AP and lateral of affected bone findings abnormal bone formation "deossification of bone" adjacent to growth plate physeal widening 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
QUESTIONS 1 of 4 1 2 3 4 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ11.160) A decrease in alkaline phosphatase would most likely be manifest in which metabolic disorder? QID: 3583 Type & Select Correct Answer 1 Familial hypocalciuric hypercalcemia 16% (498/3182) 2 Hypophosphatasia 49% (1568/3182) 3 X-linked hypophosphatemia 17% (553/3182) 4 Secondary hyperparathyroidism 13% (415/3182) 5 Tertiary hyperparathyroidism 4% (116/3182) L 4 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (OBQ08.38) Hypophosphatasia is associated with which of the following laboratory findings? QID: 424 Type & Select Correct Answer 1 Hyperbilirubinemia 1% (14/1753) 2 Decreased urinary phosphoethanolamine 4% (76/1753) 3 Decreased urinary inorganic pyrophosphate 5% (80/1753) 4 Decreased serum phosphate 38% (674/1753) 5 Decreased serum alkaline phosphatase 51% (901/1753) L 4 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07PE.23) Figure 11 shows the radiograph of a 2-year-old child with marked genu varum and tibial bowing. Based on these findings, what is the best initial course of action? QID: 6083 FIGURES: A Type & Select Correct Answer 1 Obtain serum phosphorous, calcium, and alkaline phosphatase levels. 82% (511/625) 2 Obtain a scanogram to assess for limb-length discrepancy. 1% (4/625) 3 Perform bilateral valgus osteotomies to correct the deformities. 1% (9/625) 4 Measure the child for a varus prevention orthosis. 4% (27/625) 5 Educate the family about physiologic genu varum and conduct a follow-up examination in 6 months. 11% (67/625) L 2 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic
All Videos (0) Podcasts (1) Basic Science⎪Hypophosphatasia Basic Science - Hypophosphatasia Listen Now 5:34 min 8/13/2020 98 plays 0.0 (0)