7077 A Rare Case Of Hypophosphatasia Presenting With Osteoporosis In A Young Female Patient- Diagnostic Delay In Hypophosphatasia

Abstract

Abstract Disclosure: R. Abdelmasih: None. I. Ali: None. Introduction: Hypophosphatasia is a rare hereditary cause of secondary osteoporosis that affects 1/100.000 individuals. The rate of osteoporosis due to hypophosphatasia is probably underestimated as it likely goes undiagnosed in heterogeneous or milder cases. We present a case of Hypophosphatasia that presented initially with osteoporosis and went misdiagnosed for years with intermittent treatment of Bisphosphonate, luckily with no atypical fractures that prompted different course of management for osteoporosis. Case Presentation: A 44-year-old female with a history of rheumatoid arthritis and osteoporosis diagnosed 7 years prior and treated with intermittent bisphosphonate which was discontinued due to side effects including muscle aches and bone pains, presented to our endocrinology clinic to establish care for osteoporosis. Patient denied prior fractures. She reported jaw pain that is being evaluated by otolaryngology and a dentist. Family history is negative. DEXA scan showed Z scores of -1.1, -1.8, and -2.2 of the lumbar spine, femoral neck, and total femur respectively. Laboratory workup showed consistently low alkaline phosphatase (ALP) 25, 20, <20 U/L (ref range 34-123), elevated Vitamin B6 of 167 nmol/L (ref range 20-125), normal parathormone, calcium, phosphate, Vit D, magnesium, and liver enzymes. Genetic testing was sent for Tissue non-specific alkaline phosphatase (TNALP). Hypophosphatasia was diagnosed based on clinical and laboratory findings, patient was started on Asfotase alfa. Clinical course is to be followed. Discussion: Hypophosphatasia is a rare hereditary disorder due to mutation of (TNALP). In normal induvial, TNALP breaks down pyrophosphate to phosphate. It also plays a role in transferring Vit B6 into the tissues. Hence, clinical presentation due to impaired calcium-phosphate hemostasis is broad including musculoskeletal pain, pseudofractues, dental abscess, and neurological symptoms (due to accumulation of Vit B6). The clinical picture varies depending on the heterogenicity of ALPL mutation. Genetic testing is not mandated to establish diagnosis, clinical presentation and laboratory testing including low ALP and elevated Vit B6 are sufficient. However, genetic testing and counseling are recommended for the patient’s sake and their family members. Antiresorptive bone therapy is contraindicated due to a further decrease of bone turnover with reported cases of increased risk of atypical femur fracture, Bone density is reported to improve with enzyme replacement therapy with bone-targeting recombinant alkaline phosphatase (Asfotase Alpha), if further treatment is needed, anabolic treatment is preferred. We present this case to shed light on such a rare disease to decrease rates of underdiagnosis or delayed diagnosis in young patients presenting with osteoporosis for prompt treatment and improved quality of life of these patients. Presentation: 6/2/2024