Working Diagnosis:
Hypophosphatasia

Treatment:
Additional history and labwork was done to rule out potential causes of low alkaline phosphatase including thyroid studies, vitamin D, and magnesium. All additional labs were within normal limits making hypophosphatasia the working diagnosis. The patient was referred to Endocrinology for further evaluation and to confirm the diagnosis. Rest was recommended while further evaluation was completed. She saw endocrinology who ordered genetic testing. Genetic testing of the ALPL gene found that the patient was heterozygous for an exon 3 ALP gene mutation resulting in a frame shift and confirming the diagnosis of hypophosphatasia. She was started on asfatase alfa.

Outcome:
Over the next several months she experienced an improvement in her symptoms and she was able to return to field hockey the following season. She also noticed improved energy, mood, and stamina on the medication. On review, she had no history of delayed walking, short stature, early loss of deciduous teeth, seizures, metatarsal stress fractures, chondrocalcinosis, pseudofractures, or known family history of hypophosphatasia.

Editor's Comments:
Hypophosphatasia is an inherited disorder disrupts mineralization of the bones and teeth. It is rare. Incidence is estimated at 1/100,000. Severe forms often are identified before birth or in infancy. Less severe forms can present in adulthood. It is often misdiagnosed. Common presentations can include joint pain and recurrent fractures in the feet and femurs due to osteomalcia. Genetic testing and treatment is available. Knowledge of this disease will help the sports medicine physician to keep wide differential diagnosis.

References:
NIH US National Library of Medicine. https://ghr.nlm.nih.gov/condition/hypophosphatasia#synonyms. Accessed 11/28/2018.
Hypophostasia.https://emedicine.medscape.com/article/945375-overview. Accessed 11/28/2018.

Return To The Case Studies List.