Absence of recognition of low alkaline phosphatase level in a tertiary care hospital

Low serum total alkaline phosphatase level (ALP), the hallmark for hypophosphatasia (HPP), must be recognized to provide appropriate care of the patients and to avoid antiresorptive treatment. The prevalence of persistent low ALP in a clinical setting is 0.13% and the recognition is very low (3%).

A low serum total alkaline phosphatase level is the hallmark for the diagnosis of hypophosphatasia. Although very rare, HPP must be recognized to provide appropriate treatment of non-union fractures and to avoid potentially harmful drugs, such as antiresorptive treatments. The aim of this study was to assess the recognition of persistent low ALP in a tertiary care hospital.

Between the 1st of January and the 31st of December 2013, 48,755 patients had ALP assessment in the Biochemistry Department of our hospital. Sixty-eight patients had all serum ALP values persistently below 40 IU/l. Among them, six had potential causes of secondary hypophosphatasia. We consulted the summary discharges of the 62 patients in order to check for the notation of low ALP. Patients from the departments of rheumatology and internal medicine were contacted to fulfill a questionnaire about clinical manifestations potentially related to HPP.

0.13% of hospitalized patients had persistently low value. They were 46.5 ± 17.7 years old, and 73% were females. The low ALP value was notified in the discharge summary for two patients (3%), without any comment. Twenty-four patients (46 + /-16 years old) were contacted. Eight patients had fractures; two had a diagnosis of rickets in the childhood; two had symptomatic chondrocalcinosis. Nine had dental abnormalities. Three were receiving a bisphosphonate; two of them had a fracture while being treated with bisphosphonate.

Our study shows that low ALP is not recognized in a clinical setting in adults hospitalized in a tertiary care hospital.