Bone Abstracts

Objective: The significance of low alkaline phosphatase (ALP) is often not recognised by clinicians. It is the hallmark of hypophosphatasia and this oversight leads to delays in diagnosis, inappropriate treatment and potentially harm. Using the standard that an abnormal result should be recognised by the clinician and the potential cause and need for further investigation documented in the medical records we conducted an audit of our practice at the Royal National Orthopaedic Hospital.

Methods: The biochemistry database was searched to identify patients aged less than 18 years with an abnormally low ALP. The medical records of those identified were reviewed to identify if the abnormal result was recognised, the relevant medical history and any further investigation.

Results: A search of 3031 ALP assays performed over 3 years identified 71 abnormal results and 28 patients with a persistently low ALP. None of the medical records showed any recognition of the abnormal result, consideration of its potential cause or plan for further investigation. Subsequently, one inpatient with acute disseminated encephalomyelitis with persistently low serum ALP was found to have a pathogenic heterozygous mutation in exon 5 of ALPL: c.346G>A, pAla116Thr.

Conclusions: Our findings correspond to existing reports (Saraff et al. J Pediatr. 2016;172:181–186.e1) and show that clinicians miss low ALP results, an omission that has and will continue to lead to undiagnosed cases of hypophosphatasia. This is crucial for the paediatric population as a specific treatment is licensed and can help prevent associated dental problems and reduce fracture risk. It is important that awareness amongst clinicians is raised and that ALP values are reported using an age adjusted lower limit of normal.

Disclosure: The authors declared no competing interests.