Objective Low serum alkaline phosphatase (ALP) is the hallmark of hypophosphatasia and a sign of a number of other conditions, such as zinc deficiency. There is evidence that it is often unrecognised by clinicians leading to delay in diagnosis, inappropriate treatment and, in some cases, harm. We conducted an audit of our practice looking at the recognition of abnormally low serum ALP results by clinicians. We used the standard that the clinician should recognise the abnormal result and that a consideration of the potential cause and need for further investigation should be documented in the patient’s notes.

Methods Using the age specific reference ranges produced by Pathology Harmony we searched the biochemistry database to find all patients aged under 18 years with an abnormally low serum ALP. We then reviewed the notes of these patients to identify if the abnormal result was recognised, the medical situation in which the ALP was measured and what further investigation was done.

Results Searching 3,031 samples we identified 19 patients with an abnormally low serum ALP. We did not find documentation to show recognition of the abnormal result in any of the patients’ notes. We found no evidence that for any of the patients the potential cause of the abnormal result was considered.

Conclusions To the best of our knowledge, this is the first audit of the recognition of abnormally low serum ALP levels in children. The results correspond to existing studies and show that clinicians may frequently miss abnormally low levels. This will lead to undiagnosed cases of hypophosphatasia. This is a crucial omission for the paediatric population as a specific treatment is licensed and available. We propose two necessary changes. Firstly, that the awareness of the potential significance of low ALP values is increased and secondly, it is of critical importance that ALP values are reported using an age adjusted lower limit of normal such as those produced by Pathology Harmony.