ESPE Abstracts

Background: Accurate diagnosis of disorders such as X-linked hypophosphatemia (XLH, OMIM 307800) and hypophosphatasia (HPP, OMIM 241510) critically depends on the use of appropriate pediatric reference ranges for serum phosphate and total alkaline phosphatase (ALP) values. However, many medical laboratories fail to implement these pediatric reference ranges, leading to missed diagnoses and delayed treatment. In Austria, as in many other countries, there are no legal mandates requiring the use of pediatric reference ranges or the disclosure of reference values utilized. This project seeks to evaluate the current diagnostic practices in Austria by distributing a blinded standard serum sample to all certified medical laboratories.

Aims: The primary aim of this study was to ascertain the proportion of medical laboratories in Austria that utilize appropriate pediatric reference ranges for serum phosphate and total ALP. The secondary aim was to enhance awareness among medical laboratories regarding the necessity of using accurate reference ranges for pediatric patients. Ultimately, the goal is to improve the diagnosis and treatment of disorders such as XLH and HPP, which can be overlooked without proper reference ranges.

Methods: blinded standard serum sample, labeled as originating from a 4-year-old girl, was sent to all accessible extramural medical laboratories in Austria. Parameters assessed included absolute values, stated reference ranges, and the interpretation of each laboratory for these two critical parameters.

Results: Out of 26 extramural laboratories, 22 analyzed the standardized sample with pathological values for the given patient’s age. Of these, 14 laboratories (64%) identified the serum phosphate levels as normal, while 8 laboratories (36%) reported the ALP levels as within the normal range. Only 4 laboratories provided reference values approximating the recommended CALIPER data for serum phosphate, and 9 laboratories did so for total ALP.

Data Availability: The findings reveal that the majority of extramural laboratories in Austria do not provide adequate pediatric reference values for critical serum parameters. Despite the accurate measurement of absolute values, the misinterpretation of these values due to the reliance on adult reference data is common. The absence of legal requirements and binding recommendations contributes to delays in diagnosis and treatment. Future efforts to reduce diagnostic delays must include the mandatory use of appropriate pediatric reference ranges to enable the accurate identification of conditions such as XLH and HPP.