Making the connection

Hypophosphatasia (HPP) in adults

Persistently low alkaline phosphatase (ALP) levels (<40 U/L)* can be the key to identifying HPP disease in some hard-to-diagnose patients.^1-5

*Limitations: An ALP level of below 40 U/L is not conclusive for diagnosis of HPP. Patient should be evaluated for other symptoms of HPP and differential diagnoses should be ruled out. Check with your lab for their appropriate age- and sex-adjusted reference range.

HPP is characterized by a range of signs and symptoms⁶

Neurological symptoms were seen in ~12% of adult patients with HPP

Observational, multinational, prospective Global HPP Registry study conducted in adults (n=148; ≥18 years) from January 2015 - September 2017.

Chart detailing the signs and symptoms of HPP

In HPP, low alkaline phosphatase activity leads to an accumulation of pyridoxal 5’-phosphate (PLP) in the systemic circulation resulting in a deficiency of vitamin B₆ in the central nervous system, which can cause seizures (which is most common in infants)⁷

Neurological symptoms may be present in adult patients with HPP⁸

A retrospective chart review studied the prevalence of common neurological symptoms associated with HPP^†

Chart detailing the neurological symptoms of HPP

^†Prevalence of neurological symptoms in adults with HPP (N=82) compared to the general US population.

Patient image is hypothetical.

Any clinical sign/symptom PLUS persistently low ALP is sufficient for an HPP diagnosis^7,9,10‡

<40 U/L ALP* is considered LOW in adults.^1-5

Learn how to determine if your patient’s ALP level is low.

^‡Limitations: An ALP level of 40 U/L is not conclusive for diagnosis of HPP. Patient should be evaluated for other symptoms of HPP, and differential diagnoses should be ruled out. Check with your lab for their appropriate age- and sex-adjusted reference range.

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QUICK QUESTION

Generally, below what threshold is an adult patient’s ALP considered low?

< 40 U/L* is considered low for adults

HPP should be considered if a review of historical patient charts shows persistently low ALP levels and they present with key signs and symptoms.^1-5,8-10

*Limitations: An ALP level of <40 U/L is not conclusive for diagnosis of HPP. Patient should be evaluated for other symptoms of HPP, and differential diagnoses should be ruled out. Check with your lab for their appropriate age- and sex-adjusted reference range.

References: 1. Adeli K, et al. Clin Chem. 2015;61(8):1049-1062. doi:10.1373/clinchem.2015.240515 2. Schumann G, et al. Clin Chem Lab Med. 2011;49(9):1439-1446. doi:10.1515/CCLM.2011.621 3. Quest Diagnostics. Alkaline phosphatase. Accessed August 31, 2021. https://testdirectory.questdiagnostics.com/test/test-detail/234/alkaline-phosphatase?cc=MASTER 4. Labcorp. Alkaline phosphatase. Accessed August 31, 2021. https://www.labcorp.com/tests/001107/alkaline-phosphatase 5. ARUP Laboratories. Alkaline phosphatase isoenzymes, serum or plasma. Accessed August 31, 2021. https://ltd.aruplab.com/Tests/Pub/0021020 6. Hӧgler W, et al. BMC Musculoskelet Disord. 2019;20(1):80. doi: 10.1186/s12891-019-2420-8 7. Rockman-Greenberg C. Pediatr Endocrinol Rev. 2013;10(suppl 2):380-388. 8. Colazo JM, et al. Osteoporos Int. 2019;30(2):469-480. doi: 10.1007/s00198-018-4691-6 9. Mornet E, et al. Hypophosphatasia. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews^®. University of Washington; 2007. Accessed November 4, 2021. https://www.ncbi.nlm.nih.gov/books/NBK1150/ 10. Whyte MP. Hypophosphatasia: nature’s window on alkaline phosphatase function in humans. In: Bilzikian JP, ed. Principles of Bone Biology. 3rd ed. Academic Press; 2008:1573-1598.