Abnormal bone turnover in individuals with low serum alkaline phosphatase

Area of Science:

• Endocrinology
• Metabolic Bone Disease
• Biochemistry

Background:

• Hypophosphatasia (HPP) presents with a wide clinical spectrum, including mild adult forms discovered incidentally through low serum alkaline phosphatase (ALP).
• The skeletal implications of persistently low ALP in adults without overt HPP manifestations remain unclear, particularly regarding bone remodeling and mass.

Purpose of the Study:

• To investigate the skeletal phenotype in adults with persistently low serum ALP.
• To analyze bone mineral density (BMD), bone microarchitecture (trabecular bone score, TBS), and bone turnover markers (P1NP, ß-crosslaps).

Main Methods:

• Study included 42 adults with persistently low serum ALP.
• Evaluated bone mineral density (BMD), trabecular bone score (TBS), and serum markers of bone turnover (P1NP and ß-crosslaps).
• Compared findings with a control group.

Main Results:

• Individuals with low ALP exhibited significantly lower levels of P1NP and ß-crosslaps compared to controls, indicating reduced bone turnover.
• No significant differences were observed in BMD, bone mineral content, or TBS between the low ALP group and controls.
• These findings suggest a generalized reduction in bone remodeling in individuals with hypophosphatasemia.

Conclusions:

• Adults with persistently low serum ALP have reduced bone turnover, irrespective of overt HPP symptoms or normal BMD.
• The data support avoiding antiresorptive agents, such as bisphosphonates, in individuals with hypophosphatasemia due to altered bone remodeling.