Alkaline Phosphatase and Parathyroid Hormone Levels: International Variation and Associations With Clinical Outcomes in the DOPPS.
In nearly 29,000 haemodialysis patients across nine countries, total alkaline phosphatase predicted death and fractures more consistently than parathyroid hormone, suggesting it may be a more useful marker for managing bone and mineral disorder.
Background
Secondary hyperparathyroidism increases fracture and cardiovascular risk in haemodialysis patients, but the relationship between PTH and outcomes has been inconsistent, possibly because bone responsiveness to PTH varies between patients. KDIGO suggests monitoring total alkaline phosphatase (ALP), but the relative roles of ALP and PTH are unclear.
Study design
Analysis of 28,888 haemodialysis patients across 9 countries in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 3-7 (2005-2021). Normalised ALP and PTH (values divided by each facility's upper normal limit) at enrolment were related to all-cause and cardiovascular mortality and to fracture using adjusted Cox models.
Key findings
Normalised PTH had a J-shaped association with all-cause and cardiovascular mortality and only a weak linear association with fracture, while normalised ALP showed a strong association with all outcomes. Higher ALP (independent of PTH) was associated with Black race, longer dialysis vintage, diabetes, hypocalcaemia, hypophosphataemia, elevated CRP and cinacalcet use.
Clinical implications
Total ALP is a more robust marker of adverse outcomes than PTH in haemodialysis patients. Because PTH responsiveness is affected by race, primary renal disease, comorbidity and therapy, assessing target-organ response (ALP) rather than PTH alone may improve CKD-MBD management.
Category
Research
Source
Kidney International Reports
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