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Notes:
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Background: Vascular calcification (VC) contributes to high mortality rates in chronic kidney disease (CKD). High
serum phosphate and FGF23 levels and impaired phosphaturic response to FGF23 may affect VC. Therefore, their
relative contribution to abdominal aortic calcification (AAC) was examined in patients CKD stages 3–4.
Methods: Potential risk factors for AAC, measured by the Kauppila Index (KI), were studied in 178 patients.
Results: In multivariate linear analysis, AAC associated positively with age, male gender, CKD-stage, presence of
carotid plaques (CP) and also with FGF23, but negatively with fractional excretion of phosphate (FEP). Intriguingly,
FEP increased with similar slopes with elevations in PTH, with reductions in GFR, and also with elevations in FGF23
but the latter only in patients with none (KI = 0) or mild (KI = 1-5) AAC. Lack of a FEP-FGF23 correlation in patients
with severe AAC (KI > 5) suggested a role for an impaired phosphaturic response to FGF23 but not to PTH in AAC.
Logistic and zero-inflated analysis confirmed the independent association of age, CKD stage, male gender and CP
with AAC, and also identified a threshold FEP/FGF23 ratio of 1/3.9, below which the chances for a patient of
presenting severe AAC increased by 3-fold. Accordingly, KI remained unchanged as FEP/FGF23 ratios decreased
from 1/1 to 1/3.9 but markedly increased in parallel with further reductions in FEP/FGF23 < 1/3.9.
Conclusions: In CKD 3–4, an impaired phosphaturic response to FGF23 with FEP/FGF23 < 1/3.9 associates with
severe AAC independently of age, gender or CP. |
