CV mortality in elderly unaffected by vitamin D, PTH
MedWire News: Serum levels of 25(0H)D, 1,25(OH)2D, and intact parathyroid hormone (iPTH) may not influence cardiovascular (CV) mortality risk in patients aged 60 years or older, US researchers report.
"Our null findings are compatible with results from randomized clinical trials of vitamin D supplementation to prevent CV outcomes," say Simerjot Jassal from the University of California in San Diego, and team.
As reported in The American Journal of Medicine, Jassal and colleagues measured the serum 25(0H)D, 1,25(OH)2D, and iPTH levels of 1073 community-dwelling patients aged over 60 years (mean 74 years). They found median serum levels of 42 ng/ml, 29 pg/ml, and 46 pg/ml, respectively.
Over a mean period of 6.4 years, 266 patients died, with 111 of these deaths being due to CV disease. Among these patients, 71 had an estimated glomerular filtration rate [eGFR] ≥60 ml/min/1.73 m2, while 40 had an eGFR <60 ml/min/1.73 m2.
Initial unadjusted findings showed that each standard deviation (SD) increase in serum log 1,25(OH)2D was associated with a 26% decrease in CV mortality risk. However, this decrease in CV mortality risk occurred only in patients with eGFR <60 ml/min/1.73 m2 (p<0.005).
Conversely, in all patients, each SD increase in serum log iPTH appeared to increase CV mortality risk by 25% (p<0.05).
However, after adjustment for multiple variables including age, gender, and systolic blood pressure, Jassal et al found no significant association between 25(0H)D, 1,25(OH)2D, and iPTH levels, and CV mortality risk, regardless of patient eGFR.
The researchers say that although they identified no protective effect of vitamin D on CV mortality, this may be because the CV protective effects of vitamin D occur only at serum levels higher than those of the patients in this trial.
They therefore conclude: "Additional prospective studies are needed to further investigate the levels of vitamin D and iPTH, if any, necessary to reduce CV mortality."
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By Lauretta Ihonor