Vitamin D status and secondary hyperparathyroidism: the importance of 25-hydroxyvitamin D cut-off levels.
BACKGROUND
Serum 25-hydroxyvitamin D is the best indicator of vitamin D status. However, some controversy remains regarding "normal" and "abnormal" values. This study's aim was to assess vitamin D status and prevalence of secondary hyperparathyroidism.


METHODS
A random sample of 326 subjects (164 women and 162 men, aged 68 +/- 9; range, 54 to 89) participating in the European Vertebral Osteoporosis Study (EVOS) was used to assess vitamin D status and secondary hyperparathyroidism. Only those subjects who had never received any kind of treatment for osteoporosis were included in this analysis.


RESULTS
Serum 25-hydroxyvitamin D levels were "deficient" (<10 ng/mL) in 27% of subjects, "borderline" (10-18 ng/mL) in 40% of subjects, and "normal" (>18 ng/mL) in 33% of subjects. The prevalence of secondary hyperparathyroidism (PTH>65 pg/mL) according to 25-hydroxyvitamin D levels was 33% (<10 ng/mL), 16% (10-18 ng/mL), and 12% (>18 ng/mL), respectively. There were no cases of secondary hyperparathyroidism with 25-hydroxyvitamin D levels>40 ng/mL. The independent predictors for PTH were 25-hydroxyvitamin D and serum creatinine in both sexes, but age was a predictor only in men.


CONCLUSIONS
These remarkable findings demonstrate the importance of maintaining higher 25-hydroxyvitamin D levels to avoid stimulation of the parathyroid gland.
Gómez-Alonso
Carlos
C
Bone and Mineral Research Unit, Instituto Reina Sofía de Investigación, Hospital Central de Asturias, Universidad de Oviedo, Spain. cgomez@hca.es
Naves-Díaz
Manuel L
ML
Fernández-Martín
Jose L
JL
Díaz-López
Jose B
JB
Fernández-Coto
Maria T
MT
Cannata-Andía
Jorge B
JB
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D013030:Spain / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000453:epidemiology
D014807:Vitamin D; C104450:25-hydroxyvitamin D