Heterogeneity in serum 25-hydroxy-vitamin D response to cholecalciferol in elderly women with secondary hyperparathyroidism and vitamin D deficiency.
OBJECTIVE
To compare the effects on parathyroid hormone (PTH) and 25-hydroxy-vitamin D (25(OH)D) of two dosing regimens of cholecalciferol in women with secondary hyperparathyroidism (sHPTH) and hypovitaminosis D and to investigate variables affecting 25(OH)D response to cholecalciferol.


METHODS
Randomized-controlled trial with 6-month follow-up.


METHODS
Two osteoporosis centers in northern Italy.


METHODS
Sixty community-dwelling women aged 65 and older with sHPTH and hypovitaminosis D, creatinine clearance greater than 65 mL/min and without diseases or drugs known to influence bone and vitamin D metabolism.


METHODS
Cholecalciferol 300,000 IU every 3 months, once at baseline and once at 3 months (intermittent D(3) group) or cholecalciferol 1,000 IU/day (daily D(3) group).


METHODS
Serum PTH, 25(OH)D, calcium, bone-specific alkaline phosphatase, β-C-terminal telopeptide of type I collagen, phosphate, 24-hour urinary calcium excretion.


RESULTS
The two groups had similar baseline characteristics. All participants had vitamin D deficiency [25(OH)D<20 ng/mL)], and 36 subjects (60%) had severe deficiency (<10 ng/mL), with no difference between the groups (severe deficiency: intermittent D(3) group, n=18; daily D(3) group, n=18). After 3 and 6 months, both groups had a significant increase in 25(OH)D and a reduction in PTH. Mean absolute increase ± standard deviation of 25(OH)D at 6 months was higher in the intermittent D(3) group (22.7±11.8 ng/mL) than in the daily D(3) group (13.7±6.7 ng/mL, P<.001), with a higher proportion of participants in the intermittent D(3) group reaching desirable serum concentration of 25(OH)D≥30 ng/mL (55% in the intermittent D(3) group vs 20% in the daily D(3) group, P<.001). Mean percentage decrease of PTH in the two groups was comparable, and at 6 months, a similar proportion of participants reached normal PTH values. 25(OH)D response to cholecalciferol showed a wide variability. In a logistic regression analysis, body mass index and type of treatment appeared to be significantly associated with normalization of 25(OH)D values.


CONCLUSIONS
Cholecalciferol 300,000 IU every 3 months was more effective than 1,000 IU daily in correcting vitamin D deficiency, although the two groups achieved similar effects on PTH at 6 months. Only 55% of the higher-dose intermittent group reached desirable concentrations of 25(OH)D, suggesting that yet-higher doses will be required for adequate vitamin D repletion.
Giusti
Andrea
A
Department of Gerontology and Musculoskeletal Sciences, Galliera Hospital, Genoa, Italy. andrea.giusti@galliera.it
Barone
Antonella
A
Pioli
Giulio
G
Girasole
Giuseppe
G
Razzano
Monica
M
Pizzonia
Monica
M
Pedrazzoni
Mario
M
Palummeri
Ernesto
E
Bianchi
Gerolamo
G
D000368:Aged; D000469:Alkaline Phosphatase / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000097:blood / Q000652:urine; D002762:Cholecalciferol / Q000008:administration & dosage*; D024042:Collagen Type I / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000188:drug therapy*; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000378:metabolism; D010710:Phosphates / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000188:drug therapy*; D014815:Vitamins / Q000008:administration & dosage*
D015415:Biomarkers; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010455:Peptides; D010710:Phosphates; D014815:Vitamins; C052929:collagen type I trimeric cross-linked peptide; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase; D002118:Calcium