The effect of vitamin K supplementation on circulating osteocalcin (bone Gla protein) and urinary calcium excretion.
OBJECTIVE
To determine whether vitamin K administration affects urinary calcium excretion in postmenopausal women.


METHODS
Before- and after-trials with a 2-week treatment period.


METHODS
Healthy postmenopausal women (55 to 75 years old) were recruited from the convents in and around Maastricht. Controls (25 to 40 years old) were healthy premenopausal volunteers.


METHODS
Daily administration of 1 mg of vitamin K for 2 weeks.


METHODS
Serum immunoreactive osteocalcin: hydroxylapatite binding (HAB) capacity of serum immunoreactive osteocalcin; excretion of calcium, hydroxyproline, and creatinine in the urine during the last 2 h of a 16-h fasting period.


RESULTS
In premenopausal women, no effect of vitamin K administration was seen. In the postmenopausal group, vitamin K induced increased serum immunoreactive osteocalcin concentration; normalization of the HAB capacity of serum immunoreactive osteocalcin (this marker was less than 50% that of the controls in the pretreatment samples); a decrease in urinary calcium excretion, notably in the "fast losers" of calcium; and a parallel decrease in urinary hydroxyproline excretion in the fast losers of calcium.


CONCLUSIONS
The serum immunoreactive osteocalcin level may vary with vitamin K status. This variance should be taken into consideration if osteocalcin is used as a marker for osteoblast activity. Vitamin K is one factor that may play a role in the loss of bone mass in postmenopausal osteoporosis.
Knapen
M H
MH
University of Limburg, Maastricht, The Netherlands.
Hamulyák
K
K
Vermeer
C
C
D000328:Adult; D000368:Aged; D002118:Calcium / Q000652:urine*; D003627:Data Interpretation, Statistical; D017886:Durapatite; D005260:Female; D006801:Humans; D006882:Hydroxyapatites; D006909:Hydroxyproline / Q000652:urine; D008593:Menopause / Q000097:blood / Q000652:urine; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood / Q000187:drug effects*; D011485:Protein Binding; D011863:Radioimmunoassay; D014812:Vitamin K / Q000494:pharmacology*
D006882:Hydroxyapatites; D015675:Osteocalcin; D014812:Vitamin K; D017886:Durapatite; D006909:Hydroxyproline; D002118:Calcium