BACKGROUND:
Vitamin D deficiency/insufficiency
(VDDI) is common in CKD patients and may be associated with abnormal
mineral metabolism. It is not clear whether the K/DOQI recommended doses
of ergocalciferol are adequate for correction of VDDI and
hyperparathyroidism.
METHODS:
Retrospective study of 88
patients with CKD Stages 1 - 5 and baseline 25-hydroxyvitamin D level
< 30 ng/ml (< 75 nmol/l). Patients treated with ergocalciferol as
recommended by K/DOQI guidelines. Only 53 patients had elevated baseline
PTH level for the CKD stage. Patients were excluded if they received
vitamin D preparations other than ergocalciferol or phosphate binders.
25-hydroxyvitamin D level, intact PTH level (iPTH), and other parameters
of mineral metabolism were measured at baseline and after completion of
ergocalciferol course.
RESULTS:
88 patients with CKD
were treated with ergocalciferol. Mean age 56.8 +/- 9.5 years and 41%
were males. The mean (+/- SD) GFR was 28.3 +/- 16.6 ml/min. At the end
of the 6-month period of ergocalciferol treatment, the mean
25-hydroxyvitamin D level increased from 15.1 +/- 5.8 to 23.3 +/- 11.8
ng/ml (37.75 +/- 14.5 to 58.25 +/- 29.5 nmol/l) (p < 0.001).
Treatment led to > or = 5 ng/ml (12.5 nmol/l) increases in
25-hydroxyvitamin D level in 54% of treated patients, and only 25%
achieved levels > or = 30 ng/ml (75 nmol/l). Mean iPTH level
decreased from 157.9 +/- 125.9 to 150.7 +/- 127.5 pg/ml (p = 0.5). Only
26% of patients had > or = 30% decrease in their iPTH level after
treatment with ergocalciferol.
CONCLUSIONS:
Current
K/DOQI guidelines are inadequate for correcting VDDI or secondary
hyperparathyroidism in CKD patients. Future studies should examine the
effects of higher or more frequent dosing of ergocalciferol on these
clinical endpoints.