Short and long-term variations in serum calciotropic hormones after a single very large dose of ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) in the elderly

CONTEXT

In humans, few studies have compared the potencies of ergocalciferol and cholecalciferol in improving and maintaining vitamin D status.

OBJECTIVE

Our objective was to evaluate the effects of a single very large dose of both calciferols on serum changes of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D], ionized calcium, and parathyroid hormone (PTH) at baseline, and at 3, 7, 30, and 60 d.

DESIGN

This was a prospective randomized intervention study.

SETTING

The study was performed in a nursing home residence.

PARTICIPANTS

A total of 32 elderly female patients (age range 66-97 yr), with vitamin D deficiency was included in the study.

INTERVENTION

Participants were randomized into four groups of eight to receive a single dose of 300,000 IU ergocalciferol or cholecalciferol by oral (os) or im route.

RESULTS

25(OH)D levels sharply increased at d 3 only when vitamins were given os. The 30-d basal difference in serum 25(OH)D was significantly greater after cholecalciferol os administration (47.8 +/- 7.3 ng/ml) compared with other forms (D(3) im: 15.9 +/- 11.3; D(2) os: 17.3 +/- 4.7; D(2) im: 5 +/- 4.4; all P < 0.001). The area under the curve (AUC) of the serum 25(OH)D against time (AUC(60)) was: D(3) os, 3193 +/- 759 ng x d/ml vs. D(2) os, 1820 +/- 512, P < 0.001; and D(3) im, 1361 +/- 492 vs. D(2) im, 728 +/- 195, P < 0.01. 25(OH)D significantly influences PTH levels at 3 (P < 0.03), 7 (P < 0.01), 30 (P < 0.01), and 60 d (P < 0.05). At 60 d, the form of vitamin (cholecalciferol) significantly lowers PTH levels (P = 0.037).

CONCLUSIONS

Cholecalciferol is almost twice as potent as ergocalciferol in increasing serum 25(OH)D, when administered either by mouth or im. 25(OH)D plays a role in modulating serum PTH.