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Eur J Endocrinol. 2013 Oct 21;169(6):767-72. doi: 10.1530/EJE-13-0510. Print 2013 Dec.

Vitamin D increases circulating IGF1 in adults: potential implication for the treatment of GH deficiency.

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1
Internal Medicine Unit, Department of Internal Medicine, Centre of Excellence for Biomedical Research, IRCCS-AOU San Martino-IST, University of Genova, Viale Benedetto XV, 6, 16132 Genova, Italy.

Abstract

OBJECTIVES:

Previous studies suggested that vitamin D modulates circulating IGF1. We investigated this effect in adults and its clinical relevance in the management of GH deficiency (GHD).

DESIGN AND METHODS:

IGF1 levels were prospectively measured before and after 12 weeks of treatment with oral vitamin D3 (5000 or 7000 IU/week) vs no intervention in 39 subjects 61.9±7.9 years old. The frequency of IGF1 values ≥50th age- and sex-specific percentile in relation to vitamin D status, as determined by the concentration of 25-hydroxyvitamin D (25(OH)D), was retrospectively assessed in 69 GHD patients (57.4±16.6 years) on stable hormone replacement and with 25(OH)D and IGF1 concurrently measured.

RESULTS:

Treatment with 5000 and 7000 IU vitamin D3/week significantly raised 25(OH)D by 12.7±8.4 and 13.1±6.5 ng/ml respectively (both P<0.001 vs baseline). In the 7000 IU group, IGF1 levels also significantly increased by 31.3±36.7 ng/ml (P=0.01). Neither 25(OH)D nor IGF1 significantly varied in controls. IGF1 was ≥50th percentile more frequently in GHD patients with 25(OH)D levels ≥15 than <15 ng/ml (65.9 vs 40.0%, P<0.05). Logistic regression with adjustment for recombinant human GH (rhGH) dose, vitamin D supplements, gender, use of thyroid hormones, corticosteroids or estrogen/testosterone, and season revealed a significant positive association between ≥15 ng/ml 25(OH)D and IGF1 ≥50th percentile (OR 4.4, 95% CI 1.0-18.8, P<0.05). A significant negative correlation between 25(OH)D concentrations and rhGH dose was found after correcting for age and IGF1 (β -0.042, P<0.01), but not after further adjusting for sex, thyroid, adrenal or gonadal replacement, and season (β -0.037, P=0.06).

CONCLUSIONS:

Vitamin D increases circulating IGF1 in adults. As a result, a better vitamin D status may ease the achievement of normal IGF1 values in GHD.

PMID:
24005315
DOI:
10.1530/EJE-13-0510
[Indexed for MEDLINE]
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