Characterization of vitamin D metabolism in active acromegaly in the setting of bolus (150,000 IU) cholecalciferol treatment.

PURPOSE: To reveal distinctive features of vitamin D metabolism in patients with active acromegaly compared to healthy individuals, particularly in the setting of cholecalciferol treatment. METHODS: The study group included 34 adults with active acromegaly, and the control group included 30 apparently healthy adults with similar age, sex, and BMI. All participants received a single dose (150,000 IU) of cholecalciferol aqueous solution orally. Laboratory assessments including serum vitamin D metabolites (25(OH)D3, 25(OH)D2, 1,25(OH)2D3, 3-epi-25(OH)D3 and 24,25(OH)2D3), free 25(OH)D, vitamin D-binding protein (DBP) and parathyroid hormone (PTH) as well as serum and urine biochemical parameters were performed before the intake and on Days 1, 3, and 7 after the administration. All data were analyzed with nonparametric statistics. RESULTS: Patients with acromegaly had tendency to lower baseline 25(OH)D3 levels (p = 0.05) and lower 25(OH)D3 levels (p < 0.05) during the follow-up. They were also characterized by PTH suppression (lower baseline PTH levels and lower prevalence of secondary hyperparathyroidism), altered production of main vitamin D metabolites (higher 1,25(OH)2D3 and lower 24,25(OH)2D3 levels with corresponding lower 25(ОН)D3/1,25(ОН)2D3 and higher 25(ОН)D3/24,25(ОН)2D3 ratios) as well as concordant biochemical features (higher levels of serum phosphorus and albumin-adjusted calcium levels) throughout the study (p < 0.05). The acromegaly group showed an increase in DBP levels after cholecalciferol intake as opposed to the control group (p < 0.05) and had lower increase in free 25(OH)D levels (p < 0.05). Δ25(OH)D3 was similar between the groups (p > 0.05), showed a negative correlation with the disease activity markers-both IGF-1 levels (r = -0.44, p < 0.05) and fasting GH levels (r = -0.56, p < 0.05)-and lacked correlation with BMI in the acromegaly group (p > 0.05). CONCLUSION: Patients with active acromegaly have dysregulated vitamin D metabolism characterized by higher 1,25(ОН)2D3, lower 24,25(ОН)2D3 and altered DBP production. The response to vitamin D supplementation in acromegaly patients might be influenced by hormonal excess. Obtained results require reproducibility check and further study to develop specific clinical recommendations. TRIAL REGISTRATION: NCT04844164 (release date: April 9, 2021; retrospectively registered).

[Vitamin D metabolism in hypercorticism and acromegaly].

Due to the high prevalence of low vitamin D levels in the overwhelming majority of regions of the world and discovery of extra-skeletal effects of vitamin D, the issue of maintaining adequate levels of vitamin D in the blood remains extremely relevant, especially in people with high risk of severe deficiency. To date, few studies have been performed on the features of vitamin D metabolism in disorders such as hypercorticism and acromegaly. However, vitamin D deficiency in such patients, according to available literature, may be more widespread and more pronounced than in general population. It is now recommended to use standard prophylactic and therapeutic doses of vitamin D for the treatment of these diseases, which may not satisfy the therapeutic goals specific to each disease. This review provides information on normal vitamin D metabolism, as well as literature data on the possible relationship and mutual influence between these endocrinopathies and vitamin D metabolism.