Low Vitamin D Levels in Patients Improved With Supplements

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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People with Cushing’s disease have a high risk of being deficient in vitamin D, but taking supplements can improve those levels, a new study indicates.

Results also showed that lower vitamin D levels are associated with higher levels of cortisol, a stress hormone that is elevated in Cushing’s.

The study, “Vitamin D Deficiency in Cushing’s Disease: Before and After Its Supplementation,” was published in Nutrients.

Cushing’s disease is caused by a tumor in the brain’s pituitary gland, which prompts the adrenal glands — hormone-producing glands that sit atop the kidneys — to produce and release excessive amounts of cortisol. High levels of cortisol cause the disease’s symptoms, which include weight gain, fat accumulation, and skin problems.

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Cortisol has a wide range of effects on the body and is known to indirectly regulate vitamin D levels. Too-low levels of it can interfere with normal immune function and increase the risk of bone fractures, among other health problems.

To learn more, a trio of scientists in Italy analyzed the levels of 25-hydroxyvitamin D, or 25(OH)D, an active metabolite of vitamin D, in the blood of 50 Cushing’s patients. Most of them (86%) were women, and they had a mean age of 50.9. A group of 48 people without Cushing’s disease, of similar age and gender, served as controls.

The Cushing’s patients had a greater frequency of several other health conditions, including high blood pressure, diabetes, and muscle disease, compared with controls. They also had significantly higher cholesterol and blood sugar levels.

Mean 25(OH)D levels in Cushing’s patients were significantly lower than in controls, specifically 16.7 nanograms per milliliter (ng/mL) to 28.7 ng/mL.

More than half (52%) of the patients had vitamin D levels that were low enough to constitute a deficiency, whereas fewer than one in 10 (8.4%) of the controls was considered deficient. In fact, most controls (70.8%) had levels high enough to be considered “sufficient.” Only 20% of Cushing’s patients had sufficient levels.

Of note, vitamin D was considered deficient when 25(OH)D levels were lower than 20 ng/mL, insufficient when levels ranged between 20–30 ng/mL, and sufficient at values equal or greater than 30 ng/mL.

Statistical analyses showed an inverse correlation between 25(OH)D levels and mean urinary free cortisol (mUFC) levels. In other words, patients with higher cortisol levels in their urine tended to have lower levels of vitamin D in their blood, and vice versa.

Analyses also showed that measuring cortisol levels could help predict vitamin D deficiency. At a cutoff of mUFC higher than 240 nanomole per 24 hours (nmol/24 h), the specificity of predicting deficiency from cortisol levels was 100%, meaning that all patients who did not have such high levels of cortisol did not have a deficiency. The sensitivity, or true-positive rate, for diagnosing vitamin D deficiency based on cortisol levels was 56.9%.

“We found that higher values of mUFC than 240 nmol/24 h are predictive of 25(OH)D deficiency,” the researchers wrote.

As part of the study’s secondary objective, Cushing’s patients were given vitamin D supplements (150,000 international units) and then re-analyzed six weeks after treatment.

Taking supplements significantly increased 25(OH)D and blood calcium levels and improved insulin sensitivity, while lowering total cholesterol levels, results showed.

Taking supplements “has a positive impact on insulin sensitivity and lipids [fatty molecules] and therefore should be considered part of the treatment of patients with [Cushing’s disease] at diagnosis,” the researchers concluded.

They emphasized that further research is needed to better understand the potential benefits and risks of using vitamin D supplements to help manage Cushing’s.