Vitamin D deficiency occurs frequently in COPD and correlates with severity

Vitamin D is a steroid hormone and a component of a complex endocrine pathway sometimes called 'vitamin D endocrine system' (Medscape, 2012).  1 in 4 individuals will develop COPD during their lifetime (Lancet, 2011).

Serum 25-hydroxyvitamin D (25-OHD) levels were measured in 414 (ex)-smokers older than 50 years and the link between vitamin D status and presence of COPD was assessed. The rs7041 and rs4588 variants in the vitamin D-binding gene (GC) were genotyped and their effects on 25-OHD levels were tested.

In patients with COPD, 25-OHD levels correlated significantly with forced expiratory volume in 1 s (FEV1).

Compared with 31% of the smokers with normal lung function, as many as 60% and 77% of patients with GOLD (Global Initiative for Obstructive Lung Disease) stage 3 and 4 exhibited deficient 25-OHD levels lower than 20 ng/ml.

25-OHD levels were reduced by 25% in homozygous carriers of the rs7041 at-risk allele.

76% and 100% of patients with GOLD stage 3 and 4 homozygous for the rs7041 allele exhibited 25-OHD levels lower than 20 ng/ml.

Vitamin D deficiency occurs frequently in COPD and correlates with severity of COPD. The data warrant vitamin D supplementation in patients with severe COPD, especially in those carrying at-risk rs7041 variants.

Despite this circumstantial evidence, a recent trial of vitamin D replacement in patients with COPD did not show a reduction in exacerbations unless the patients had a severe vitamin D deficiency.

References:

Vitamin D deficiency is highly prevalent in COPD and correlates with variants in the vitamin D-binding gene. Thorax 2010;65:215-220 doi:10.1136/thx.2009.120659.

http://thorax.bmj.com/content/65/3/215.short
A vitamin D3 dosage of 800 IU/d increased serum 25-(OH)D levels to greater than 50 nmol/L in 97.5% of women http://bit.ly/GzBCcA 

Image source: Lungs, Wikipedia, public domain.

Metformin increases risk of vitamin B-12 deficiency

As many as 22% of people with type 2 diabetes could have vitamin B-12 deficiency.

This BMJ study evaluated the effects of metformin on the incidence of vitamin B-12 deficiency (lower than 150 pmol/l), low concentrations of vitamin B-12 (150-220 pmol/l), and folate and homocysteine concentrations in patients with type 2 diabetes receiving treatment with insulin.

Compared with placebo, metformin treatment was associated with a decrease in vitamin B-12 concentration of -19%.

The absolute risk of vitamin B-12 deficiency (lower than 150 pmol/l) at study end was 7.2 percentage points higher in the metformin group than in the placebo group with a number needed to harm of 13.8 per 4.3 years.

Long term treatment with metformin may increase the risk of vitamin B-12 deficiency, which results in raised homocysteine concentrations. Vitamin B-12 deficiency is preventable; therefore, regular measurement of vitamin B-12 concentrations during long term metformin treatment should be considered.

References:
BMJ 2010; 340:c2181

BMJ 2010; 340:c2198

Image source: Metformin. Wikipedia, public domain.

Correcting Vitamin D Deficiency May Decrease Risk of Heart Disease

Vitamin D is a steroid hormone and a component of a complex endocrine pathway sometimes called 'vitamin D endocrine system' (Medscape, 2012).  In a recent study, 9,400 patients had an average vitamin D level of 19.3 nanograms per milliliter - levels of 30 are generally considered "normal". At their next follow-up visit, 50% of patients had raised their vitamin D levels to above 30 nanograms per milliliter.

Compared with patients whose vitamin D levels were still low, patients who raised their vitamin D levels were 33% less likely to have a heart attack, 20% less likely to develop heart failure, and 30% less likely to die between the two visits (source: WebMD).

"While normal has generally been considered to be 30, some people have suggested 40 or 50 is better. People who increased their vitamin D blood level to 43 nanograms per milliliter had the lowest rates of heart disease and stroke. But increasing it beyond that, say to 60 or 70, offered no greater benefit."

One of the BMJ blogs calls vitamin D "the elixir of life", but it all starts to sound a bit too good to be absolutely true.

What is the best test to diagnose vitamin D deficiency?

Serum 25(OH)D.

The circulating half-life of 25(OH)D is 2 weeks. This is the best test to determine vitamin D status. A 25(OH)D level of less than 32 ng/mL is considered vitamin D insufficient because intestinal calcium absorption is optimized at levels above 32 ng/mL.

A 25(OH)D level of less than 15 or 20 ng/mL have been used to define vitamin D deficiency.

Parathyroid hormone levels start to rise at 25(OH)D levels below 31 ng/mL, which is another marker of vitamin D insufficiency. Although not always required for the diagnosis of vitamin D insufficiency, a serum PTH may be used to help establish the diagnosis of vitamin D insufficiency.

The word vitamin was originally derived from Funk's term "vital amine."

A vitamin D3 dosage of 800 IU/d increased serum 25-(OH)D levels to greater than 50 nmol/L in 97.5% of women http://bit.ly/GzBCcA 

References:
Vitamin D Supplements Lower Heart Disease Risk. WebMD.

Low vitamin D levels in children associated with higher plasma glucose and lower HDL

Vitamin D deficiency occurs frequently in COPD and correlates with severity

Image source: Wikipedia, public domain.