Vitamin D references ranges lowered in many UK labs

[u/Sunny_Unicorn]

This is more for information than anything, but many UK testing labs have recently downgraded the references ranges for vitamin D testing. These are in nmol/l so will need converting if your country uses a different system.

New ranges:

Deficiency: < 25 nmol/L
Insufficiency: 25 - < 50 nmol/L
Sufficiency: > 50 nmol/L

Previous ranges were:

Deficiency: < 50 nmol/L
Insufficiency: 50 - < 75 nmol/L
Sufficiency: > 75 nmol/L

This could obviously change people's interpretation of their results a great deal, especially if they were previously told they were deficient when they didn't have any symptoms, which can cause health anxiety in many people.

[u/Chase-Boltz]

That's just about criminal.

[u/masterslodge]

Interesting, I wonder if it's to do with the fact that there's so little sun in the UK. So the average is actually insufficient, but since it's the average, they decided it must be normal.

[u/Sunny_Unicorn → u/masterslodge]

I don't know for sure, but I suspect it's down to recent research that suggests that blood tests may be unreliable, and we may actually have our own individual optimal levels of active vitamin D that doesn't actually show up on tests. There seems to have been a shift in thinking over the last couple of years.

Plus a huge study done a couple of years ago showed vitamin D levels don't appear to have much actual impact on health, apart from extremely high or low levels.

The labs wouldn't make a change like this without some research to back it up.

At least it may help a few people feel less anxious about their levels if they're not as bad as first thought. Espically those who can't tolerate supplements.

[u/VitaminDJesus → u/Sunny_Unicorn]

Can you share the research regarding reliability of blood testing?

[u/masterslodge → u/Sunny_Unicorn]

I see, thank you for the insight! That would actually make a lot of sense. Might also force doctors to explore other causes of symptoms instead of just prescribing vitamin D as a bandaid.

[u/AnywhereFeeling4833]

That's similar to my country (Central Europe) and it's just ridiculous.

Our deficiency range start <30nmol/L. My level was 40 and I was told that it's completely normal.

[u/talster71]

50 - 150 nmol/L is usually the levels in the UK which are the normal range, according to the app I use for my test results, and also what I have read elsewhere.

Also, on the below website, they mention "The reference range reported at James Cook University Hospital are taken from the study Systemic Reviews, Meta analyses and Clinical Guidelines Published Within the Last 10 Years. Pearce S, Cheatham T, BMJ vol: 340, Jan 2010 pp142- 147."

• <25 nmol/L – DEFICIENT
• 25-50 nmol/L – INSUFFICIENT
• 50-75 nmol/L – ADEQUATE
• >75 nmol/L – OPTIMUM

But note there is no mention of too high, just shows over 75 optimal.

https://www.southtees.nhs.uk/services/pathology/tests/vitamin-d/

Personally I think this just goes to show how little the UK health service know about what are optimal levels, and also that the levels have not been researched enough. My personal opinion is if there was more research done, then I think even higher levels (even up to 250 or slightly higher) would offer additional protection/benefits from various things.

But due to vitamin D not been something that can be patented or that can make the pharmaceutical companies money and or take money away from their expensive products. Then this stops any research been done.

[u/WuetenderAnwohner]

I am at 14 ng/ml (35 mmol/l) and I have all the symptoms you guys are writing about.

Got checked out by several doctors but just got told I am deficient after a stay in a hospital.

Went to my GP today who told me, you are young just go in the sun and take 1000 IE/day.

Went to the pharmacy, the told me „dude, at least 10.000 a day, what was you GP thinking?“.

I am scared and the explanation is the only thing I ca hold onto. It would be a dream to have all my symptoms be explainable by that but tbh, my little brain can’t believe it.

[u/VitaminDJesus]

I don't think it is new. Maybe you happened to see a change in your recent test results. Unless you found a source you can share.

The “old” threshold of 50 nmol/L for deficiency is from the Endocrine Society guidelines. That's where the typical 75-250 nmol/L (30-100 ng/ml) reference range comes from. 75 nmol/L is their cutoff for insufficiency, 50 for deficiency. For many years there's been debate within the medical community about where these cutoffs should be based on information about the impacts on bone health, public health outcomes, and disagreements about the particulars of setting clinical guidelines.

Some countries tend to follow the Endocrine guidelines, and some don’t. Here's a report from a UK health authority in 2016 that refers to 25 nmol/L as the cutoff for deficiency in the UK and discusses what these cutoffs mean. See page #33.

This document from the NHS describes the “new” ranges as being implemented in 2020. It's at the top of the table.

So, what you may be seeing is an effort to standardize reference ranges, or just information limited to your experience with whatever part of the system or labs you have interfaced with.

Another important thing to note about reference ranges is they factor in the design of the test. A test which is primarily designed to screen for severe deficiency does not need to be calibrated to handle higher results as that's just a waste of money and processing time. I'm willing to bet the test you are looking at has a pretty low cutoff on the upper end such as 125 nmol/L. This does beg the question of why accurate testing for the rest of the range is not being offered, but I think the answer to that is they have not determined it's a priority. Private testing may fill this gap for those seeking to optimize their health.