Hey Abby,
Educating physicians on vitamin D3 therapy will continue to be an issue with many of them... Unless they've had some recent continuing medical education in vitamin D3 therapy... most are clueless. In your case with a PCP following your neurologist's recommended treatments... it sounds like you've got the blind leading the blind.
Physicians are what they were when they went through med school... and most medical schools teach 400 IU/day vitamin D3 is sufficient. IT ISN"T !!!
Show the following charts to your PCP when you see him for your labs in two weeks.
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I'll make the assumption because you're in the UK that your 25(OH)D serum concentration was measured in nmol/L. If that's the case, your 25(OH)D works out to 101 ng/mL.
Vitamin D3 toxicity is very rare. Assuming no thyroid or parathyroid problems, the best estimates are it would take a serum concentration in excess of 500 nmol/L, (200 ng/mL) to reach the lower threshold for vitamin D3 intoxication.
The simple thing to do is have your PCP test your total calcium and PTH (parathyroid) serum concentrations when he dose the 25(OH)D lab test. As long as both calcium and PTH are in the normal range, there's no indication of vitamin D3 toxicity.
Now for the real question... Howz the head? Have you experienced any reduction in the frequency, severity or duration of your cluster headaches?
If not, "tuning" the rest of the anti-inflammatory regimen is in order.
Your 25(OH)D serum concentration is in the green zone at 252 nmol/L... That's good!
Dropping back to a dose of 5,000 IU/day vitamin D3 is ok... but your 25(OH)D will drop to around 150 nmol/L, (60 ng/mL) in a few weeks.
What kind of magnesium are you taking and how much? We've found that magnesium malate, magnesium glycinate or magnesium citrate work best... 400 mg/day should be sufficient.
Several CH'ers have reported they needed more Omega-3 Fish Oil... up to 2000 mg/day.
You can also cut your calcium supplements in half.
You may have a low arterial (systemic) pH... (too much acid). The body senses this condition and triggers vasodilation in response. That makes cluster headache medications, vitamin D3 and oxygen less effective.
If this is the case, you can try a baking soda tonic 4 times a day... an hour after each meal and just prior to bed time. That's a half teaspoon of baking soda in 4 ounces of water. Taking an Alka-Seltzer 3 to 4 times a day may help as well to raise your systemic pH.
If alkalizing your system helps, going on a GOMBS diet is the next step. GOMBS = Greens, Onions, Mushrooms, Beans-Berries and Seeds (including nuts). A handful of each a day will do for starters.
See the following link for details:
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Finally, regarding clinical trials of vitamin D3... There have been over 570 since 2000 and 375 since 2010. Over 30 of these RCTs have been done to the gold standard, (randomized, placebo controlled and double blind.
Unfortunately only three dealt with headaches and none were conducted on cluster headache patients.
If you'll pass me your neurologist's email address I'll be happy to send him the results of the survey of CHe'rs using the anti-inflammatory regimen with 10,000 IU/day vitamin D3. To date, the raw efficacy of this regimen is 80% with 70% experiencing a pain free response.
It's not a gold standard study but the empirical results indicate a clear causal relationship between a vitamin D3 deficiency and cluster headache.
Take care and please keep us posted.
V/R, Batch