Thursday, September 1, 2011

Vitamin D3 and High Serum Calcium

At my last Mayo Clinic visit, serum calcium tested at an all-time high, 10.5 mg/dL. The reference range is 8.9 to 10.1 mg/dL, so it's significantly above normal. Why is that? (1) It could be the myeloma attacking a bone somewhere; or (2) Dr LH noticed that I take a lot of Vitamin D3 and Vitamin K2 supplements, and decided to measure INR and Vitamin D levels. INR was OK.

Vitamin D levels came back the next day, and a couple of days after that Dr LH called to discuss them:

Test Name Result   Units
25-Hydroxy D2 <4.0 ng/mL
25-Hydroxy D3 71 ng/mL
25-Hydroxy Total 71 ng/mL   Total (D2+D3) optimum level is 25-80 ng/mL

Dr LH pointed out that the Total Vitamin D is near the high end of the optimum range, and suggested that I cut my Vitamin D3 from 5000 units per day to 2500 per day, which is easy enough to do. Arguments for doing that (these are from my own research):
  • Some authorities believe that it is possible for continuously-high levels of Vitamin D to cause high serum calcium.
  • In some individuals, high levels of calcium can result in deposition of calcium in arteries, atherosclerosis.
  • There is really not enough research to determine the safe amount of supplementation.
Arguments against reducing Vitamin D supplementation:
  • According to the Vitamin D Council, toxicity begins at about 200 ng/mL and higher. They suggest an upper limit of 100. Other authorities seem to agree, though research on humans is lacking and individual responses could vary widely.
  • The purpose of the high Vitamin D3 intake, along with Vitamin K2, is to combat bone loss. In a one-year test this seemed to be effective, with two density scans a year apart showing no measurable difference in density. It's just one short test, but I'm reluctant to make a change that might reduce the effectiveness of this treatment.
So what to do? My serum calcium levels have varied widely in recent months. Below is a chart of recent measurements.

Possibilities: cut the Vitamin D3 supplement in half or leave it the same for the current cycle, and, either way, the serum calcium might stay high or it might go down. But if I cut the D3 in half and calcium remains high, then we should worry about a myeloma hot spot in a bone somewhere. That's the worst case scenario here, so let's check for it.

Blood Calcium Chart


  1. Good analysis. I work in the supplement industry and I am a biochemist. I have a strong understanding of D3 and K2 and calcium metabolism. One thing I see as a possible issue of why your serum calcium could be high is that you arent getting enough K2. What is the dose you are taking and from where? There are a number of companies that sell a mislabeled vitamin K2 product on the market. For a dose of 5000 IU of D3, you would need at least 150-200mcg of K2 to keep up. Remember that K2 is the calcium potentiator and responsible for activating the proteins that remove calcium from serum and soft tissue and puts it on your bone, where it is needed. If you are taking K2-4 for example, the half life is a few hours and if you are taking it once a day, you are not getting the effect you need. K2 and D3 have to work together to move calcium where it needs to be. If they arent being used in matching dosages, you are going to get an imbalance of calcium that will be found in the circulation and soft tissue.

  2. Thanks Kirk,

    I'm taking 30 mg of K2, Carlson 5 mg caps of menatetrenome, three caps in the morning and three in the afternoon. But I've been taking the same amount for about three years, and this is the first time that calcium has gone so high.

    Thanks for your advice.


  3. Do you supplement with magnesium?
    Magnesium is a natural calcium channel blocker and it generally counterbalances the actions of calcium.
    I always suggest that people who use Vitamin D at effective strength also use magnesium. Generally most people have a lower than RDA intake for magnesium and most people who've studied the many roles of magnesium in the body think the RDA is way too low (same story as Vit d3)
    Nutritional Magnesium
    Here's another good source of info
    Krispin on magnesium
    I use an Albion Mineral Patent chelate form that well absorbed. Only 4% of magnesium oxide is absorbed so ignore that if it's in your mutlivit.
    Mag Malate or Aspartate, or Taurate are also reasonable. It's best taken in small amounts through the day with food.
    I presume you've cut all supplemental sources of calcium from you diet.

  4. Has your PTH level been measured?


  5. No. They do check thyroid every three months, but not parathyroid. I'll ask about that at the next visit. Thanks.