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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

A challenging case: Dangerously low calcium levels

Imagine you are a doctor and a 49-year-old patient with kidney failure comes to the emergency room with dangerously low blood calcium levels. He is taking activated vitamin D and calcium but still his blood calcium is perilously low.

This actually happened to Dr. Karin Amrein, of the Medical University of Graz, working with Professor Harald Dobnig, who not only helped the patient, they discovered what some had only previously suspected about vitamin D and calcium absorption.

Amrein K, Worm HC, Schilcher G, Krisper P, Dobnig H. A Challenging Case of Hypocalcemia Supporting the Concept That 25-Hydroxyvitamin D Status Is Important for Intestinal Calcium Absorption. J Clin Endocrinol Metab. 2012 Mar 14.

Because his calcium was so low, the doctors put the patient on 9,000 mg/day of calcium and quadrupled the dose of activated vitamin D. It didn’t help. Next, they added regular vitamin D but the patient had malabsorption so they had to give the vitamin D as injections, giving 100,000 IU intramuscularly over a period of several months. Although he was taking a large dose of activated vitamin D, it was only when they added regular vitamin D did the patient’s calcium go up. However, he could not take injections so they put him in a sun-tanning booth, which worked just fine, getting his calcium up, away from dangerously low levels. However, with all this treatment, his calcium was still below normal but no longer in the dangerous range.

During the course of this treatment, the doctors discovered that it takes more than activated vitamin D to increase calcium absorption in the intestine; it appears to take both activated vitamin D and regular vitamin D. To my knowledge, no one knows why, as in the test tube, activated vitamin D stimulates calcium absorption just fine. I also admired the doctor’s ready use of sun tanning beds.

I did find myself wondering about magnesium and wish the doctors had seen if magnesium supplementation would have further improved the patient’s calcium levels. Few doctors appear to know that in some cases of low blood calcium, for reasons unknown, magnesium supplementation will allow the body to use its vitamin D and calcium fully. The case reports of the four patients below detail that fact but only guess at the reason.

Medalle R, Waterhouse C, Hahn TJ.  Vitamin D resistance in magnesium deficiency. Am J Clin Nutr. 1976 Aug;29(8):854-8.

What this all means is simple. If your kidneys are working, take 5,000 IU/day of vitamin D and your body will make all the 25(OH)D and all the activated vitamin D you need to keep your calcium levels in the normal range. If it’s spring or summer, consider an occasional sunbath, and if it’s cold, consider a sun tanning session every once and a while. As far as magnesium is concerned, either eat six servings of fruit and vegetables a day along with plenty of seeds and nuts or take a magnesium supplement.

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

14 Responses to A challenging case: Dangerously low calcium levels

  1. Liz says:

    Thank you for this blog, Dr Cannell.

    We have discovered the need for D3 ourselves as patients with Hypoparathyroidism . Without parathyroid hormone our D3 can’t become activated so many doctors feel that we don’t need D3 and that low levels are irrelevant to us. Not so. I spend a lot of time raising awareness about this and trying to convince doctors that we need D3 as well as Alfacalcidol or Rocaltrol. D3 and magnesium both make a huge difference to our calcium stability along which the usual treatment of Vit D analogues and a maximum of 2000mg of calcium frequently fail to do.

    One of our Professors says “Well, it is now recognised that many tissues of the body can
    manufacture small amounts of ‘active’ vitamin D without the help of
    PTH. For instance, the important role vitamin D is known to have in
    immune system function is carried out independently of PTH, with
    the immune cells having the capability of activating their own
    vitamin D. These ‘non-endocrine’ vitamin D effects are believed to
    occur locally in different tissues and are not reflected in the blood
    levels of activated vitamin D. So, it is certainly possible that the
    colecalciferol (D3) you take has a local action in your gut to stabilise
    the absorption of calcium.

  2. Brant Cebulla says:

    Liz, in your hypoparathyroidism community, what kind of vitamin D dosing range do you typically see to be able to maintain serum calcium?

  3. paraprob says:

    I started taking more vitamin d when I read that it could help with hyperparathyroidism and my PTH levels did drop-A LOT, in fact to below the normal range. Then in a couple of months PTH was in the normal range and I was very encouraged. But then in my most recent blood work last month PTH was back up despite my vitamin d levels being even higher. Calcium has been high and remained high no matter what the PTH was. Has anyone seen anything like this or know what could be going on?

    • Brant Cebulla says:

      paraprob, what specifically were your 25(OH)D and 1,25(OH)2D levels when PTH was normal (before) compared to when PTH and calcium were back up (most recently)?

  4. paraprob says:

    In October calcium was 11, PTH was 3.7, and 25 (OH) D was 67 ng/mil
    PTH was retested in November and came in less than 2.5
    In December calcium was 10.5, PTH was 68, abd 25(OH) was 61
    Last month (March) calcium was 11.3, PTH was 161, abd 25(OH) D was 82

    • Brant Cebulla says:

      paraprob, you need a 1,25(OH)2D drawn as well to determine what kind of hyperparathyroidism you have.

      If 1,25 is normal to high as well, you likely have primary hyperparathyroidism and you have a benign tumor in one of your parathyroid glands. If 1,25 is low, you may be having a problem producing it in the kidneys, despite having a high level of 25(OH)D. This would be secondary hyperparathyroidism caused by kidney disease.

      Either way, you should be working with a knowledgeable doctor!

  5. paraprob says:

    That is the standard answer but how do you explain the super low PTH readings last fall, especially with high calcium? Tumor went away and came back again? Does not seem likely. And if it went away why was calcium still high with super low PTH? If my doctor knew why I would not be asking here.

    • Brant Cebulla says:

      Well, you need a 1,25(OH)2D drawn to be able to come to an informed conclusion.

      Another possibility is tertiary hyperparathyroidism. Tertiary hyperparathyroidism occurs after a long period of secondary hyperparathyroidism and hypercalcemia. The parathyroid glands no longer respond to excess serum calcium. The treatment of choice is usually surgery.

      Could be the case that while your parathyroid initially responded to an increase in 25(OH)D and 1,25(OH)2D, your glands have been subjected to secondary hyperparathyroidism for such a long time, that your calcium receptors in your parathyroid no longer respond to increased serum calcium.

  6. gerskan says:

    About 18 years ago my wife was treated with overlapping IV Vancomycin and IV Clindomycin for a serious dental infection. In 2 days she was suddenly in full- body tetany and screaming in almost uncontrollable pain. (Treated with Ativan, Demerol, Valium, Morphine and a couple other things I can’t remember now.) The ER Doc said, “Okay, you can take her home now.” This was now 2 hours after first pain meds were given, which means in 1 hour the injected narcotics start coming off quickly. She was now only half-screaming with every breath. I insisted and fought, finally forcing an admission to the hospital. She was hospitalized in enormous pain and not released for 4 days. 2 Weeks later we did it all again. Her serum calcium was at the low limit of normal so the docs refused to supplement calcium as she was “normal”. At the beginning of her 4th attack in 2 months, I asked a new doc if we could give a gram or two of IV calcium. He looked it up, scratched his head and said “Sure, let’s give it a try”. 45 minutes later the spasm stopped completely. No hospitalization required. But, since the IV antibiotic misuse, parathyroid hormone levels had been low as well, well out of the normal range. I’m assuming this (antibiotic damage to parathyroid glands?) actually triggered all the calcium/tetany problems. We discovered that aggressive calcium supplementation could keep her out of hospital and she would suffer relatively minor muscle spasm. 10 years later we discovered Dr. Cannell and the info on Vitamin D deficiency. We began to supplement and test D & PTH levels regularly. Her D levels gradually increased with 15-20 thousand units/day. PTH remained low and muscle spasm was a continuing problem. Last year, as her Vitamin D (OH25D) levels reached 102 nanogram/mole, (top of Canadian current normal range) her PTH levels suddenly increased to normal and and calcium needs dropped to <500 mg/day to maintain spasm-free conditions. It appears higher levels of Vitamin D restored/healed the damage done years ago to her PTH glands. All health concerns are improved, including improved mental function and improved/restored memory ability. short and long term. Any guesses on whether we should try to attain higher OH25D levels?

    • Brant Cebulla says:

      Based on what we currently know on vitamin D, PTH and calcium, I would say no, there is no reason to raise levels higher than 100 ng/ml — that is very high, though not potentially “toxic.”

  7. marthaarnold@me.com says:

    What is the best form of magnesium to take along side of Vitamin D3?

  8. Gary says:

    You may find that adrenal fatigue has some effect on availablity of minerals specifically through the action mineralocorticoids have on mineral balance. A drop in sodium can cause calcium to leech to intracellular compartments and make it less available to general metabolism.