If you are testing for vitamin D, don’t forget the calcium!

You name it, vitamin D now appears to fix it! Everything from osteoporosis through to psoriasis and even depression would benefit from a dose of vitamin D if you follow the research; it has become the ‘must take’ vitamin.

While cases of vitamin D toxicity in adults are rare. The Vitamin D Council warn that very high intake doses (10,000 – 40,000iu) taken over a few month of so can cause problems as well as single intakes of 300,000iu over a 24-hour period. However, worries over vitamin D and its potential for toxicity has filtered into the realms of urban myth and legend, probably prompting the surge in vitamin D testing we are now experiencing. On the surface of it this sounds like a good idea. Get a test; if you result is low take vitamin D… simple!

For most, a low vitamin D result is exactly that, a low level of vitamin D. Taking some vitamin D supplements is the answer if you are not in a position to move to the equator and get some Sun. For others, the story may take an interesting twist since the body, in its wisdom, may actually want you to have a low vitamin D level. To understand this we need to take a quick look at calcium. The calcium in your blood is always kept within very narrow limits and an abnormal calcium level is exactly that; abnormal! Be aware, the blood calcium level cannot be used to determine if you have adequate dietary intake. You can have a perfectly normal blood level on a diet quite lacking in calcium.

The body has a very effective hormonal mechanism that maintains blood calcium levels within very narrow parameters. A deviation from the normal always needs further investigation since it probably reflects a hormonal problem rather than a simple dietary one. The most common disorder that causes a detectable change in blood calcium levels is hyperparathyroidism. The parathyroid glands (there are four  of them!) sit behind the thyroid gland in the neck and release parathyroid hormone (PTH) that regulates blood calcium levels. An increase in blood calcium is most commonly due to an over production of PTH ie. hyperparathyroidism. Interestingly, having an elevated calcium level supported by an additional test for PTH levels is all that is needed to diagnose hyperparathyroidism in 95% of cases. To help reveal this problem it would be advisable to test for calcium at the same time as vitamin D to screen for parathyroid disease because this is one of the common hormonal disorders responsible for the thin bone disease osteoporosis. In essence, if the blood calcium is high and the blood vitamin D is LOW, then you have a parathyroid problem unless proved otherwise. This is important because taking vitamin D to increase the low level in a hope that this in turn regulates the calcium level is not the way forward and can actually be rather hazardous!

A bit about your vitamin D result

If your test shows that your vitamin D is low, there are 2 key causes to consider;

  1. Low vitamin D (with normal or low calcium) is common in people without any other obvious health problems simply because they are deficient and need a top up.
  2. Low vitamin D (with high calcium) is seen in people with a parathyroid disease.

Taking vitamin D supplements in the first case is a good move but taking it in the second case is not! However, don’t just take it from me. Dr James Norman MD is probably the world expert on parathyroid disorders. Having performed over 18,000 operations on the gland what he does not know about the parathyroid is not worth knowing.

Regarding the relationship between calcium and vitamin D, Dr Normal comments that: “Since vitamin D is required for humans to absorb calcium in their intestines, a low vitamin D cannot ever be the cause of high blood calcium. This fact is not debatable. Thus, if you have a low vitamin D and your calcium is high then the high calcium in your blood must have come from somewhere else other than your diet. This calcium comes from your bones almost guaranteed as a result of parathyroid disease.” The reason your vitamin D levels are low in the face of high calcium reflects a natural protective mechanism. Again, Dr Normal puts it clearly; “If your body determines that your calcium is too high… it can decrease the amount of calcium that is absorbed from your intestines by decreasing the amount of Vitamin D available. If your Vitamin D levels are decreased, you can’t absorb so much calcium from your diet. This is a protective measure.”

To summarise, if you are going to the trouble to test for vitamin D seriously consider testing for calcium at the same time.

By Marcus Webb

Holistic health expert and author
Marcus Webb ND is the technical director of Hadley Wood Healthcare (www.hhcproducts.co.uk) and serves on the editorial board of the peer-reviewed open access publication, the Natural Medicine Journal. He is also on the medical advisory board of Fibromyalgia (UK)