I have some confusion on vitamin D testing supplementation. On testing, 25-D is 34. It’s just slightly, though, and 25-OH D2 as the lab has notated it is below 4, expressed in nanograms per milliliter. On the functional level, D2 in the blood chem manual should be 19 to 79.3.

Okay, I think there may be some confusion here. The main things here—this goes to the second question too—the main things you’re assessing in a lab workup with vitamin D are twenty 25-D, so that’s the one that’s typically measured, and that’s cholecalciferol, and then you’re measuring calcitriol, which is 125-D, that’s the more active form of vitamin D. And then, you also want to measure parathyroid hormone because that can help give you some indication of whether there are biologically sufficient levels of vitamin D present. Those are the ones that you’re really looking for. it’s pretty confusing, so I think if you’re confused, don’t worry about it. It takes a while to get your head around this. So, 25-D is the best marker overall of your vitamin D status. If someone is deficient, then that’s the one that’s going to drop. If they have too much, that will go up. Calcitriol 125-D will often be high as well if someone is taking too much. But as I believe I mentioned in the course materials, high calcitriol, or 125-D, is not always a sign of excess vitamin D. It can also be a sign of calcium deficiency, not having enough calcium. If you see a normal 25-D, for example, and parathyroid hormone is at around 30 or below, then that would suggest that there is enough biological activity of vitamin D, and if calcitriol, or 125-D, is high in that situation, then that would be more likely to be a calcium deficiency. Unfortunately, it’s very difficult to assess calcium in any body tissue, including the serum, because calcium is so tightly regulated in the blood. It’s so important to maintain a certain narrow range of calcium in the blood that the body will do anything it can to maintain that level.

This is why if calcium intake in the diet is insufficient, the body will take calcium out of the bone in order to maintain a normal serum calcium, and that’s of course why inadequate calcium intake is linked with osteopenia and osteoporosis. Ionized calcium, as we discussed in the blood chemistry unit, is better than serum calcium, more accurate, more likely to reveal calcium deficiency, and also 24-hour urine calcium is too. Those are options, but one of the best ways of doing it is a low-tech way. Well, there’s some tech involved, but using Chronometer, an app, have the patient carefully track their food intake over a three-day period, and even weighing and measuring food, and then that will spit back a report on the micronutrients, including calcium, and average adults should be at about 1,000 mg per day, a pregnant woman or woman trying to conceive or a woman who is breastfeeding or an elderly adult should be at 1,200 mg. It’s really rare, actually, in my experience for someone to do this testing and for them to be at or above that level unless they’re eating dairy products or significant amounts of bone-in fish or just really paying attention to it. This is one reason why full-fat fermented dairy can be a really helpful part of the diet as long as it’s well tolerated by the individual because it’s one of the most bioavailable sources of calcium.