This transcript has been edited for clarity.
Matthew F. Watto, MD: Welcome back to The Curbsiders. I’m Dr Matthew Frank Watto, here with my great friend and America’s primary care physician, Dr. Paul Nelson Williams.
Paul, we’re going to talk about our primary hyperparathyroidism podcast with Dr. Lindsay Kuo. It’s a topic that I feel much more clear on now.
Now, Paul, in primary care, you see a lot of calcium that is just slightly high. Can we just blame that on thiazide diuretics?
Paul N. Williams, MD: It’s a place to start. As you’re starting to think about the possible etiologies, primary hyperparathyroidism and malignancy are the two that roll right off the tongue, but it is worth going back to the patient’s medication list and making sure you’re not missing something.
Thiazides famously cause hypercalcemia, but in some of the reading I did for this episode, they may just uncover it a little bit early. Patients who are on thiazides who become hypercalcemic seem to go on to develop primary hyperthyroidism anyway. So I don’t think you can solely blame the thiazide.
Another medication that can be causative is lithium. So a good place to look first after you’ve repeated the labs and confirmed hypercalcemia is the patient’s medication list.
Dr. Watto: We’ve talked before about the basic workup for hypercalcemia, and determining whether it’s PTH dependent or PTH independent. On the podcast, we talk more about the full workup, but I wanted to talk about the classic symptoms. Our expert made the point that we don’t see them as much anymore, although we do see kidney stones. People used to present very late in the disease because they weren’t having labs done routinely.
The classic symptoms include osteoporosis and bone tumors. People can get nephrocalcinosis and kidney stones. I hadn’t really thought of it this way because we’re used to diagnosing it early now. Do you feel the same?
Dr. Williams: As labs have started routinely reporting calcium levels, this is more and more often how it’s picked up. The other aspect is that as we are screening for and finding osteoporosis, part of the workup almost always involves getting a parathyroid hormone and a calcium level. We’re seeing these lab abnormalities before we’re seeing symptoms, which is good.
But it also makes things more diagnostically thorny.
Dr. Watto: Dr. Lindsay Kuo made the point that when she sees patients before and after surgery, she’s aware of these nonclassic symptoms — the stones, bones, groans, and the psychiatric overtones that can be anything from fatigue or irritability to dysphoria.
Some people have a generalized weakness that’s very nonspecific. Dr. Kuo said that sometimes these symptoms will disappear after surgery. The patients may just have gotten used to them, or they thought these symptoms were caused by something else, but after surgery they went away.
There are these nonclassic symptoms that are harder to pin down. I was surprised by that.
Dr. Williams: She mentioned polydipsia and polyuria, which have been reported in other studies. It seems like it can be anything. You have to take a good history, but none of those things in and of themselves is an indication for operating unless the patient has the classic renal or bone manifestations.
Dr. Watto: The other thing we talked about is a normal calcium level in a patient with primary hyperparathyroidism, or the finding of a PTH level in the normal range but with a high calcium level that is inappropriate. Can you talk a little bit about those two situations?
Dr. Williams: They’re hard to say but kind of easy to manage because you treat them the same way as someone who has elevated calcium and PTH levels.
The normocalcemic patient is something we might stumble across with osteoporosis screening. Initially the calcium level is elevated, so you repeat it and it’s normal but with an elevated PTH level. You’re like, shoot. Now what?
It turns out that most endocrine surgeons say that the indications for surgery for the classic form of primary hyperparathyroidism apply to these patients as well, and it probably helps with the bone outcomes, which is one of the things they follow most closely. If you have hypercalcemia, you should have a suppressed PTH level, the so-called normohormonal hyperparathyroidism, which is not normal at all. So even if the PTH is in the normal range, it’s still relatively elevated compared with what it should be. That situation is treated in the same way as the classic elevated PTH and elevated calcium levels.
Dr. Watto: If the calcium is abnormal and the PTH is not quite what you’d expect it to be, you can always ask your friendly neighborhood endocrinologist to help you figure out whether the patient really has one of these conditions. You have to make sure that they don’t have a simple secondary cause like a low vitamin D level. In that case, you fix the vitamin D and then recheck the numbers to see if they’ve normalized. But I have found a bunch of these edge cases in which it has been helpful to confer with an endocrinologist, especially before you send someone to a surgeon to take out their parathyroid gland.
This was a really fantastic conversation. If you want to hear the full podcast episode, click here.
Dr. Watto, Clinical Assistant Professor, Department of Medicine, Perelman School of Medicine at University of Pennsylvania; Internist, Department of Medicine, Hospital Medicine Section, Pennsylvania Hospital, Philadelphia, Pennsylvania, has disclosed no relevant financial relationships. Dr. Williams, Associate Professor of Clinical Medicine, Department of General Internal Medicine, Lewis Katz School of Medicine; Staff Physician, Department of General Internal Medicine, Temple Internal Medicine Associates, Philadelphia, Pennsylvania, served as a director, officer, partner, employee, adviser, consultant, or trustee for The Curbsiders, and has received income in an amount equal to or greater than $250 from The Curbsiders.
A version of this article first appeared on Medscape.com.