Do I need to take Vitamin D? My latest calcium was 10.7 mg/dl and PTH 60 pg/ml. My doctor is very concerned about my Vitamin D of 15 ng/ml, and says that I should get my Vitamin D level up with supplementation before undergoing parathyroid surgery. Someone else said I should not take Vitamin D. Should I take it? (I am 50 years old.)
This question comes up a lot with parathyroid patients! Most patients with primary hyperparathyroidism will have low or low-normal Vitamin D levels. And many of them are told to take Vitamin D supplements. I do not recommend doing this, and I’ll explain why.
Your labs indicate primary hyperparathyroidism because your calcium is elevated and the PTH is inappropriate for that calcium. When you have high calcium, it does not make sense to take Vitamin D supplements because this can raise your calcium further. One of the main roles for Vitamin D is to help your intestines absorb calcium, thus increasing your blood calcium level. If your blood calcium level is already high, taking Vitamin D supplements can make the situation worse.
Patients with primary hyperparathyroidism often have a diagnosis of “Vitamin D deficiency.” But Vitamin D exists in multiple forms in your body. The one we most commonly measure is Vitamin D 25-OH. This is an inactive form, which gets converted in the body to the active form, or Vitamin D 1,25-diOH. The enzyme that converts the inactive form to the active form is stimulated by parathyroid hormone (PTH). When you have a parathyroid tumor, which produces too much PTH, your inactive Vitamin D is converted to active Vitamin D (which we usually do not measure). Because the inactive form is being used up, primary hyperparathyroidism causes a low inactive Vitamin D. If you measure the active form of Vitamin D in parathyroid patients, it is often high. But we don’t typically measure the active form. If we only check the inactive form, then the patient looks deficient.
Most doctors will not remember this about Vitamin D and PTH (it’s not something they really need to know for most patients). They see a “low Vitamin D” and they automatically prescribe Vitamin D supplementation. But if the calcium level is high, then taking Vitamin D can actually do more harm than good because it can raise calcium further.
The only cure for primary hyperparathyroidism is a parathyroid operation. Read more about primary hyperparathyroidism here. Taking Vitamin D is not going to help until the parathyroid tumor has been removed.
