Question

Is this primary hyperparathyroidism? Over the last year my calcium levels have been: 10.5, 10.9, and 10.6 mg/dl. My PTH was 57 pg/ml. I'm 75 years old. My physician said that my PTH is normal and so this cannot be primary hyperparathyroidism.


Answer
Deva Boone
Answer authored by Deva Boone
Deva Boone, MD is the founder of the Southwest Parathyroid Center. As one of the most experienced parathyroid surgeons in the U.S., she has treated thousands of patients with parathyroid conditions.

These are classic labs for primary hyperparathyroidism. Your calcium is high for your age. PTH levels can only be interpreted in relation to calcium levels. If your calcium is normal, then you expect the PTH to be in the “normal” range listed on the lab result. But if the calcium is high, normal parathyroid glands will be suppressed, and thus the PTH should be low (under 20 pg/ml). If the PTH is in the “normal” range, but the calcium is high, this is an inappropriate response of the parathyroids. The parathyroids are making more PTH than they should, which is hyperparathyroidism. 

In general, labs that show a high calcium combined with a high or normal PTH are consistent with primary hyperparathyroidism. 

Sometimes the presentation of high calcium and normal PTH is called “normohormonal primary hyperparathyroidism.” I do not like this term and do not use it, because a PTH in “normal” range is not truly normal if the calcium is high. Normal parathyroid glands should not make that much PTH in the presence of high calcium, so I feel that the term “normohormonal” is misleading. 

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