High Calcium and PTH: A Definitive Diagnosis
For most people, the first sign that you might have hyperparathyroidism is a high total calcium level on a routine blood test, perhaps one you had done for your annual physical. A high calcium level is not, on its own, enough to diagnose hyperparathyroidism. It should, however, always raise the question of hyperparathyroidism and prompt a follow-up test.
What counts as “high” calcium? Well, it varies slightly by age. Teenagers and young adults naturally have higher calcium levels in their blood. They need it to build those fast-growing bones and muscles. So a somewhat higher calcium level in a teenager might be perfectly normal but much too high for an adult. The normal range for adults is between about 9 and 10 mg/dL. A calcium level as low as 10.2 in a mature adult should be taken seriously. 10.3 or 10.4? You should definitely get tested.
The follow-up is simple: a test of the parathyroid hormone (PTH) level in your blood. If you have both high calcium and high PTH, the diagnosis is clear: you have hyperparathyroidism. Once we find the overactive parathyroid gland, we know how to cure it.
If your PTH level is in the normal range, diagnosis is slightly more complicated. With healthy parathyroids, a higher calcium level should lead to a lower PTH level. So a PTH level in the normal range can still be too high when we consider it alongside your high calcium level. If it is, we again can diagnose hyperparathyroidism. And again, we know how to cure it.
If, however, your PTH level is appropriately balanced to your high calcium level, then something else is going on. You have, at least, now eliminated one likely cause of your high calcium.