I have been feeling awful for the last 6 months. I'm 60 years old but feel like 90. I'm tired all the time, even after a nap (and I never needed naps before). The only abnormality I have on labs is a calcium level of 10.4 mg/dl, but my doctor tells me that this isn't high enough to cause symptoms. I don't have any other explanation. Could this cause my symptoms?
A calcium level of 10.4 mg/dl (2.59 mmol/l) is definitely high enough to cause symptoms. At your age, this calcium level is too high, and usually indicates primary hyperparathyroidism. (We would also need a PTH level to confirm - if your PTH is in the high or “normal” range, then we could diagnose parathyroid disease.)
One interesting thing about parathyroid disease is that the calcium level does not correlate with symptoms. Meaning, a calcium level of 10.4 is just as likely to cause symptoms as a calcium of 11.4. Both are high, and both are likely to cause symptoms. The most common symptom of parathyroid disease is fatigue, exactly what you are feeling. It is very common for people to describe feeling tired all the time, even after a night’s rest or a long nap.
The next step is to figure out whether your high calcium is due to a parathyroid tumor. Most cases of high calcium are due to a parathyroid tumor, but we need the PTH level to confirm. A normal or high PTH level would be inappropriate for a calcium of 10.4, and would thus undicate primary hyperparathyroidism. Another cause of high calcium is high-dose Vitamin D supplementation, so if you are taking Vitamin D you should stop now, and we would want to check Vitamin D levels.
If you do have primary hyperparathyroidism, then you want to get it treated. Most people notice significant improvement in their symptoms in the weeks after parathyroid surgery, which is the only way to cure primary hyperparathyroidism. Your fatigue is a classic symptom.