Understanding calcium–PTH–vitD patterns when the numbers don’t line up

Many people notice situations where:
• Calcium is high-normal or slightly high
• PTH is “normal” but not suppressed
• Vitamin D sits in the low or borderline range
• 24-hour urine calcium may be low, normal, or high depending on the person

Clinicians sometimes call this “inappropriate PTH” or “secondary hyperparathyroidism,” while others say it could still be early or normocalcemic primary hyperparathyroidism.

My question is:

How do endocrinologists actually interpret this pattern in real life?
For example:
• When does a normal-range PTH still count as “abnormal” because calcium is elevated?
• How much does vitamin D status change the interpretation?
• Do specialists rely more on biochemical patterns than on scans?

I’m not asking for medical advice — just hoping to understand the logic clinicians use so patients can ask better questions at appointments.

Thanks to anyone who can explain how professionals sort through these cases.