Secondary hyperparathyroidism

Secondary hyperparathyroidism happens when the parathyroid glands make extra parathyroid hormone (PTH) because something else in the body is pulling calcium or vitamin D levels down. The glands aren't malfunctioning on their own — they're reacting to a problem elsewhere, most often low vitamin D, poor calcium absorption, or declining kidney function. Over time, that extra PTH pulls calcium out of bone to keep blood calcium normal, which can weaken bone.

The most common triggers are chronic kidney disease (where kidneys struggle to activate vitamin D and clear phosphorus), malabsorption conditions like celiac or Crohn's disease, and certain situations like bariatric surgery that reduce calcium absorption in the gut. Some medications, including certain anticonvulsants and long-term proton pump inhibitor use, can also contribute by affecting vitamin D breakdown or calcium absorption. Blood tests typically show low-normal calcium, elevated PTH, and sometimes low vitamin D or abnormal kidney markers.

Treating secondary hyperparathyroidism means addressing the underlying cause rather than the parathyroid glands themselves — for example, managing kidney disease, treating the digestive condition, or adjusting vitamin D and calcium status under medical guidance. This is different from primary hyperparathyroidism, where the gland itself is overactive. Your doctor is the right person to sort out which type is going on and what approach fits your situation.