Normocalcemic primary hyperparathyroidism (NPHPT) occurs when a patient’s parathyroid hormone level is elevated but their calcium level is within normal range. While this condition isn’t well observed or understood by many in the medical community, Tampa General Hospital’s Parathyroid & Thyroid Institute is making strides and providing the greatest options in care to patients. In fact, no surgeons operating today at any other hospital in the world perform more parathyroid procedures than TGH’s surgeons.
The parathyroid glands are four small, rice-shaped structures located behind the thyroid at the base of the neck that help regulate the body’s calcium levels. Primary hyperparathyroidism occurs when one or more parathyroid glands becomes abnormal and triggers an overproduction of parathyroid hormone (PTH), causing blood calcium levels to rise (a problem known as hypercalcemia[JP1]). NPHPT is considered by some professionals to be an early form of primary hyperparathyroidism, as it is found before blood calcium levels are impacted by PTH overproduction.
Causes of Normocalcemic Primary Hyperparathyroidism
Research from the National Library of Medicine says normocalcemic primary hyperparathyroidism affects 6% to 8% of people with primary hyperparathyroidism. The exact causes of NPHPT aren’t clear, but primary hyperparathyroidism in general usually results from a noncancerous growth (adenoma) on one or more parathyroid glands or gland enlargement (hyperplasia). Almost never, parathyroid cancer is the cause of primary hyperparathyroidism.
Normocalcemic Primary Hyperparathyroidism Symptoms
The hallmark symptoms of primary hyperparathyroidism result from organ and tissue damage caused by elevated calcium levels. Curiously, many people with normocalcemic primary hyperparathyroidism also experience symptoms like those of hypercalcemia, which may involve:
- Bone loss (osteoporosis)
- Joint pain
- Muscle weakness
- Kidney stones
- Frequent urination
- Increased thirst
- Loss of appetite
Diagnosing Normocalcemic Primary Hyperparathyroidism
Diagnosing normocalcemic primary hyperparathyroidism can be complex. Unlike primary hyperparathyroidism, NPHPT does not cause high blood calcium levels that are easily detectable on a routine blood test—and without elevated calcium levels, testing PTH levels is rarely considered necessary. NPHPT is oftentimes discovered only after investigating the cause of a patient’s low bone mineral density or osteoporosis.
Normocalcemic Primary Hyperparathyroidism Treatment
Surgery to remove the abnormal parathyroid gland or glands (a procedure known as a parathyroidectomy) is the standard treatment for most types of hyperparathyroidism, including normocalcemic primary hyperparathyroidism. When surgery is not advisable, therapies to control NPHPT symptoms may be recommended.
No surgical team in the world has more experience performing parathyroidectomies than TGH’s Dr. Douglas Politz and Dr. José Lopez. Combined, our globally renowned surgeons have completed more than 14,000 parathyroid procedures and possess nearly three decades of clinical experience.