The parathyroid glands are four tiny glands (each about the size of a grain of rice) located behind the thyroid in the neck. Despite their small size, they play a critical role in regulating calcium and phosphorus levels in the blood. Disorders of the parathyroid glands — most commonly hyperparathyroidism — are frequently managed by endocrinologists.
Parathyroid Hormone (PTH) and Calcium Regulation
When blood calcium falls too low, the parathyroid glands release PTH (parathyroid hormone), which raises calcium by:
- Stimulating the bones to release calcium into the blood
- Telling the kidneys to retain calcium (rather than excrete it in urine)
- Activating vitamin D to increase calcium absorption from food in the intestines
When calcium rises too high, PTH secretion is suppressed. This elegant feedback system maintains a very narrow normal calcium range.
Primary Hyperparathyroidism
The most common parathyroid disorder. One or more parathyroid glands produces excess PTH despite normal or elevated calcium. Usually caused by a single benign tumor (adenoma). Most commonly diagnosed incidentally when blood tests show elevated calcium (hypercalcemia).
Symptoms: "Bones, stones, groans, and psychic moans" — bone pain and osteoporosis, kidney stones, abdominal pain/nausea/constipation, fatigue, depression, and cognitive changes. Many patients are asymptomatic.
Diagnosis: Elevated serum calcium + elevated (or inappropriately normal) PTH. Vitamin D, 24-hour urine calcium, kidney function, and DEXA scan are also evaluated. Neck ultrasound and sestamibi scan locate the abnormal gland(s).
Treatment: Surgery (parathyroidectomy) is curative and the definitive treatment. Medical monitoring is appropriate for asymptomatic patients with mild disease who don't meet surgical criteria.
Secondary Hyperparathyroidism
The parathyroid glands overproduce PTH in response to low calcium or vitamin D deficiency. Common in chronic kidney disease, vitamin D deficiency, and malabsorption. The calcium is typically normal or low (unlike primary hyperparathyroidism). Treatment targets the underlying cause — vitamin D and calcium supplementation for deficiency; phosphate binders and calcimimetics for kidney disease.
Hypoparathyroidism
Deficiency of PTH leading to low blood calcium (hypocalcemia). The most common cause is accidental damage to or removal of parathyroid glands during neck surgery. Symptoms of low calcium include muscle cramps, tingling in the hands/feet and around the mouth, muscle spasms (tetany), and in severe cases, seizures. Treatment: calcium supplements and high-dose activated vitamin D (calcitriol). Recombinant PTH (Natpara) is available for patients who are difficult to control on conventional therapy.
Hypercalcemia — Other Causes
Not all elevated calcium is due to parathyroid disorders. Other causes include cancer (malignancy-associated hypercalcemia — the most common cause in hospitalized patients), granulomatous diseases (sarcoidosis), and excess vitamin D. Distinguishing between these causes — primarily through PTH measurement — is key to appropriate management.
Key Takeaways
- PTH regulates blood calcium — the parathyroid glands are essential for calcium balance
- Primary hyperparathyroidism is common, often found incidentally on routine blood work
- Surgery cures primary hyperparathyroidism in >95% of cases
- Low calcium after neck surgery suggests hypoparathyroidism — requires prompt treatment
- Not all high calcium is parathyroid-related — PTH measurement distinguishes the cause
Our Team Sees Calcium & Parathyroid Patients
All five of our providers evaluate and manage calcium & parathyroid conditions. Book with any member of our team:
Book an Appointment → or call 832-968-7003