Parathyroid glands are small endocrine glands that play a central role in maintaining the body’s calcium balance, essential for nerve, muscle, and bone function. Despite their small size, their precise location holds significant implications for overall health and medical procedures.
Their Typical Home
Most individuals have four parathyroid glands, usually situated in the neck. These glands are commonly found embedded on the posterior surface of the thyroid gland. Each gland measures about 6 millimeters long, 4 millimeters wide, and 2 millimeters thick, with a yellowish-brown, oval appearance.
The two superior glands tend to have a more consistent position behind the upper part of the thyroid. The two inferior glands, however, can show more variability in their exact placement. Despite their close association with the thyroid, parathyroid glands are distinct and produce parathyroid hormone (PTH) to regulate calcium levels.
When They’re Not Where Expected
While four parathyroid glands are typical, their number can vary. Their location is not always standard, a phenomenon known as ectopic parathyroid glands. Around 16% of people may have at least one ectopic gland.
These ectopic glands can reside in various locations due to developmental migration. Common atypical sites include higher in the neck, within the thymus, or along the esophagus. Less common locations include within the thyroid or deeper in the chest.
How They Are Identified
Healthcare professionals use specific imaging techniques to locate parathyroid glands. Ultrasound is often a first-line method for glands in the neck, using sound waves to visualize soft tissues. This technique can identify enlarged glands that are overactive.
For glands that are hyperactive or located in less accessible areas, nuclear medicine scans like the Sestamibi scan are employed. This procedure involves injecting a radioactive tracer, technetium-99m sestamibi, which is absorbed by overactive parathyroid tissue. A special camera then detects the radiation, highlighting the problematic gland, even if ectopic. If imaging methods are inconclusive, surgical exploration may be necessary to find the gland.
The Significance of Their Location
Knowing the precise location of parathyroid glands is important for diagnosing and treating parathyroid disorders. For example, in primary hyperparathyroidism, overactive glands lead to elevated blood calcium levels. Accurately locating the problematic gland is crucial for effective treatment.
The small size and variable location make surgical removal, known as parathyroidectomy, a complex procedure. Surgeons rely on pre-operative imaging and their understanding of anatomical variations to precisely target the affected gland while preserving surrounding tissues. This precision ensures successful treatment outcomes and minimizes complications.