Parathyroid adenoma

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Parathyroid adenoma
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Parathyroid adenoma
Specialty Endocrinology, Otolaryngology

A parathyroid adenoma is a benign tumor of the parathyroid gland. It generally causes hyperparathyroidism; there are very few reports of parathyroid adenomas that were not associated with hyperparathyroidism. [1]

Contents

A human being usually has four parathyroid glands located on the posterior surface of the thyroid in the neck. In order to maintain calcium metabolism, the parathyroid glands secrete parathyroid hormone (PTH) which stimulates the bones to release calcium and the kidneys to reabsorb it from the urine into the blood, thereby increasing its serum level. The action of calcitonin opposes PTH. When a parathyroid adenoma causes hyperparathyroidism, more parathyroid hormone is secreted, causing the calcium concentration of the blood to rise, resulting in hypercalcemia. [2]

Signs and symptoms

The first signs of a parathyroid adenoma and the resulting primary hyperparathyroidism can include bone fractures and urinary calculi such as kidney stones. [1]

Often, a parathyroid adenoma is diagnosed by an incidental finding on blood tests that reveal high calcium levels. [3] Patients may not be experiencing any noticeable symptoms but could be producing excessive amounts of calcium and eventually experience problems later in life if untreated. However, if symptomatic, patients can experience: pain or discomfort in the joints, muscles, and abdomen; depression and mood changes due to the hormonal imbalance.; [4] constipation; exhaustion; and kidney damage. [4]

Genetics

Parathyroid adenoma can be associated with overexpression of the cyclin D1 gene. [5] It is also associated with multiple endocrine neoplasia (MEN). [6]

Diagnosis

Micrograph of a parathyroid adenoma (left) and normal parathyroid gland (right). H&E stain. Parathyroid adenoma low mag.jpg
Micrograph of a parathyroid adenoma (left) and normal parathyroid gland (right). H&E stain.

Hyperparathyroidism is confirmed by blood tests such as calcium and PTH levels. A specific test for parathyroid adenoma is sestamibi parathyroid scintigraphy, the sestamibi scan. This nuclear imaging technique reveals the presence and location of pathological parathyroid tissue. [7]

4DCT is used as second line investigation to diagnose parathyroid adenoma. In addition to the three dimensional imaging of a conventional CT scan, 4DCT provides imaging on the changes of iodinated contrast enhancement over time and present them in a video format (from plain imaging to arterial to venous and delay phases). Parathyroid adenoma would show low density on non contrast image, with peak enhancement during the arterial phase, then slowly fade away until the delay phase. [8]

Treatment

Surgery is the only cure for parathyroid adenomas. [9] It is successful about 95% of the time. Parathyroidectomy is the removal of the affected gland(s). The standard of treatment of primary hyperparathyroidism was formerly a surgical technique called bilateral neck exploration, in which the neck was opened on both sides, the parathyroids were identified, and the affected tissue was removed. [10] By the 1980s, unilateral exploration became more common. [10] Parathyroidectomy can now be performed in a minimally invasive fashion, mainly because imaging techniques can pinpoint the location of the tissue. [10] Minimally invasive techniques include smaller open procedures, radio-guided and video-assisted procedures, and totally endoscopic surgery. [10]

Before surgery is attempted, the affected glandular tissue must be located. Though the parathyroid glands are usually located on the back of the thyroid, their position is variable. Some people have one or more parathyroid glands elsewhere in the neck anatomy or in the chest. About 10% of parathyroid adenomas are ectopic, located not along the back of the thyroid but elsewhere in the body, sometimes in the mediastinum of the chest. [9] This can make them difficult to locate, so various imaging techniques are used, such as the sestamibi scan, single-photon emission computed tomography (SPECT), ultrasound, MRI, [9] and CT scans. [9] [11] sometimes parathyroid adenomas can be ablated by ethanol injection, laser or radiofrequency guided by ultrasound.

Micrographs

See also

Related Research Articles

<span class="mw-page-title-main">Parathyroid gland</span> Endocrine gland

Parathyroid glands are small endocrine glands in the neck of humans and other tetrapods. Humans usually have four parathyroid glands, located on the back of the thyroid gland in variable locations. The parathyroid gland produces and secretes parathyroid hormone in response to a low blood calcium, which plays a key role in regulating the amount of calcium in the blood and within the bones.

<span class="mw-page-title-main">Parathyroid hormone</span> Mammalian protein found in Homo sapiens

Parathyroid hormone (PTH), also called parathormone or parathyrin, is a peptide hormone secreted by the parathyroid glands that regulates the serum calcium concentration through its effects on bone, kidney, and intestine.

Hypercalcemia, also spelled hypercalcaemia, is a high calcium (Ca2+) level in the blood serum. The normal range is 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcemia. Those with a mild increase that has developed slowly typically have no symptoms. In those with greater levels or rapid onset, symptoms may include abdominal pain, bone pain, confusion, depression, weakness, kidney stones or an abnormal heart rhythm including cardiac arrest.

<span class="mw-page-title-main">Parathyroid chief cell</span>

Parathyroid chief cells are one of the two cell types of the parathyroid glands, along with oxyphil cells. The chief cells are much more prevalent in the parathyroid gland than the oxyphil cells. It is perceived that oxyphil cells may be derived from chief cells at puberty, as they are not present at birth like chief cells.

Hypoparathyroidism is decreased function of the parathyroid glands with underproduction of parathyroid hormone (PTH). This can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany, and several other symptoms. It is a very rare disease. The condition can be inherited, but it is also encountered after thyroid or parathyroid gland surgery, and it can be caused by immune system-related damage as well as a number of rarer causes. The diagnosis is made with blood tests, and other investigations such as genetic testing depending on the results. The primary treatment of hypoparathyroidism is calcium and vitamin D supplementation. Calcium replacement or vitamin D can ameliorate the symptoms but can increase the risk of kidney stones and chronic kidney disease. Additionally, medications such as recombinant human parathyroid hormone or teriparatide may be given by injection to replace the missing hormone.

<span class="mw-page-title-main">Hyperparathyroidism</span> Increase in parathyroid hormone levels in the blood

Hyperparathyroidism is an increase in parathyroid hormone (PTH) levels in the blood. This occurs from a disorder either within the parathyroid glands or as response to external stimuli. Symptoms of hyperparathyroidism are caused by inappropriately normal or elevated blood calcium excreted from the bones and flowing into the blood stream in response to increased production of parathyroid hormone. In healthy people, when blood calcium levels are high, parathyroid hormone levels should be low. With long-standing hyperparathyroidism, the most common symptom is kidney stones. Other symptoms may include bone pain, weakness, depression, confusion, and increased urination. Both primary and secondary may result in osteoporosis.

Technetium (<sup>99m</sup>Tc) sestamibi Pharmaceutical drug

Technetium (99mTc) sestamibi (INN) is a pharmaceutical agent used in nuclear medicine imaging. The drug is a coordination complex consisting of the radioisotope technetium-99m bound to six (sesta=6) methoxyisobutylisonitrile (MIBI) ligands. The anion is not defined. The generic drug became available late September 2008. A scan of a patient using MIBI is commonly known as a "MIBI scan".

<span class="mw-page-title-main">Parathyroidectomy</span> Surgical removal of one or more of the parathyroid glands

Parathyroidectomy is the surgical removal of one or more of the (usually) four parathyroid glands. This procedure is used to remove an adenoma or hyperplasia of these glands when they are producing excessive parathyroid hormone (PTH): hyperparathyroidism. The glands are usually four in number and located adjacent to the posterior surface of the thyroid gland, but their exact location is variable. When an elevated PTH level is found, a sestamibi scan or an ultrasound may be performed in order to confirm the presence and location of abnormal parathyroid tissue.

<span class="mw-page-title-main">Endocrine gland</span> Glands of the endocrine system that secrete hormones to blood

Endocrine glands are ductless glands of the endocrine system that secrete their products, hormones, directly into the blood. The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testicles, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. The hypothalamus and pituitary glands are neuroendocrine organs.

<span class="mw-page-title-main">Primary hyperparathyroidism</span> Medical condition

Primary hyperparathyroidism is a medical condition where the parathyroid gland produce excess amounts of parathyroid hormone (PTH). The symptoms of the condition relate to the resulting elevated serum calcium (hypercalcemia), which can cause digestive symptoms, kidney stones, psychiatric abnormalities, and bone disease.

<span class="mw-page-title-main">Multiple endocrine neoplasia type 1</span> Medical condition

Multiple endocrine neoplasia type 1 (MEN-1) is one of a group of disorders, the multiple endocrine neoplasias, that affect the endocrine system through development of neoplastic lesions in pituitary, parathyroid gland and pancreas. Individuals suffering from this disorder are prone to developing multiple endocrine and nonendocrine tumors. It was first described by Paul Wermer in 1954.

<span class="mw-page-title-main">Osteitis fibrosa cystica</span> Medical condition

Osteitis fibrosa cystica is a skeletal disorder resulting in a loss of bone mass, a weakening of the bones as their calcified supporting structures are replaced with fibrous tissue, and the formation of cyst-like brown tumors in and around the bone. Osteitis fibrosis cystica (OFC), also known as osteitis fibrosa, osteodystrophia fibrosa, and von Recklinghausen's disease of bone, is caused by hyperparathyroidism, which is a surplus of parathyroid hormone from over-active parathyroid glands. This surplus stimulates the activity of osteoclasts, cells that break down bone, in a process known as osteoclastic bone resorption. The hyperparathyroidism can be triggered by a parathyroid adenoma, hereditary factors, parathyroid carcinoma, or renal osteodystrophy. Osteoclastic bone resorption releases minerals, including calcium, from the bone into the bloodstream, causing both elevated blood calcium levels, and the structural changes which weaken the bone. The symptoms of the disease are the consequences of both the general softening of the bones and the excess calcium in the blood, and include bone fractures, kidney stones, nausea, moth-eaten appearance in the bones, appetite loss, and weight loss.

<span class="mw-page-title-main">Secondary hyperparathyroidism</span> Medical condition

Secondary hyperparathyroidism is the medical condition of excessive secretion of parathyroid hormone (PTH) by the parathyroid glands in response to hypocalcemia, with resultant hyperplasia of these glands. This disorder is primarily seen in patients with chronic kidney failure. It is sometimes abbreviated "SHPT" in medical literature.

<span class="mw-page-title-main">Tertiary hyperparathyroidism</span> Medical condition

Tertiary hyperparathyroidism is a condition involving the overproduction of the hormone, parathyroid hormone, produced by the parathyroid glands. The parathyroid glands are involved in monitoring and regulating blood calcium levels and respond by either producing or ceasing to produce parathyroid hormone. Anatomically, these glands are located in the neck, para-lateral to the thyroid gland, which does not have any influence in the production of parathyroid hormone. Parathyroid hormone is released by the parathyroid glands in response to low blood calcium circulation. Persistent low levels of circulating calcium are thought to be the catalyst in the progressive development of adenoma, in the parathyroid glands resulting in primary hyperparathyroidism. While primary hyperparathyroidism is the most common form of this condition, secondary and tertiary are thought to result due to chronic kidney disease (CKD). Estimates of CKD prevalence in the global community range from 11 to 13% which translate to a large portion of the global population at risk of developing tertiary hyperparathyroidism. Tertiary hyperparathyroidism was first described in the late 1960s and had been misdiagnosed as primary prior to this. Unlike primary hyperparathyroidism, the tertiary form presents as a progressive stage of resolved secondary hyperparathyroidism with biochemical hallmarks that include elevated calcium ion levels in the blood, hypercalcemia, along with autonomous production of parathyroid hormone and adenoma in all four parathyroid glands. Upon diagnosis treatment of tertiary hyperparathyroidism usually leads to a surgical intervention.

<span class="mw-page-title-main">Endocrine disease</span> Medical condition

Endocrine diseases are disorders of the endocrine system. The branch of medicine associated with endocrine disorders is known as endocrinology.

<span class="mw-page-title-main">Parathyroid carcinoma</span> Medical condition

Parathyroid carcinoma is a rare cancer resulting in parathyroid adenoma to carcinoma progression. It forms in tissues of one or more of the parathyroid glands.

<span class="mw-page-title-main">Parathyroid disease</span> Medical condition

Many conditions are associated with disorders of the function of the parathyroid gland. Some disorders may be purely anatomical resulting in an enlarged gland which will raise concern. Such benign disorders, such as parathyroid cyst, are not discussed here. Parathyroid diseases can be divided into those causing hyperparathyroidism, and those causing hypoparathyroidism.

A calcimimetic is a pharmaceutical drug that mimics the action of calcium on tissues, by allosteric activation of the calcium-sensing receptor that is expressed in various human organ tissues. Calcimimetics are used to treat secondary hyperparathyroidism (SHPT).

<span class="mw-page-title-main">Sestamibi parathyroid scan</span> Procedure in nuclear medicine

A sestamibi parathyroid scan is a procedure in nuclear medicine which is performed to localize parathyroid adenoma, which causes Hyperparathyroidism. Adequate localization of parathyroid adenoma allows the surgeon to use a minimally invasive surgical approach.

In CT scan of the thyroid, focal and diffuse thyroid abnormalities are commonly encountered. These findings can often lead to a diagnostic dilemma, as the CT reflects nonspecific appearances. Ultrasound (US) examination has a superior spatial resolution and is considered the modality of choice for thyroid evaluation. Nevertheless, CT detects incidental thyroid nodules (ITNs) and plays an important role in the evaluation of thyroid cancer.

References

  1. 1 2 Sekine O, Hozumi Y, Takemoto N, Kiyozaki H, Yamada S, Konishi F (March 2004). "Parathyroid adenoma without hyperparathyroidism". Japanese Journal of Clinical Oncology. 34 (3): 155–8. doi: 10.1093/jjco/hyh028 . PMID   15078912.
  2. ↑ Felsenfeld AJ, Rodríguez M, Aguilera-Tejero E (November 2007). "Dynamics of parathyroid hormone secretion in health and secondary hyperparathyroidism". Clinical Journal of the American Society of Nephrology. 2 (6): 1283–305. doi: 10.2215/CJN.01520407 . PMID   17942777.
  3. ↑ (2012) The New York Times, Health Guide[ verification needed ]
  4. 1 2 "Parathyroid adenoma: Diagnosis & treatment". Cleveland Clinic. June 11, 2012.
  5. ↑ Hsi ED, Zukerberg LR, Yang WI, Arnold A (May 1996). "Cyclin D1/PRAD1 expression in parathyroid adenomas: an immunohistochemical study". The Journal of Clinical Endocrinology and Metabolism. 81 (5): 1736–9. doi: 10.1210/jcem.81.5.8626826 . PMID   8626826.
  6. ↑ "Multiple Endocrine Neoplasia". The Lecturio Medical Concept Library. Retrieved 11 August 2021.
  7. ↑ Goldstein RE, Billheimer D, Martin WH, Richards K (May 2003). "Sestamibi scanning and minimally invasive radioguided parathyroidectomy without intraoperative parathyroid hormone measurement". Annals of Surgery. 237 (5): 722–30, discussion 730–1. doi:10.1097/01.SLA.0000064362.58751.59. PMC   1514518 . PMID   12724639.
  8. ↑ Hoang, Jenny K.; Sung, Won-kyung; Bahl, Manisha; Phillips, C. Douglas (January 2014). "How to Perform Parathyroid 4D CT: Tips and Traps for Technique and Interpretation". Radiology. 270 (1): 15–24. doi:10.1148/radiol.13122661. ISSN   0033-8419. PMID   24354373.
  9. 1 2 3 4 Dsouza, Caren; Gopalakrishnan; Bhagavan, KR; Rakesh, K (2012). "Ectopic parathyroid adenoma". Thyroid Research and Practice. 9 (2): 68–70. doi: 10.4103/0973-0354.96061 .
  10. 1 2 3 4 Bellantone R, Raffaelli M, DE Crea C, Traini E, Lombardi CP (August 2011). "Minimally-invasive parathyroid surgery". Acta Otorhinolaryngologica Italica. 31 (4): 207–15. PMC   3203720 . PMID   22065831.
  11. ↑ Zald PB, Hamilton BE, Larsen ML, Cohen JI (August 2008). "The role of computed tomography for localization of parathyroid adenomas". The Laryngoscope. 118 (8): 1405–10. doi:10.1097/MLG.0b013e318177098c. PMID   18528308. S2CID   46264400.
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