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

Oftentimes parathyroid adenoma is not diagnosed until found on standard blood-tests that reveal high calcium content in the blood, it can appear in urine tests as well. 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, patients can experience common symptoms that can range from joint, muscle, and abdominal pain to slight discomfort. Additionally patients might be experiencing feelings of depression due to the hormonal imbalance. Constipation and exhaustion can also be experienced as a result of the irregularity in the bloodstream. There is also a potential that the kidneys could be damaged with the excess of calcium in the blood.

The signs and symptoms of primary hyperparathyroidism are those of hypercalcemia. They are classically summarized by "stones, bones, abdominal groans, thrones and psychiatric overtones".

- "Stones" refers to kidney stones, nephrocalcinosis, and diabetes insipidus (polyuria and polydipsia). These can ultimately lead to renal failure.

- "Bones" refers to bone-related complications. The classic bone disease in hyperparathyroidism is osteitis fibrosa cystica, which results in pain and sometimes pathological fractures. Other bone diseases associated with hyperparathyroidism are osteoporosis, osteomalacia, and arthritis.

- "Abdominal groans" refers to gastrointestinal symptoms of constipation, indigestion, nausea and vomiting. Hypercalcemia can lead to peptic ulcers and acute pancreatitis. The peptic ulcers can be an effect of increased gastric acid secretion by hypercalcemia.

- "Thrones" refers to polyuria and constipation

- "Psychiatric overtones" refers to effects on the central nervous system. Symptoms include lethargy, fatigue, depression, memory loss, psychosis, ataxia, delirium, and coma.

Left ventricular hypertrophy may also be seen.

Other signs include proximal muscle weakness, itching, and band keratopathy of the eyes.

When subjected to formal research, symptoms of depression, pain, and gastric dysfunction seem to correlate with mild cases of hypercalcemia.

The main symptoms of hypoparathyroidism are the result of the low blood calcium level, which interferes with normal muscle contraction and nerve conduction. As a result, people with hypoparathyroidism can experience paresthesia, an unpleasant tingling sensation around the mouth and in the hands and feet, as well as muscle cramps and severe spasms known as "tetany" that affect the hands and feet. Many also report a number of subjective symptoms such as fatigue, headaches, bone pain and insomnia. Crampy abdominal pain may occur. Physical examination of someone with hypocalcemia may show tetany, but it is also possible to provoke tetany of the facial muscles by tapping on the facial nerve (a phenomenon known as Chvostek's sign) or by using the cuff of a sphygmomanometer to temporarily obstruct the blood flow to the arm (a phenomenon known as Trousseau's sign of latent tetany).

A number of medical emergencies can arise in people with low calcium levels. These are seizures, severe irregularities in the normal heart beat, as well as spasm of the upper part of the airways or the smaller airways known as the bronchi (both potentially causing respiratory failure).

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.

A human being usually has four parathyroid glands located on the back surface of the thyroid in the neck. The parathyroids secrete parathyroid hormone (PTH), which increases the concentration of calcium in the blood by inducing the bones to release calcium into the blood and the kidneys to reabsorb it from the urine into the blood. When a parathyroid adenoma causes hyperparathyroidism, more parathyroid hormone is secreted, causing the calcium concentration of the blood to rise, resulting in hypercalcemia.

Primary hyperparathyroidism is usually caused by a tumor within the parathyroid gland. The symptoms of the condition relate to the elevated calcium levels, which can cause digestive symptoms, kidney stones, psychiatric abnormalities, and bone disease.

The diagnosis is initially made on blood tests; an elevated level of calcium together with a raised level of parathyroid hormone are typically found. To identify the source of the excessive hormone secretion, medical imaging may be performed. Parathyroidectomy, the surgical removal of one or more parathyroid glands, may be required to control symptoms.

Hypoparathyroidism is decreased function of the parathyroid glands with underproduction of parathyroid hormone. This can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany (involuntary muscle contraction), and several other symptoms. 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 treatment of hypoparathyroidism is limited by the fact that there is no exact form of the hormone that can be administered as replacement. However teriparatide, brand name Forteo, a biosimilar peptide to parathyroid hormone, may be given by injection. Calcium replacement or vitamin D can ameliorate the symptoms but can increase the risk of kidney stones and chronic kidney disease.

Symptoms depend on whether the hyperparathyroidism is the result of parathyroid overactivity or secondary.

In primary hyperparathyroidism about 75% of people have no symptoms. The problem is often picked up during blood work for other reasons via a raised calcium. Many other people only have non-specific symptoms. Symptoms directly due to hypercalcemia are relatively rare, being more common in patients with malignant hypercalcemia. If present, common manifestations of hypercalcemia include weakness and fatigue, depression, bone pain, muscle soreness (myalgias), decreased appetite, feelings of nausea and vomiting, constipation, polyuria, polydipsia, cognitive impairment, kidney stones (See Foot Note) and osteoporosis. A history of acquired racquet nails (brachyonychia) may be indicative of bone resorption. Parathyroid adenomas are very rarely detectable on clinical examination. Surgical removal of a parathyroid tumor eliminates the symptoms in most patients.

In secondary hyperparathyroidism the parathyroid gland is behaving normally; clinical problems are due to bone resorption and manifest as bone syndromes such as rickets, osteomalacia and renal osteodystrophy.

Many conditions are associated with disorders of the function of the parathyroid gland. Parathyroid diseases can be divided into those causing hyperparathyroidism, and those causing hypoparathyroidism.

Broadly speaking, endocrine disorders may be subdivided into three groups:

1. Endocrine gland hyposecretion (leading to hormone deficiency)

2. Endocrine gland hypersecretion (leading to hormone excess)

3. Tumours (benign or malignant) of endocrine glands

Endocrine disorders are often quite complex, involving a mixed picture of hyposecretion and hypersecretion because of the feedback mechanisms involved in the endocrine system. For example, most forms of hyperthyroidism are associated with an excess of thyroid hormone and a low level of thyroid stimulating hormone.

Tertiary hyperparathyroidism is a state of excessive secretion of parathyroid hormone (PTH) after a long period of secondary hyperparathyroidism and resulting in a high blood calcium level. It reflects development of autonomous (unregulated) parathyroid function following a period of persistent parathyroid stimulation.

The basis of treatment is still prevention in chronic kidney failure, starting medication and dietary restrictions long before dialysis treatment is initiated. Cinacalcet has greatly reduced the number of patients who ultimately require surgery for secondary hyperparathyroidism; however, approximately 5% of patients do not respond to medical therapy.

When secondary hyperparathyroidism is corrected and the parathyroid glands remain hyperfunctioning, it becomes tertiary hyperparathyroidism. The treatment of choice is surgical removal of three and one half parathyroid glands.

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

Hyperparathyroidism is an increased parathyroid hormone (PTH) levels in the blood. This occurs either from the parathyroid glands inappropriately making too much PTH (primary hyperparathyroidism) or other events triggering increased production by the parathyroid glands (secondary hyperparathyroidism). Most people with primary disease have no symptoms at the time of diagnosis. In those with symptoms the most common is kidney stones with other potential symptoms including weakness, depression, bone pains, confusion, and increased urination. Both types increase the risk of weak bones.

Primary hyperparathyroidism in 80% of cases is due to a single benign tumor known as a parathyroid adenoma with most of the rest of the cases due to a multiple benign tumors. Rarely it may be due to parathyroid cancer. Secondary hyperparathyroidism typically occurs due to vitamin D deficiency, chronic kidney disease, or other causes of low blood calcium. Diagnosis of primary disease is by finding a high blood calcium and high PTH levels.

Primary hyperparathyroidism may be cured by removing the adenoma or overactive parathyroid glands. In those without symptoms, mildly increased blood calcium levels, normal kidneys, and normal bone density monitoring may be all that is required. The medication cinacalcet may also be used to decrease PTH levels. In those with very high blood calcium levels treatment may include large amounts of intravenous normal saline. Low vitamin D levels should be corrected.

Primary hyperparathyroidism is the most common form. In the developed world between one and four per thousand people are affected. It occurs three times more often in women than men and is typically diagnosed between the ages of 50 and 60. The disease was first described in the 1700s and in the late 1800s was determined to be related to the parathyroid. Surgery as a treatment was first carried out in 1925.

Hyperplasia is considered to be a physiological (normal) response to a specific stimulus, and the cells of a hyperplastic growth remain subject to normal regulatory control mechanisms. However, hyperplasia can also occur as a pathological response, if an excess of hormone or growth factor is responsible for the stimuli. Similarly to physiological hyperplasia, cells that undergo pathologic hyperplasia are controlled by growth hormones, and cease to proliferate if such stimuli are removed. This differs from neoplasia (the process underlying cancer and benign tumors), in which genetically abnormal cells manage to proliferate in a non-physiological manner which is unresponsive to normal stimuli. That being said, the effects caused by pathologic hyperplasia can provide a suitable foundation from which neoplastic cells may develop.

Hyperplasia (from ancient Greek ὑπέρ "huper", "over" + πλάσις "plasis", "formation"), or hypergenesis, is an increase in the amount of organic tissue that results from cell proliferation. It may lead to the gross enlargement of an organ and the term is sometimes confused with benign neoplasia or benign tumor.

Hyperplasia is a common preneoplastic response to stimulus. Microscopically, cells resemble normal cells but are increased in numbers. Sometimes cells may also be increased in size (hypertrophy). Hyperplasia is different from hypertrophy in that the adaptive cell change in hypertrophy is an increase in the "size" of cells, whereas hyperplasia involves an increase in the "number" of cells.

The single major disease of parathyroid glands is overactivity of one or more of the parathyroid lobes, which make too much parathyroid hormone, causing a potentially serious calcium imbalance. This is called hyperparathyroidism; it leads to hypercalcemia, kidney stones, osteoporosis, and various other symptoms. Hyperparathyroidism was first described in 1925 and the symptoms have collectively become known as "moans, groans, stones, and bones." By far, the most common symptom is fatigue, but depression, memory loss, and bone aches are also very common. Primary hyperparathyroidism is relatively more common in postmenopausal women. The primary treatment for this disease is the surgical removal of the faulty gland.

If a patient has elevated calcium, several different types of tests can be used to locate the abnormal glands. The most common and most accurate test to find a parathyroid tumor is the Sestamibi scan. The Sestamibi scan does not have high resolution. Neck ultrasound has higher resolution, but requires some expertise to perform. Ultrasound's shortcomings include: it cannot determine glandular function (normal vs. hyperfunctioning) or visualize unusual locations such as retropharyngeal or mediastinal. Thin cut computed tomography of the neck can reveal glands in locations that the ultrasound cannot evaluate well; e.g. retropharyngeal, mediastinal. These tests are ordered by an endocrinologist or a surgeon that specializes in parathyroid surgery. Often, these "localizing" tests used to "find" the bad parathyroid gland are not successful in locating which parathyroid gland has become a tumor. This often causes confusion for the patient and doctor, since the tumor was not located. This simply means that the tumor was not found using these tests; it does not mean the tumor does not exist. The use of ultrasound-guided FNA, and parathyroid hormone washings can confirm the abnormal glands. For decades, it has been known that the best way to find a parathyroid tumor is through a very experienced parathyroid surgeon.

Even if a patient has a non-localizing Sestamibi scan (a negative sestamibi scan), he/she should almost always have a neck exploration to remove the tumor if he/she has high calcium levels, among other symptoms. Minimally-invasive parathyroid surgery is becoming more available, but, depending on the expertise of the surgeon, the patient may need to have a positive sestamibi scan before a minimally-invasive operation is attempted. Some of the most experienced surgeons perform mini-parathyroid surgery on all patients, but this is available only at highly specialized centers. Some patients will need both sides of their necks explored to find the dysfunctional gland(s).

Another related condition is called secondary hyperparathyroidism (HPT for short), which is common in patients with chronic kidney disease on dialysis. In secondary HPT, the parathyroid glands make too much parathyroid hormone (PTH) because the kidneys have failed, and the calcium and phosphorus are out of balance. Even though one may not have any symptoms, treating secondary HPT is important. Cinacalcet (Sensipar) is a medicine that can help treat such dialysis patients and is available by prescription only. Most experts believe that Sensipar should not be used for patients with primary hyperparathyroidism (patients that have a high calcium and are not on kidney dialysis).

Parathyroid surgery is usually performed when there is hyperparathyroidism. This condition causes many diseases related with calcium reabsorption, because the principal function of the parathyroid hormone is to regulate it. Parathyroid surgery could be performed in two different ways: first is a complete parathyroidectomy, and second is the auto transplantation of the removed parathyroid glands. There are various conditions that can indicate the need for the removal or transplant of the parathyroid glands. Hyperparathyroidism is a condition caused by overproduction of PTH, and can be divided into three types.

- Primary hyperparathyroidism happens when the normal mechanism of regulation by negative feedback of calcium is interrupted, or in other words the amount of blood calcium would ordinarily signal less production of PTH. Most of the time this is caused by adenomas, hyperplasia or carcinomas.

- Secondary hyperparathyroidism normally occurs in patients that suffer renal disease. Poor kidney function leads to a mineral disequilibrium that causes the glands hypertrophy in order to synthesize and release more PTH.

- Tertiary hyperparathyroidism develops when the hyperplastic gland of secondary hyperparathyroidism constantly releases PTH, independent of the regulation systems.

Another condition is hypercalcemia, which refers to a calcium level above 10.5 mg/dL. Consequences of this are heart rhythm diseases, and extra production of gastrin that causes peptic ulcers.

Parathyroid transplant is recommended if the parathyroid glands are removed accidentally during a thyroidectomy. They are autotransplanted to the nearby sternocleidomastoid muscle, or to the forearm so that another intervention would be less risky. A biopsy is recommended to be sure that the transplanted tissue is parathyroid and not a lymph node with metastatic disease. During parathyroid surgery if there is an adenoma the transplantation is not recommended; instead it is cryopreserved for research an if there is a recurrent hypoparathyroidism.

The surgery is indicated for all patients that are diagnosed with hyperparathyroidism with or without symptoms, especially in younger patients. In some cases the surgery works as therapy for nephrolithiasis, bone changes, and neuromuscular symptoms.

Mineralocorticoid manifestations of severe 11β-hydroxylase deficient CAH can be biphasic, changing from deficiency (salt-wasting) in early infancy to excess (hypertension) in childhood and adult life.

Salt-wasting in early infancy does not occur in most cases of 11β-OH CAH but can occur because of impaired production of aldosterone aggravated by inefficiency of salt conservation in early infancy. When it occurs it resembles the salt-wasting of severe 21-hydroxylase deficient CAH: poor weight gain and vomiting in the first weeks of life progress and culminate in life-threatening dehydration, hyponatremia, hyperkalemia, and metabolic acidosis in the first month.

Despite the inefficient production of aldosterone, the more characteristic mineralocorticoid effect of 11β-OH CAH is hypertension. Progressive adrenal hyperplasia due to persistent elevation of ACTH results in extreme overproduction of 11-deoxycorticosterone (DOC) by mid-childhood. DOC is a weak mineralocorticoid, but usually reaches high enough levels in this disease to cause effects of mineralocorticoid excess: salt retention, volume expansion, and hypertension.

Most patients experience moderate to severe hypercalcemia and high parathyroid hormone levels. A large mass in the neck is often seen, and renal and bone abnormalities are common.

Patients may present with features of hypocalcaemia including carpo-pedal muscular spasms, cramping, tetany, and if the calcium deficit is severe, generalized seizures. IQ is typically mildly depressed or unaffected. Additional characteristics include short stature, obesity, developmental delay, and calcification of the basal ganglia in the deep white matter of the brain.

Type 1a Pseudohypoparathyroidism is clinically manifest by bone resorption with blunting of the fourth and fifth knuckles of the hand, most notable when the dorsum of the hand is viewed in closed fist position. This presentation is known as 'knuckle knuckle dimple dimple' sign (Archibald's Sign). This is as opposed to Turner syndrome which is characterized by blunting of only the fourth knuckle, and Down's syndrome, which is associated with a hypoplastic middle phalanx.

Salivary gland hyperplasia is hyperplasia of the terminal duct of salivary glands.

There are two types:

- Acinar adenomatoid hyperplasia

- Ductal adenomatoid hyperplasia

A parathyroid neoplasm is a tumor of the parathyroid gland.

Types include:

- Parathyroid adenoma

- Parathyroid carcinoma

MEN2 can present with a sign or symptom related to a tumor or, in the case of multiple endocrine neoplasia type 2b, with characteristic musculoskeletal and/or lip and/or gastrointestinal findings.Medullary thyroid carcinoma (MTC) represent the most frequent initial diagnosis. Occasionally pheochromocytoma or primary hyperparathyroidism may be the initial diagnosis.

Pheochromocytoma occurs in 33-50% of MEN2 cases. In MEN2A, primary hyperparathyroidism occurs in 10–50% of cases and is usually diagnosed after the third decade of life. Rarely, it may present in childhood or be the sole clinical manifestation of this syndrome.

MEN2A associates medullary thyroid carcinoma with pheochromocytoma in about 20–50% of cases and with primary hyperparathyroidism in 5–20% of cases.MEN2B associates medullary thyroid carcinoma with pheochromocytoma in 50% of cases, with marfanoid habitus and with mucosal and digestive neurofibromatosis.

In familial isolated medullary thyroid carcinoma the other components of the disease are absent.

In a review of 85 patients 70 had Men2A and 15 had Men2B. The initial manifestation of MEN2 was medullary thyroid carcinoma in 60% of patients, medullary thyroid carcinoma synchronous with pheochromocytoma in 34% and pheochromocytoma alone in 6%. 72% had bilateral pheochromocytomas.

Thymus hyperplasia (or thymic hyperplasia) refers to an enlargement ("hyperplasia") of the thymus.

It is not always a disease state. The size of the thymus usually peaks during adolescence, and atrophies in the following decades. Before the immune function of the thymus was well understood, the enlargement was sometimes seen as a cause for alarm, and justification for surgical reduction. This approach is much less common today.

It can be associated with myasthenia gravis.

MRI can be used to distinguish it from thymoma.

Symptoms of the condition vary with type: hypo- vs. hyperthyroidism, which are further described below.

Possible symptoms of hypothyroidism are:

Possible symptoms of hyperthyroidism are:Note: certain symptoms and physical changes can be seen in both hypothyroidism and hyperthyroidism —fatigue, fine / thinning hair, menstrual cycle irregularities, muscle weakness / aches (myalgia), and different forms of myxedema.

Multiple endocrine neoplasia or MEN is part of a group of disorders that affect the body's network of hormone-producing glands (the endocrine system). Hormones are chemical messengers that travel through the bloodstream and regulate the function of cells and tissues throughout the body. Multiple endocrine neoplasia involves tumors in at least two endocrine glands; tumors can also develop in other organs and tissues. These growths can be noncancerous (benign) or cancerous (malignant). If the tumors become cancerous, some cases can be life-threatening.

The two major forms of multiple endocrine neoplasia are called type 1 and type 2. These two types are often confused because of their similar names. However, type 1 and type 2 are distinguished by the genes involved, the types of hormones made, and the characteristic signs and symptoms.

These disorders greatly increase the risk of developing multiple cancerous and noncancerous tumors in glands such as the parathyroid, pituitary, and pancreas. Multiple endocrine neoplasia occurs when tumors are found in at least two of the three main endocrine glands (parathyroid, pituitary, and pancreatico-duodenum). Tumors can also develop in organs and tissues other than endocrine glands. If the tumors become cancerous, some cases can be life-threatening. The disorder affects 1 in 30,000 people.

Although many different types of hormone-producing tumors are associated with multiple endocrine neoplasia, tumors of the parathyroid gland, pituitary gland, and pancreas are most frequent in multiple endocrine neoplasia type 1. MEN1-associated overactivity of these three endocrine organs are briefly described here:

- Overactivity of the parathyroid gland (hyperparathyroidism) is the most common sign of this disorder. Hyperparathyroidism disrupts the normal balance of calcium in the blood, which can lead to kidney stones, thinning of the bones (osteoporosis), high blood pressure (hypertension), loss of appetite, nausea, weakness, fatigue, and depression.

- Neoplasia in the pituitary gland can manifest as prolactinomas whereby too much prolactin is secreted, suppressing the release of gonadotropins, causing a decrease in sex hormones such as testosterone. Pituitary tumor in MEN1 can be large and cause signs by compressing adjacent tissues.

- Pancreatic tumors associated with MEN-1 usually form in the beta cells of the islets of Langerhans, causing over-secretion of insulin, resulting in low blood glucose levels (hypoglycemia). However, many other tumors of the pancreatic Islets of Langerhans can occur in MEN-1. One of these, involving the alpha cells, causes over-secretion of glucagon, resulting in a classic triad of high blood glucose levels (hyperglycemia), a rash called necrolytic migratory erythema, and weight loss. Another is a tumor of the non-beta islet cells, known as a gastrinoma, which causes the over-secretion of the hormone gastrin, resulting in the over-production of acid by the acid-producing cells of the stomach (parietal cells) and a constellation of sequelae known as Zollinger-Ellison syndrome. Zollinger-Ellison syndrome may include severe gastric ulcers, abdominal pain, loss of appetite, chronic diarrhea, malnutrition, and subsequent weight loss. Other non-beta islet cell tumors associated with MEN1 are discussed below.

The term pseudopseudohypoparathyroidism is used to describe a condition where the individual has the phenotypic appearance of pseudohypoparathyroidism type 1a, but is biochemically normal.