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).

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.

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.

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.

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.

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.

Bone and joint pain are common, as are limb deformities. The elevated PTH has also pleiotropic effects on the blood, immune system, and neurological system.

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

In contrast with primary hyperparathyroidism in adults, primary hyperparathyroidism in pediatric patients is considered a rare endocrinopathy. Pediatric primary hyperparathyroidism can be distinguished by its more severe manifestations, in contrast to the less intense manifestations in adult primary hyperparathyroidism. Multiple endocrine neoplasia is more likely to be associated with childhood and adolescent primary hyperparathyroidism. The fundamental skeletal radiologic manifestation include diffuse osteopenia, pathologic fractures and the coexistence of resorption and sclerosis at numerous sites. Skeletal lesions can be specifically bilateral, symmetric and multifocal, exhibiting different types of bone resorption. Pathologic fractures of the femoral neck and spine can potentially initiate serious complications. Because pediatric primary hyperparathyroidism is frequently associated with pathologic fractures it can be misdiagnosed as osteogenesis imperfecta. Pediatric patients with primary hyperparathyroidism are best remedied by parathyroidectomy. Early diagnosis of pediatric primary hyperparathyroidism is all-important to minimize disease complications and start off timely and relevant treatment.

Secondary hyperparathyroidism (SHPT) refers to the excessive secretion of parathyroid hormone (PTH) by the parathyroid glands in response to hypocalcemia (low blood calcium levels) and associated hyperplasia of the glands. This disorder is especially seen in patients with chronic kidney failure. It is often—although not consistently—abbreviated as SHPT in medical literature.

Hypercalcemia is suspected to occur in approximately 1 in 500 adults in the general adult population. Like hypocalcemia, hypercalcemia can be non-severe and present with no symptoms, or it may be severe, with life-threatening symptoms. Hypercalcemia is most commonly caused by hyperparathyroidism and by malignancy, and less commonly by vitamin D intoxication, familial hypocalciuric hypercalcemia and by sarcoidosis. Hyperparathyroidism occurs most commonly in postmenopausal women. Hyperparathyroidism can be caused by a tumor, or adenoma, in the parathyroid gland or by increased levels of parathyroid hormone due to hypocalcemia. Approximately 10% of cancer sufferers experience hypercalcemia due to malignancy. Hypercalcemia occurs most commonly in breast cancer, lymphoma, prostate cancer, thyroid cancer, lung cancer, myeloma, and colon cancer. It may be caused by secretion of parathyroid hormone-related peptide by the tumor (which has the same action as parathyroid hormone), or may be a result of direct invasion of the bone, causing calcium release.

Symptoms of hypercalcemia include anorexia, nausea, vomiting, constipation, abdominal pain, lethargy, depression, confusion, polyuria, polydipsia and generalized aches and pains.

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.

Hypocalcemia is common and can occur unnoticed with no symptoms or, in severe cases, can have dramatic symptoms and be life-threatening. Hypocalcemia can be parathyroid related or vitamin D related. Parathyroid related hypocalcemia includes post-surgical hypoparathyroidism, inherited hypoparathyroidism, pseudohypoparathyroidism, and pseudo-pseudohypoparathyroidism. Post-surgical hypoparathyroidism is the most common form, and can be temporary (due to suppression of tissue after removal of a malfunctioning gland) or permanent, if all parathyroid tissue has been removed. Inherited hypoparathyroidism is rare and is due to a mutation in the calcium sensing receptor. Pseudohypoparathyroidism is maternally inherited and is categorized by hypocalcemia and hyperphosphatemia. Finally, pseudo-pseudohypoparathyroidism is paternally inherited. Patients display normal parathyroid hormone action in the kidney, but exhibit altered parathyroid hormone action in the bone.

Vitamin D related hypocalcemia may be associated with a lack of vitamin D in the diet, a lack of sufficient UV exposure, or disturbances in renal function. Low vitamin D in the body can lead to a lack of calcium absorption and secondary hyperparathyroidism (hypocalcemia and raised parathyroid hormone). Symptoms of hypocalcemia include numbness in fingers and toes, muscle cramps, irritability, impaired mental capacity and muscle twitching.

Pseudopseudohypoparathyroidism can be best understood by comparing it to other conditions:

Hormone resistance is not present in pseudopseudohypoparathyroidism. Short stature may be present. Obesity is less common in pseudopseudohypoparathyroidism than in pseudohypoparathyroidism. Osteoma cutis may be present.

Diagnosis typically occurs during the first 6 months of life due to characteristic neurological symptoms. These symptoms include muscle spasms, tetany, and seizures. Laboratory testing indicates hypomagnesemia (decreased serum magnesium levels), hypocalcemia (decreased serum calcium levels), and little to no measurable parathyroid hormone levels. Diagnosis is confirmed with these symptoms and can be further solidified with genetic sequencing of the TRPM6 gene.

The major symptoms of OFC are bone pain or tenderness, bone fractures, and skeletal deformities such as bowing of the bones. The underlying hyperparathyroidism may cause kidney stones, nausea, constipation, fatigue and weakness. X-rays may indicate thin bones, fractures, bowing, and cysts. Fractures are most commonly localized in the arms, legs, or spine.

The addition of weight loss, appetite loss, vomiting, polyuria, and polydipsia to the aforementioned symptoms may indicate that OFC is the result of parathyroid carcinoma. Parathyroid carcinoma, an uncommon cancer of the parathyroid glands, is generally indicated by serum calcium levels higher than usual, even in comparison to the high serum calcium levels that OFC generally presents with. Symptoms are also often more severe. Generally, the presence of a palpable neck mass is also indicative of the cancer, occurring in approximately 50% of sufferers, but virtually nonexistent in individuals with OFC with a different origin.

The disorder is characterized by the following:

Individuals with Albright hereditary osteodystrophy exhibit short stature, characteristically shortened fourth and fifth metacarpals, rounded facies, and often mild intellectual deficiency. Albright hereditary osteodystrophy is commonly known as pseudohypoparathyroidism because the kidney responds as if parathyroid hormone were absent. Blood levels of parathyroid hormone are elevated in pseudohypoparathyroidism due to the hypocalcemia

Osteitis fibrosa cystica is defined as the classic skeletal manifestation of advanced hyperparathyroidism. Under the ICD-10 classification system, established by the World Health Organization, OFC is listed under category E21.0, primary hyperparathyroidism.

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.

Hypomagnesemia with secondary hypocalcemia (HSH) is an autosomal recessive genetic disorder affecting intestinal magnesium absorption. Decreased intestinal magnesium reabsorption and the resulting decrease in serum magnesium levels is believed to cause lowered parathyroid hormone (PTH) output by the parathyroid gland. This results in decreased PTH and decreased serum calcium levels (hypocalcemia). This manifests in convulsions and spasms in early infancy which, if left untreated, can lead to mental retardation or death. HSH is caused by mutations in the TRPM6 gene.

Pseudopseudohypoparathyroidism (PPHP) is an inherited disorder, named for its similarity to pseudohypoparathyroidism in presentation. It is more properly Albright hereditary osteodystrophy although without resistance of parathyroid hormone frequently seen in that affliction. The term pseudopseudohypoparathyroidism is used to describe a condition where the individual has the phenotypic appearance of pseudohypoparathyroidism type 1a, but has (unexpected for the phenotype) normal labs including Calcium and PTH.

It can be considered a variant of Albright hereditary osteodystrophy, or pseudohypoparathyroidism type 1A, as they present with the same constellation of signs and symptoms, including short stature, brachydactyly, subcutaneous calcification, and obesity.

Albright's hereditary osteodystrophy is a form of osteodystrophy, and is classified as the phenotype of pseudohypoparathyroidism type 1A; this is a condition in which the body does not respond to parathyroid hormone.

Blood levels of parathryoid hormone (PTH) are undetectable, but the mutation in the PTHR1 leads to auto-activation of the signaling as though the hormone PTH is present. Severe JMC produces a dwarfing phenotype, or short stature. Examination of the bone reveals normal epiphyseal plates but disorganized metaphyseal regions. Hypercalcemia (elevated levels of calcium in the blood) and hypophosphatemia (reduced blood levels of phosphate), and elevated urinary calcium and phosphate are generally found in JMC. The absence of hypercalcemia does not eliminate the disease from consideration.

Physical irregularities often associated with Jansen's include: prominent or protruding eyes, a high-arched palate, micrognathia or abnormal smallness of the jaws – particularly the lower (mandible) jaw, choanal stenosis, wide cranial sutures and irregular formation of the long bones which can resemble rickets. Nephrocalcinosis (accumulation of calcium in the interstitum of the kidney) is seen commonly as well.

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 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.