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 Tetany or tetanic seizure is a medical sign consisting of the involuntary contraction of muscles, which may be caused by disorders that increase the action potential frequency of muscle cells or the nerves that innervate them. Muscle cramps cau ...

(involuntary muscle contraction), and several other symptoms. It is a very rare disease. The condition can be inherited, but it is also encountered after

thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The ...

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 test A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose test or a choles ...

s, and other investigations such as

genetic testing Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...

depending on the results. The primary treatment of hypoparathyroidism is calcium and vitamin D supplementation. Calcium replacement or

vitamin D Vitamin D is a group of Lipophilicity, fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group ar ...

can ameliorate the symptoms but can increase the risk of kidney stones and

chronic kidney disease Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vo ...

. Additionally, injectable medications such as

recombinant human parathyroid hormone Recombinant human parathyroid hormone, sold under the brand names Preotact and Natpara, is an artificially manufactured form of the parathyroid hormone used to treat hypoparathyroidism. Recombinant human parathyroid hormone is used in the trea ...

or teriparatide may be given by injection to replace the missing hormone.

Signs and symptoms

The main symptoms of hypoparathyroidism are the result of the low blood calcium level, which interferes with normal

muscle contraction Muscle contraction is the activation of tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such a ...

and nerve conduction. As a result, people with hypoparathyroidism can experience

paresthesia Paresthesia is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. Paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias a ...

, an unpleasant tingling sensation around the mouth and in the hands and feet, as well as muscle cramps and severe spasms known as "

" that affect the hands and feet. Many also report a number of subjective symptoms such as

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

s, bone pain and

insomnia Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, ...

. Crampy

abdominal pain Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues. Common causes of pain in the abdomen include gastroenteritis and irritable bowel syndrome. About 15% of people have a m ...

may occur.

Physical examination In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the pati ...

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 The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste ...

(a phenomenon known as

Chvostek's sign The Chvostek sign () is a clinical sign that someone may have a low blood calcium level (a decreased serum calcium, called hypocalcemia). The Chvostek sign is the abnormal twitching of muscles that are activated (innervated) by the facial nerve ...

) 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 An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with lo ...

, 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 Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise ...

Related conditions

Causes

Hypoparathyroidism can have the following causes: * Removal of, or trauma to, the parathyroid glands due to

surgery ( thyroidectomy), parathyroid surgery (parathyroidectomy) or other surgical interventions in the central part of the neck (such as operations on the larynx and/or pharynx) is a recognized cause. It is the most common cause of hypoparathyroidism. Although

surgeon In modern medicine, a surgeon is a medical professional who performs surgery. Although there are different traditions in different times and places, a modern surgeon usually is also a licensed physician or received the same medical training as ...

s generally make attempts to spare normal parathyroid glands at surgery, inadvertent injury to the glands or their blood supply is still common. When this happens, the parathyroids may cease functioning. This is usually temporary but occasionally long term (permanent). * Kenny-Caffey Syndrome *

Autoimmune In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". ...

invasion and destruction is the most common non-surgical cause. It can occur as part of

autoimmune polyendocrine syndrome Autoimmune polyendocrine syndromes (APSs), also called polyglandular autoimmune syndromes (PGASs) or polyendocrine autoimmune syndromes (PASs), are a heterogeneous group of rare diseases characterized by autoimmune activity against more than one e ...

s. *

Hemochromatosis Iron overload or hemochromatosis (also spelled ''haemochromatosis'' in British English) indicates increased total accumulation of iron in the body from any cause and resulting organ damage. The most important causes are hereditary haemochromatosi ...

can lead to iron accumulation and consequent dysfunction of a number of endocrine organs, including the parathyroids. * Absence or dysfunction of the parathyroid glands is one of the components of chromosome 22q11 microdeletion syndrome (other names: DiGeorge syndrome, Schprintzen syndrome, velocardiofacial syndrome). * Magnesium deficiency * A defect in the calcium receptor leads to a rare congenital form of the disease * Idiopathic (of unknown cause) * Occasionally due to other hereditary causes (e.g. Barakat syndrome (HDR syndrome) a genetic development disorder resulting in hypoparathyroidism, sensorineural deafness, and kidney disease)

Mechanism

The parathyroid glands are so named because they are usually located behind the

thyroid gland The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...

in the neck. They arise during fetal development from structures known as the third and fourth pharyngeal pouch. The glands, usually four in number, contain the parathyroid chief cells that sense the level of

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...

in the blood through the calcium-sensing receptor and secrete parathyroid hormone.

Magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...

is required for PTH secretion. Under normal circumstances, the parathyroids secrete PTH to maintain a calcium level within normal limits, as calcium is required for adequate muscle and nerve function (including the

autonomic nervous system The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies internal organs, smooth muscle and glands. The autonomic nervous system is a control system t ...

). PTH acts on several organs to increase calcium levels. It increases calcium absorption in the bowel, while in the kidney it prevents calcium excretion and increases phosphate release and in bone it increases calcium through bone resorption.

Diagnosis

Diagnosis is by measurement of

, serum albumin (for correction) and PTH in

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

. If necessary, measuring

cAMP Camp may refer to: Outdoor accommodation and recreation * Campsite or campground, a recreational outdoor sleeping and eating site * a temporary settlement for nomads * Camp, a term used in New England, Northern Ontario and New Brunswick to descri ...

(cyclic AMP) in the urine after an intravenous dose of PTH can help in the distinction between hypoparathyroidism and other causes. Differential diagnoses are: * Pseudohypoparathyroidism (normal PTH levels but tissue insensitivity to the hormone, associated with

intellectual disability Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation, Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signif ...

and skeletal deformities) and pseudopseudohypoparathyroidism. * Vitamin D deficiency or hereditary insensitivity to this vitamin (X-linked dominant). * Malabsorption *

Kidney disease Kidney disease, or renal disease, technically referred to as nephropathy, is damage to or disease of a kidney. Nephritis is an inflammatory kidney disease and has several types according to the location of the inflammation. Inflammation can ...

* Medication:

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...

diuretic A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics i ...

s, some

antiepileptic Anticonvulsants (also known as antiepileptic drugs or recently as antiseizure drugs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of b ...

s. Other tests include ECG for abnormal heart rhythms, and measurement of blood magnesium levels.

Treatment

Severe hypocalcaemia, a potentially life-threatening condition, is treated as soon as possible with

intravenous Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrie ...

(e.g. as calcium gluconate). Generally, a central venous catheter is recommended, as the calcium can irritate

peripheral vein The peripheral vascular system is the part of the circulatory system that consists of the veins and arteries not in the chest or abdomen (i.e. in the arms, hands, legs and feet). The peripheral arteries supply oxygenated blood to the body, an ...

s and cause phlebitis. In the event of a life-threatening attack of low calcium levels or tetany (prolonged muscle contractions), calcium is administered by intravenous (IV) infusion. Precautions are taken to prevent seizures or larynx spasms. The heart is monitored for abnormal rhythms until the person is stable. When the life-threatening attack has been controlled, treatment continues with medicine taken by mouth as often as four times a day. Long-term treatment of hypoparathyroidism is with

analogs and calcium supplementation, but may be ineffective in some due to potential renal damage. The

N-terminal The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...

fragment of parathyroid hormone (PTH 1-34) has full

biological activity In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...

. The use of pump delivery of synthetic PTH 1-34 provides the closest approach to physiologic PTH replacement therapy. Injections of

are available as treatment in those with low blood calcium levels.

References

External links

{{Medicine Parathyroid disorders Endocrine-related cutaneous conditions Rare diseases