is decreased function of the parathyroid glands
, leading to decreased levels of parathyroid hormone
(PTH). The consequence, hypocalcemia
, is a serious medical condition.
Signs and symptoms
- Tingling lips, fingers, and toes
- Muscle cramps
- Pain in the face, legs, and feet
- Abdominal pain
- Dry hair
- Brittle nails
- Dry, scaly skin
- Weakened tooth enamel (in children)
- Muscle spasms called tetany (can lead to spasms of the larynx, causing breathing difficulties)
- Convulsions (seizures)
Additional symptoms that may be associated with this disease include:
In contrast to hyperparathyroidism (hyperfunction of the parathyroids), hypoparathyroidism does not have consequences for bone.
Diagnosis is by measurement of calcium
, serum albumin
(for correction) and PTH in blood
. PTH degrades rapidly at ambient temperatures and the blood sample therefore has to be transported to the laboratory on ice.
If necessary, measuring cAMP (cyclic AMP) in the urine after an intravenous dose of PTH can help in the distinction between hypoparathyroidism and other causes.
Differential diagnoses are:
Other tests include ECG for abnormal heart rhythms, and measurement of blood magnesium levels.
Hypoparathyroidism can have a number of divergent causes:
- Removal of the parathyroid glands in thyroid surgery (thyroidectomy) is a recognised cause. It is now uncommon, as surgeons generally spare them during the procedure after identifying them.
- Autoimmune invasion and destruction is the most common non-surgical cause. It can occur as part of autoimmune polyendocrine syndromes.
- Hemochromatosis 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
- DiGeorge syndrome, a childhood disease in which hypoparathyroidism occurs due to a total absence of the parathyroid glands at birth. Familial hypoparathyroidism occurs with other endocrine diseases, such as adrenal insufficiency, in a syndrome called type I polyglandular autoimmune syndrome (PGA I).
- Some very rare diseases
- Idiopathic (of unknown cause), occasionally familial
Severe hypocalcemia, a potentially life-threatening condition, is treated as soon as possible with intravenous calcium
(e.g. as calcium gluconate
). Generally, a central venous catheter is recommended, as the calcium can irritate peripheral veins
and cause phlebitis
Long-term treatment of hypoparathyroidism is with calcium and Vitamin D3 supplementation (D1 is ineffective in the absence of renal conversion). Teriparatide, a synthetic form of PTH (presently registered for osteoporosis) might become the treatment of choice for PTH supplementation, although further studies are awaited.
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.