Hypoparathyroidism

Hypoparathyroidism is decreased function of the

Hypoparathyroidism can have the following causes:[1]

• Removal of, or trauma to, the parathyroid glands due to anterior neck surgery (including thyroid surgery) (thyroidectomy), parathyroid surgery (parathyroidectomy). This is the most common cause of hypoparathyroidism, with 78% of cases of hypoparathyroidism arising due to a complication of anterior neck surgery.^[5] Although surgeons 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). Hypoparathyroidism may occur as a complication in up to 8% of anterior neck surgeries with 75% of those resolving by 6 months, and 25% of those having permanent hypoparathyroidism.^[5]
• Kenny-Caffey Syndrome
• 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
• 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

PTH acts on several organs to regulate calcium levels and phosphorus levels. PTH acts on the kidneys to increase calcium reabsorption into the blood, and to inhibit phosphorus reabsorption (which causes phosphorus to be lost in the urine).[5] It increases calcium and phosphorus absorption in the bowel indirectly by stimulating the kidneys to produce vitamin D which then acts on the gut.^[5] PTH also causes increase bone resorption which leads to the releases calcium and phosphorus into the blood.^[5]

Diagnosis

Diagnosis is by measurement of calcium, serum albumin (for correction) and PTH in blood. 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.^{[citation needed]}

Differential diagnoses are:

• Pseudohypoparathyroidism (normal PTH levels but tissue insensitivity to the hormone, associated with intellectual disability and skeletal deformities) and pseudopseudohypoparathyroidism.^[7]
• Vitamin D deficiency or hereditary insensitivity to this vitamin (X-linked dominant).
• Malabsorption
• Kidney disease
• Medication:
  antiepileptics
  .

Other tests include

A 2019 systematic review has highlighted that there is a lack of high-quality evidence for the use of vitamin D, calcium, or recombinant parathyroid hormone in the management of both temporary and long-term hypoparathyroidism following thyroidectomy.^[10]

• Hyperparathyroidism

References