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| ==Signs and symptoms==
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| [[Hypocalcemia]] is the only real result of parathyroid dysfunction and low PTH levels. This presents with [[tremor]], [[tetany]] and, eventually, [[convulsion]]s.
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| In contrast to [[hyperparathyroidism]] (hyperfunction of the parathyroids), hypoparathyroidism does not have consequences for [[bone]].
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| ==Diagnosis==
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| Diagnosis is by measurement of [[calcium]], [[serum albumin]] (for correction) and [[PTH]] in [[blood test|blood]]. [[PTH]] degrades rapidly at ambient temperatures and the blood sample therefore has to be transported to the laboratory on ice.
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| If necessary, measuring [[Cyclic adenosine monophosphate|cAMP]] ([[cyclic AMP]]) in the urine after an intravenous dose of [[PTH]] can help in the distinction between [[hypoparathyroidism]] and other causes.
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| Differential diagnoses are:
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| * [[Pseudohypoparathyroidism]] (normal [[PTH]] levels but tissue insensitivity to the hormone, associated with [[mental retardation]] and [[skeleton|skeletal deformities]]) and [[pseudopseudohypoparathyroidism]] (''sic'').
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| * Deficiency of [[Vitamin D]] or hereditary insensitivity to this vitamin (X-linked dominant).
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| * [[Malabsorption]]
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| * [[Kidney disease]]
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| * Medication: [[steroid]]s, [[diuretic]]s, some [[antiepileptic]]s.
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| ==Causes==
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| Hypoparathyroidism can have a number of divergent causes:
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| * Removal of the parathyroid glands in [[thyroid]] surgery ([[thyroidectomy]]) is a recognised cause. It is now uncommon, as [[surgery|surgeon]]s generally spare them during the procedure after identifying them.
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| * [[Autoimmune disorder|Autoimmune]] invasion and destruction is the most common non-surgical cause. It can occur as part of [[autoimmune polyendocrine syndrome]]s.
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| * [[Hemochromatosis]] can lead to iron accumulation and consequent dysfunction of a number of endocrine organs, including the parathyroids.
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| * Absence or dysfunction of the parathyroid glands is one of the components of [[Chromosome 22, microdeletion 22 q11|chromosome 22q11 microdeletion syndrome]] (other names: DiGeorge syndrome, Schprintzen syndrome, velocardiofacial syndrome).
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| * [[Magnesium]] deficiency
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| * Some very [[rare disease]]s
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| * Idiopathic (of unknown cause), occasionally familial
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| ==Treatment==
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| 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 vein]]s and cause [[phlebitis]].
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| 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.
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| ==Related Chapters== | | ==Related Chapters== |