Hypoparathyroidism
Hypoparathyroidism is PTH deficiency causing hypocalcemia and hyperphosphatemia, most often from inadvertent parathyroid injury during anterior neck surgery. First-line treatment is oral calcium plus calcitriol titrated to a low-normal serum calcium, with recombinant PTH reserved for inadequate control.
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What this article covers
- Overview
Definition: Hypoparathyroidism is deficient parathyroid hormone (PTH) secretion, producing hypocalcemia and hyperphosphatemia because too little PTH reaches bone and kidney to mobilize calcium and excrete phosphorus.
- Epidemiology
Leading setting: anterior neck surgery is the dominant setting for acquired hypoparathyroidism, given the volume of thyroidectomy and parathyroidectomy performed.
- Risk factors
Extensive or repeat neck surgery: total thyroidectomy, completion thyroidectomy, central neck dissection, or parathyroidectomy for multigland disease raises the risk of injuring or devascularizing the parathyroid glands.
- Pathophysiology
PTH's normal role: PTH raises serum calcium by mobilizing calcium from bone, increasing kidney calcium reabsorption, increasing kidney phosphorus excretion, and stimulating renal conversion of…
- Clinical features
Diagnostic core feature: hypocalcemia with a low or inappropriately normal PTH is the defining biochemical feature that establishes hypoparathyroidism once hypomagnesemia has been excluded.
- Differential diagnosis
Pseudohypoparathyroidism: end-organ PTH resistance produces hypocalcemia and hyperphosphatemia, but unlike hypoparathyroidism the PTH level is elevated, not low.
- Diagnosis
Diagnostic basis: the diagnosis is confirmed by a repeat measurement showing hypocalcemia (corrected for albumin, or measured as ionized calcium if acute alkalosis is present) together with a PTH…
- Management
First, treat severe or symptomatic hypocalcemia urgently for critical calcium values or overt tetany, laryngospasm, or seizure: 10% calcium gluconate 1-2 g IV over 10-20 minutes then a continuous…
- Complications
Nephrocalcinosis and nephrolithiasis: long-term hypercalciuria, especially from overtreatment toward a fully normal serum calcium, deposits calcium in the kidney and can impair function.
- Prognosis
Surgical hypoparathyroidism: most postsurgical cases are transient, resolving over days to weeks as residual parathyroid tissue recovers function; a minority progress to permanent disease requiring lifelong therapy.
- Prevention
Preoperative vitamin D correction: correcting vitamin D deficiency before neck surgery minimizes postoperative hypocalcemia related to relative hypoparathyroidism and hungry bone syndrome.
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Related articles
- Hypocalcemia
Hypocalcemia is a low serum calcium concentration, most often from insufficient parathyroid hormone action (postsurgical or autoimmune hypoparathyroidism, hypomagnesemia, or PTH resistance) or from vitamin D deficiency and chronic kidney disease. Severe or symptomatic disease requires urgent intravenous calcium, while chronic disease is managed with oral calcium, vitamin D repletion, and calcitriol when PTH is absent or the kidney cannot activate vitamin D.
- Pseudohypoparathyroidism
Pseudohypoparathyroidism is a rare genetic cause of hypocalcemia from end-organ (kidney and bone) resistance to parathyroid hormone, most often from a maternally inherited inactivating GNAS mutation that produces the Albright hereditary osteodystrophy phenotype alongside hypocalcemia, hyperphosphatemia, and an elevated, not low, PTH level. Acute symptomatic hypocalcemia is treated with intravenous calcium, and chronic disease is managed with oral calcium and calcitriol.
- Vitamin D deficiency rickets
Vitamin D deficiency rickets is defective mineralization of the growing cartilaginous growth plate from inadequate vitamin D, most often in a breastfed infant without supplementation, presenting with bowing of the legs, a rachitic rosary, and delayed motor development around 15 months of age. Diagnosis rests on a low 25-hydroxyvitamin D with elevated parathyroid hormone and characteristic metaphyseal cupping and fraying on long-bone radiographs, and first-line treatment is ergocalciferol 2,000 IU PO once daily for 6 weeks with calcium supplementation.