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- Deficient secretion of parathyroid hormone (PTH)
- Acute hypoparathyroidism with associated hypocalcemia results in tetany, muscle cramps, carpopedal spasm, irritability, altered mental status, convulsion, stridor, and tingling of the circumoral area, hands, and feet.
- Chronic: Lethargy, personality changes, anxiety, blurry vision, parkinsonism, mental retardation
- Acquired hypoparathyroidism:
- Surgical: Removal or damage to parathyroid glands or their blood supply. Thyroid, parathyroid, or radical neck surgery for head and neck cancers
- Autoimmune: Isolated or combined with other endocrine deficiencies in polyglandular autoimmune (PGA) syndrome
- Deposition of heavy metals in gland: Copper (Wilson's disease) or iron (hemochromatosis, thalassemias), radiation-induced destruction, and metastatic infiltration
- Functional hypoparathyroidism: Associated with hypomagnesemia. Hypermagnesemia
- Calcium-sensing receptor (CaSR) abnormalities. Hypocalcemia with hypercalciuria
- HDR or Barakat syndrome: Deafness, renal dysplasia
- Familial: Mutations of the TBCE gene. Abnormal PTH secretions
- 22q11.2 deletion syndrome
- System(s) affected: Endocrine/Metabolic; Musculoskeletal; Nervous; Bones; Kidneys; Parathyroid
- May occur in premature infants.
- Neonates born to hypercalcemic mothers may experience suppression of developing parathyroid glands.
- Congenital absence of parathyroids
- May appear later in childhood as autoimmune or APS-1.
Hypocalcemia is fairly common in elderly; however, rarely secondary to hypoparathyroidism.
Use of magnesium as a tocolytic may induce functional hypoparathyroidism.
More common in women. Affects all ages.
Most common after surgical procedure of the anterior neck. Transient hypoparathyroidism is seen after 24.1% of thyroidectomies, whereas permanent hypoparathyroidism 1.2–3.8%.
Wide variation. Autosomal-dominant hypocalcemia with hypercalciuria (ADHH): 1/70,000 typically in infancy with hypocalcemic seizures
Neck surgery, especially thyroid, neck trauma, head and neck malignancies, family history of hypocalcemia, PGA syndromeGenetics
- Genetic defects may result in X-linked or in autosomal-recessive hypoparathyroidism due to abnormal parathyroid gland development. Associated with mutations in the transcription factor glial-cell missing B (BCMB)
- Mutations in transcription factors or regulators of parathyroid gland development:
- Hypoparathyroidism may present as a component of a larger genetic syndrome (APS-1 or DiGeorge syndrome) or in isolation (X-linked hypoparathyroidism).
- May be autosomal–dominant (DiGeorge), autosomal recessive (APS-1), or X-linked recessive (X-linked hypoparathyroidism)
- Congenital syndromes:
- PGA syndrome type 1: Mucocutaneous candidiasis, hypoparathyroidism, and Addison disease
Intraoperative identification and preservation of parathyroid tissue
- PTH is involved in the control of serum ionized calcium levels:
- Mobilizes calcium and phosphorus from bone stores
- Stimulates formation of 1,25-dihydroxy-vitamin D
- Stimulates reabsorption of calcium in the distal convoluted tubule and phosphate excretion in proximal tubule
- Loss of PTH action results in hypocalcemia, hyperphosphatemia, and hypercalciuria.
- Magnesium is crucial for PTH secretion and activation of the PTH receptor; hypo- or hypermagnesemia may result in functional hypoparathyroidism.
- Postsurgical: Transient, intermittent or permanent irradiation
- Autoimmune: Genetic gain-of-function mutation in calcium-sensing receptor
- Infiltrative: Metastatic carcinoma, hemochromatosis, Wilson disease, granulomas
- Hypo- (alcoholics) or hypermagnesemia: Chronic iron overloads
Commonly Associated Conditions
- DiGeorge syndrome
- PGA syndrome type 1
- Multiple endocrine deficiency autoimmune candidiasis (MEDAC) syndrome
- Juvenile familial endocrinopathy
- Addison disease
- Moniliasis (HAM) syndrome: A polyglandular deficiency syndrome, possibly genetic, characterized by hypoparathyroidism