is a topic covered in the 5-Minute Clinical Consult
To view the entire topic, please sign in or purchase a subscription.
5-Minute Clinical Consult (5MCC) app and website powered by Unbound Medicine helps you diagnose and manage 900+ medical conditions. Exclusive bonus features include Diagnosaurus DDx, 200 pediatrics topics, and medical news feeds. Explore these free sample topics:
-- The first section of this topic is shown below --
- Deficient or absent secretion of parathyroid hormone (PTH), a major hormone regulator of serum calcium and phosphorus levels in the body (1)
- Acute hypoparathyroidism: tetany that is mild (muscle cramps, perioral numbness, paresthesias of hands and feet) or severe (carpopedal spasm, laryngospasm, heart failure, seizures, stridor)
- Chronic: often asymptomatic; lethargy, anxiety/depression, urolithiasis and renal impairment, dementia, blurry vision from cataracts or keratoconjunctivitis, parkinsonism or other movement disorders, mental retardation, dental abnormalities, and dry, puffy, coarse skin
- System(s) affected: endocrine/metabolic, musculoskeletal, nervous, ophthalmologic, renal
- 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
Hypocalcemia is fairly common in elderly, however, rarely secondary to hypoparathyroidism.
- Use of magnesium as a tocolytic may induce functional hypoparathyroidism.
- For women with hypoparathyroidism, calcitriol requirements decrease during lactation.
More common in women; affects all ages
Most common after surgical procedure of the anterior neck (75% of all cases). Transient hyperparathyroidism is seen after 6.9–46% of thyroidectomies, whereas permanent hypoparathyroidism, 0.9–1.6% at experienced centers.
- Affects 24 to 37/100,000 persons per year (1)
- Autosomal dominant hypocalcemia with hypercalciuria (ADHH): 1/70,000 typically in infancy with hypocalcemic seizures
Etiology and Pathophysiology
- PTH aids in regulating calcium homeostasis:
- Mobilizes calcium and phosphorus from bone stores
- Increases calcium absorption from the intestine by stimulating formation of 1,25-dihydroxy vitamin D
- Stimulates reabsorption of calcium in the distal convoluted tubule and phosphate excretion in proximal tubule
- Reduced or absent PTH action results in hypocalcemia, hyperphosphatemia, and hypercalciuria.
- Acquired hypoparathyroidism
- Surgical: removal or damage to parathyroid glands or their blood supply; thyroid, parathyroid, or neck surgery for head and neck cancers (2)
- Autoimmune: isolated or combined with other endocrine deficiencies in polyglandular autoimmune (PGA) syndrome
- Deposition of heavy metals in gland: copper (Wilson disease) or iron (hemochromatosis, thalassemias), radiation-induced destruction, and metastatic infiltration
- Functional hypoparathyroidism: may result from hypomagnesemia or hypermagnesemia because magnesium is crucial for PTH secretion and activation of the PTH receptor
- 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
- Autoimmune: genetic gain-of-function mutation in CaSR
- Infiltrative: metastatic carcinoma, hemochromatosis, Wilson disease, granulomas
- Hypo- (alcoholics) or hypermagnesemia: chronic iron overloads
- X-linked or in autosomal recessive mutations in the transcription factor glial cell missing B (GCMB)
- Mutations in transcription factors or regulators of parathyroid gland development
- Component of a larger genetic syndrome (APS-1 or DiGeorge syndrome) or in isolation (X-linked hypoparathyroidism) (3)
- May be autosomal dominant (DiGeorge), autosomal recessive (APS-1), or X-linked recessive (X-linked hypoparathyroidism) (3)
- Congenital syndromes
- 22q11.2 deletion syndrome, familial hypomagnesemia, hypoparathyroidism with lymphedema (3)
- Hypoparathyroidism with sensorineural deafness
- ADHH: mutations gain-of-function of the CaSR gene suppressing the parathyroid gland, without elevation of PTH
- PGA syndrome type I: mucocutaneous candidiasis, hypoparathyroidism, and Addison disease
Neck surgery and neck trauma, neck malignancies, family history of hypocalcemia, PGA syndrome
Intraoperative identification and preservation of parathyroid tissue
Commonly Associated Conditions
- DiGeorge syndrome
- Bartter syndrome
- PGA syndrome type I
- Multiple endocrine deficiency autoimmune candidiasis (MEDAC) syndrome
- Juvenile familial endocrinopathy
- Addison disease
- Moniliasis (HAM) syndrome: a polyglandular deficiency syndrome, possibly genetic, characterized by hypoparathyroidism
-- To view the remaining sections of this topic, please sign in or purchase a subscription --