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BASICS

  • Deficient or absent secretion of parathyroid hormone (PTH)
  • Acute hypoparathyroidism: mild (cramps, numbness) to severe tetany, laryngospasm, seizures
  • Chronic: often asymptomatic or neuropsychiatric, cataracts, movement disorders, renal impairment
  • Affects endocrine, musculoskeletal, nervous, ophthalmologic, and renal systems

EPIDEMIOLOGY

  • More common in women; affects all ages
  • Most common cause: neck surgery (thyroidectomy, parathyroidectomy)
  • Transient hypoparathyroidism common post-thyroidectomy (6.9-46%)
  • Permanent hypoparathyroidism varies with surgeon experience
  • Prevalence: 24-37 per 100,000 in the US
  • Genetic disorders <10% of cases, but more frequent in children

ETIOLOGY AND PATHOPHYSIOLOGY

  • PTH regulates calcium/phosphorus homeostasis via:
  • Mobilizing calcium/phosphorus from bone
  • Increasing intestinal calcium absorption via 1,25(OH)₂ vitamin D

  • Promoting renal calcium reabsorption and phosphate excretion

  • Reduced PTH → hypocalcemia, hyperphosphatemia, hypercalciuria

  • Acquired causes:

  • Surgical injury or removal during neck surgery
  • Autoimmune polyglandular syndromes
  • Heavy metal deposition (copper, iron), radiation, metastases

  • Functional hypoparathyroidism due to magnesium abnormalities

  • Congenital causes:

  • Calcium-sensing receptor (CaSR) abnormalities
  • Genetic syndromes: HDR/Barakat, 22q11.2 deletion (DiGeorge), familial hypomagnesemia
  • Mutations in transcription factors regulating parathyroid development
  • Autosomal dominant, recessive, or X-linked inheritance patterns

RISK FACTORS

  • Neck surgery or trauma
  • Neck malignancies
  • Family history of hypocalcemia
  • Polyglandular autoimmune syndrome

COMMONLY ASSOCIATED CONDITIONS

  • DiGeorge syndrome
  • Bartter syndrome
  • Polyglandular autoimmune syndrome type I (PGA)
  • Addison disease
  • Multiple endocrine deficiency autoimmune candidiasis (MEDAC) syndrome

DIAGNOSIS

  • History: Often asymptomatic; neuromuscular hyperexcitability symptoms (fatigue, paresthesias, spasms, seizures)
  • Physical exam:
  • Surgical neck scars
  • Chvostek sign (facial nerve twitch)
  • Trousseau sign (carpal spasm on BP cuff inflation)
  • Tetany, laryngospasm, cardiac arrhythmias
  • Dry, coarse hair, brittle nails

  • Cataracts, ectopic calcifications, dental abnormalities

  • Differential: Vitamin D deficiency, pseudohypoparathyroidism (elevated PTH), hypomagnesemia

DIAGNOSTIC TESTS & INTERPRETATION

  • Serum calcium: low total and ionized (correct for albumin)
  • Serum phosphorus: elevated
  • Intact PTH: low (distinguishes from pseudohypoparathyroidism)
  • Magnesium: low or normal
  • 25-OH vitamin D: check for deficiency
  • Renal function tests (BUN, creatinine)
  • Urinary calcium: normal or high
  • Imaging: may show absent tooth roots, basal ganglia or cerebellar calcifications
  • ECG: prolonged ST and QTc, arrhythmias

TREATMENT

General Measures

  • Monitor ECG during calcium replacement
  • Lifelong calcium and calcitriol supplementation usually required
  • Maintain serum calcium in low normal range (8.0–8.5 mg/dL)
  • Treat magnesium deficiency
  • Use phosphate binders if calcium-phosphate product elevated
  • Thiazide diuretics with low-salt diet may reduce hypercalciuria

Medications

  • Acute severe hypocalcemia:
  • IV calcium gluconate 1–2 g over 10 minutes (central line preferred)

  • Follow with continuous infusion in D5W at 1–3 mg/kg/hr

  • Chronic therapy:

  • Oral calcium carbonate (preferred; better absorption with meals)
  • Calcium citrate (if on PPI or constipation with carbonate)
  • Calcitriol (0.25–2.0 µg/day)
  • Thiazide diuretics for hypercalciuria

  • Low phosphate diet or binders if phosphate >6.5 mg/dL

  • Pediatric dosing: calcium 25–50 mg/kg daily, calcitriol 0.25 µg daily (>1 year)

Additional Therapies

  • Recombinant PTH peptides (1-34 or 1-84) for refractory cases
  • FDA approved rhPTH 1-84, 50 µg SC daily
  • Benefits include reduced calcium/vitamin D requirements and improved bone density

SURGERY/OTHER PROCEDURES

  • Autotransplantation of cryopreserved parathyroid tissue: restores normocalcemia in ~23%

ADMISSION, INPATIENT, AND NURSING CONSIDERATIONS

  • Admit if laryngospasm, seizures, tetany, or prolonged QT
  • Discharge once symptoms resolve and patient educated

ONGOING CARE

  • Maintain serum calcium 8.0–8.5 mg/dL, 24-hour urine calcium <300 mg
  • Monitor serum calcium, phosphate, magnesium, creatinine weekly to monthly initially, then every 6 months when stable
  • Yearly 24-hour urine calcium and creatinine
  • Renal imaging every 5 years if stones or rising creatinine
  • Annual ophthalmologic exam (slit lamp)
  • Routine DEXA scans

DIET

  • Low phosphate diet if hyperphosphatemia present

PATIENT EDUCATION

  • Refer to hypoparathyroidism support resources: https://www.hypopara.org/

PROGNOSIS

  • Often transient post-surgery; duration varies by cause
  • Lifelong treatment usually necessary in permanent cases

COMPLICATIONS

  • Reversible: neuromuscular symptoms, tetany, seizures
  • Renal: hypercalciuria, nephrocalcinosis, nephrolithiasis
  • Cardiovascular: arrhythmias, heart failure
  • Irreversible in early childhood cases: growth retardation, dental defects, cataracts, nail abnormalities, basal ganglia calcifications

REFERENCES

  1. Abate E, Clarke B. Review of hypoparathyroidism. Front Endocrinol (Lausanne). 2017;7:172.
  2. Al-Azem H, Khan A. Hypoparathyroidism. Best Pract Res Clin Endocrinol Metab. 2012;26(4):517-522.
  3. Bilezikian JP, Khan A, Potts JT Jr, et al. Hypoparathyroidism in the adult: epidemiology, diagnosis, pathophysiology, target-organ involvement, treatment, and challenges for future research. J Bone Miner Res. 2011;26(10):2317-2337.
  4. Brandi M, Bilezikian D, Shoback D, et al. Management of hypoparathyroidism: summary statement and guidelines. J Clin Endocrinol Metab. 2016;101(6):2273-2283.

Clinical Pearls

  • Consider hypoparathyroidism in patients with hypocalcemia and fatigue, paresthesias
  • Correct serum calcium for albumin
  • Monitor calcium closely after neck surgery
  • Differentiate from pseudohypoparathyroidism by PTH levels
  • Measure magnesium and 25-OH vitamin D to exclude contributing deficiencies