Hypoparathyroidism

Background

  • Parathyroid hormone (PTH) increases osteolysis, renal tubular resorption of calcium, and renal synthesis of 1,25-dihydroxycholecalciferol AND inhibits renal tubular reabsorption of phosphate and bicarbonate, leading to net INCREASE in serum calcium
  • Hypoparathyroid thus results in hypocalcemia with hyperphosphatemia

Causes

  • Iatrogenic:
    • Anterior neck surgery or radiation (e.g. resection of multiple parathyroid adenomas, thyroidectomy); may be transient
    • steroids, diuretics, antiepilptics
  • Congenital (e.g. DiGeorge syndrome)
  • Malignancy
  • Autoimmune
  • Damage from Heavy metals (e.g. copper in Wilson's disease)
  • Functional hypoPTH from hypomagnesemia

Clinical Features

Differential Diagnosis

  • Vitamin D deficiency
  • Pseudohypoparathyroidism (renal resistance to PTH)
  • Kidney disease
  • Malabsorption
  • Iatrogenic:
    • Anterior neck surgery or radiation (e.g. resection of multiple parathyroid adenomas, thyroidectomy); may be transient
    • steroids, diuretics, antiepilptics
  • Congenital (e.g. DiGeorge syndrome)
  • Malignancy
  • Autoimmune
  • Damage from Heavy metals (e.g. copper in Wilson's disease)
  • Functional hypoPTH from hypomagnesemia

Evaluation

  • CPM
    • Low serum calcium
    • Normal alk phos
  • PTH (low or inappropriately normal in setting of hypocalcemia)
  • EKG
  • Magnesium levels
  • Phosphate levels (high)

Management

  • Treat underlying condition

Hypocalcemia

Avoid empiric treatment in patients taking digoxin due to risk for Stone Heart

  • Asymptomatic
    • Calcium gluconate 1 gm PO Q6hrs
    • Vitamin D (calcitriol) 0.2 mcg BID
  • Symptomatic
    • Calcium gluconate/chloride 10mL of 10% soln IV over 10min
  • Correct hypomag at same time (otherwise PTH is inhibited)
  • Avoid phenothiazine antipsychotics (may precipitate extrapyramidal symptoms)
  • Avoid furosemide (may worsen hypocalcemia)

Disposition

See Also

External Links

References