Parathyroid Gland Dysfunction

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Parathyroid Gland Dysfunction

• Excela Health School of Anesthesia

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Parathyroids
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Parathyroid Hormone

• Released into circulation by negative feedback
• PTH release stimulated by hypocalcemia
• PTH maintains normal serum calcium levels

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Hyperparathyroidism

• PTH level elevated
• Serum calcium levels may be increased, decreased,
  or unchanged
• Classified as primary, secondary, or ectopic

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Primary Hyperparathyroidism

• Excessive secretion PTH from benign parathyroid
  adenoma, carcinoma of parathyroid, or hyperplasia
  of parathyroid glands
• Benign adenoma responsible for 90 primary
  carcinoma for 5
• Hyperplasia usually involves all 4 parathyroids

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Primary Hyperparathyroidism

• Diagnosis
• serum calcium gt5.5 mEq/L ionized calcium
• concentration gt2.5 mEq/L
• Measurement of serum parathyroid hormone
  concentration is not always sufficiently reliable
  to confirm the diagnosis of primary
  hyperparathyroidism

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Primary Hyperparathyroidism

• Signs Symptoms
• early sedation, vomiting
• others skeletal muscle weakness, hypotonia
  that may mimic myasthenia gravis
• persistent increases in plasma calcium
  concentration can interfere with urine
  concentrating ability with resulting polyuria
• Oliguric renal failure in advanced cases of
  hypercalcemia (see handout)

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Primary Hyperparathyroidism

• Treatment Initially by medical means followed by
  surgical removal of diseased area(s)
• Medical Saline infusion (150ml/hour) for pts.
  with symptomatic hypercalcemia
• Loop diuretics (furosemide 40-80mg IV q 2-4
  hours
• Do not administer thiazide diuretics for
  hypercalcemia

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Primary Hyperparathyroidism

• Medical Treatment for Life Threatening
  Hypercalcemia Use of Bisphosphonates such as
  disodium etidronate
• binds to hydroxyapetite and acts as potent
  inhibitor of osteoclastic bone reabsorption
• Hemodialysis can also be considered

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Primary Hyperparathyroidism

• Surgical Management Normalization of serum
  calcium levels within 3-4 days
• postoperative potential complication is
  hypocalcemic tetany
• a hypomagnesemia may occur postop that will
  aggravate the hypocalcemia and may render it
  refractory to treatment

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Primary Hyperparathyroidism

• Anesthetic Management No specific drugs or
  techniques
• Maintain hydration and urinary output
• If somnolent preop anesthestic requirements
  decreased
• If coexisting renal dysfunction use of
  sevoflurane is questionable
• Careful use of muscle relaxants and
  monitoring
• Careful positioning

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Secondary Hyperparathyroidism

• A disease process produces hypocalcemia and
  parathyroids compensate by secreting more
  parathyroid hormone (ex. Chronic renal disease)
• Since secondary hyperparathyroidism is adaptive,
  rather than autonomous, it seldom produces
  hypercalcemia
• Treatment Treat underlying disease

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Ectopic Hyperparathyroidism

• Due to secretion of parathyroid hormone by
  tissues other than the parathyroid glands
• (ex. Humoral hpercalcemia of malignancy,
  cancer of lung, breast, pancreas, kidney)
• Likely to be associated with anemia

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Hypoparathyroidism

• PTH absent or deficient, or peripheral tissues
  are resistant to the effects of PTH
• Absence or deficiency of PTH almost always
  iatrogenic (inadvertent removal)
• Diagnosis Measurement of serum calcium
  concentrations and the ionized fractions of
  calcium is best indicator
• Signs Symptoms Depend of the rapidity of the
  onset of hypocalcemia

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Acute Hypocalcemia

• Can occur after accidental removal
• Likely to manifest as perioral paresthesias,
  restlessness, neuromuscular irritability, as
  evidenced by a positive Chvosteks sign or
  Trousseaus sign
• Treatment Infusion of calcium (10 ml of 10
  calcium gluconate IV) until signs of
  neuromuscular irritability disapper

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Chronic Hypocalcemia

• Associated with complaints of fatigue and
  skeletal muscle cramps
• Prolonged QT
• Neurological lethargy, cerebration deficits,
  personality changes
• CRF is most common cause of chronic hypocalcemia

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Anesthesia Management

• Management of anesthesia in presence of
  hypocalcemia is designed to treat any further
  decreases in serum calcium and to treat adverse
  effects of hypocalcemia on the heart so avoid
  iatrogenic hyperventilation
• rapid infusions of blood (500 ml q 5-10 min) as
  during CPB or liver transplantation can decrease
  ionized calcium concentration
• when metabolism or elimination of citrate is
  impaired as with hypothermia, cirrhosis, renal
  dysfunction