Hyperparathyroid, Hypoparathyroid
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4 total
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Posterior aspect of thyroid gland
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Produce and release PTH
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iCal determines level of PTH secretion in body indirectly. Decreased Ca+ = increased PTH
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PTH causes bone resorption, kidney absorption and GI absorption of Ca+
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Prinicipal cells secrete PTH
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Half-life of PTH is 4-5 minutes
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Alkalosis = decreased Ca+
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50% bound to albumin
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40-45% free/ionized
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5-10% bound/unionized
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ionized levels are regulated and affected by pH and temperature
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low pH (acidotic) = increased ionized Ca+
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high pH (alkalosis) = decreased ionized Ca+
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Normal iCal = 4.4-5.4mg/dL
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Normal total calcium = 8.9-10.1mg/dL
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Small changes in iCal leads to large changes in PTH secretion
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Normal serum Ca+ levels = 8.9-10.1mg/dL
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Normal iCal = 4.75-5.7mg/dL; 1.19-1.33mmol/L
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Mild = <3mmol/L; 12mg/dL
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hydration
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Moderate to severe = 3.2-3.7 mmol/L; 13-15 mg/dL
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NS and lasix
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Other treatments
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Ethacrynic acid - Na+/Ca+ diuresis
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Biphosphonates - inhibit bone resorption
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Calcitonin - hormone to oppose PTH (decrease Ca+)
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Airway
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Neuromuscular & CNS
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ECG
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Recurrent laryngeal nerve damage. Unilateral (hoarseness) Bilateral (stridor, obstruction)
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Muscle cramps
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negative inotropy
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Bleeding - tracheal compression and edema
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Chovstek's sign and Trousseau's Sign
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prolonged QT
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Hypocalcemic tetany - laryngospasm
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Parasthesias
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Psychosis
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Seizures
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HYPERCALCEMIA
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Hypercalemia = >10.4 mg/dL
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Primary - most common - due to malignancy or parathyroid malfunction. 30-40 year olds. Single gland is usually benign - 80% prevalence. Secondary - 15% - Hereditary and associated with MEN1 and MEN2A.
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Signs and Symptoms: Renal - Ca+ deposits with recurrent stones. Skeletal - pathologic fractures, skeletal demineralization. CNS - confusion, depression. Neuromuscular - weakness, fatigue. GI - nausea, vomiting, constipation, PUD, anorexia. Cardiac - prolonged PR, short QT, HTN and Osborne J waves.
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Diagnosis: PTH assay with Ca+ level. Will show increased levels of PTH and hypercalcemia.
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Treatment: Mithramycin - inhibits osteoclasts, respiratory alkalosis, Calcitonin (stimulates osteoblasts; inhibits osteoclasts. i.e. Ca + is removed from the blood and used to build bone)
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Most common cause of hypercalcemia is cancer. 25-50% of the time it is breast cancer
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Anesthetic Considerations: Pts will be sensitive to succinylcholine and antagonize non-depolarizing NMBs
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Arms will be tucked - IV access
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NIM endotracheal tube to access nerve integrity
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Consider a deep extubation
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Intraop serum PTH. PTH levels should drop 20 minutes after removal
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Post-op hypocalcemia
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HYPOCALCEMIA, HYPOMAGNESEMIA and HYPERPHOSPHATEMIA
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Absence of deficiency of PTH secretion or resistance of peripheral tissues to PTH
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Cause: Iatrogencic (i.e. inadvertent removal during thyroid surgery)
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Signs and Symptoms: neuronal irritability, muscle spasms, tetany, seizures, fatigue, stridor, apnea, CHF, hypotension, prolonged QT, decreased response to beta agonists, fatigue, Chvostek's sign, Trousseau's sign and mental status changes
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Treatment: electrolyte replacement, avoid respiratory alkalosis (decreases Ca+ further), phosphate binders (Sevalamir). Severe hypocalcemia: 10-20 mL (90mg; 0.46mEq/L) of 10% Calcium Gluconate or 3-5 mL (270mg; 1.36 mEq) of Calcium Chloride followed by 1-2mg/kg/hr or Calcium infusion. Calcium is incompatible with sodium bicarbonate
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Anesthetic Management: be mindful that laryngospasm can occur, seizures, prolonged QT (zofran)
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