CHAPTER 34. Endocrine Care
Laura Currie
OBJECTIVES
At the conclusion of this chapter, the reader will be able to:
1. Describe the basic function of the endocrine system including the hormones produced by the thyroid, parathyroid, pituitary, and adrenal glands.
2. Identify the signs, symptoms, and diagnostic testing used to assess endocrine gland function.
3. Identify the surgical procedure and perioperative considerations for the patient with hyperthyroidism, hypothyroidism, pheochromocytoma, hypersecretion and hyposecretion of the pituitary and adrenal glands.
4. Identify the postanesthesia plan of care for the patient having subtotal thyroidectomy, bilateral adrenalectomy, hypophysectomy, and parathyroidectomy.
5. Discuss the postanesthesia considerations of the patient with endocrine dysfunctions: thyrotoxicosis, hypercalcemia, Cushing’s syndrome, Addison’s disease, diabetes insipidus, syndrome of inappropriate antidiuretic hormone.
6. Discuss the postanesthesia care of the diabetic patient and diabetic emergencies: hypoglycemia, diabetic ketoacidosis, and hyperglycemic hyperosmolar syndrome.
I. THYROID GLAND
A. Anatomy and physiology (Figure 34-1)
1. Location
a. Sits in anterior portion of the neck
b. Right lobe below the larynx
c. Left lobe beside the trachea
d. Middle portion called the isthmus lies at the base of the neck between second and fourth tracheal rings.
2. Blood supply from external carotid arteries
3. Nerve supply from cervical sympathetic trunk
4. Functions of thyroid gland
a. Regulates energy, metabolism and growth, and development
(1) Hormone production from the hypothalamic-pituitary-thyroid axis
(a) Hypothalamus secretes thyrotropin-releasing hormone (TRH)→stimulates the anterior pituitary to secrete thyroid-stimulating hormone (TSH)→increases the production of the thyroid hormones (THs) thyroxine (T 4) and triiodothyronine (T 3) and the uptake of iodide
(2) Negative feedback loop (Figure 34-2)
(a) Hypothalamus secretes TRH to regulate the synthesis and release of TSH.
(b) When TH levels decrease, TSH and TRH levels increase.
(c) Conversely, if TH levels increase, TSH and TRH levels decrease.
 |
| FIGURE 34-2 ▪ Hypothalamus-pituitary-thyroid axis. |
b. T 3 has a short half-life, and T 4 has a half-life of 5 to 7 days.
c. Peripheral tissue converts T 4 to T 3.
d. T 3 considered the true tissue TH
e. T 4 considered a plasma prohormone
B. Comparison of hyperthyroid and hypothyroid conditions (Table 34-1)
| T3 , Triiodothyronine; T4, thyroxine; TSH, thyroid-stimulating hormone. | ||
| Hyperthyroid | Hypothyroid | |
|---|---|---|
| Description | Excessive secretion of thyroid hormones | Insufficient secretion of thyroid hormones |
| Causes | Multinodular, toxic, diffuse enlargement (goiter)—Graves’ disease Malignancy Thyroiditis Viral, autoimmune Excessive iodine intake Amiodarone toxicity secondary to high concentrations of iodine; inhibits the conversion of T 4 to T 3 | Chronic thyroiditis—progressively destroys thyroid function (Hashimoto’s thyroiditis) Autoimmune diseases Iodine deficiency Surgical removal of thyroid Secondary dysfunction related to pituitary problems Tertiary dysfunction related to hypothalamus problems |
| Signs and symptoms | Cardiopulmonary Hypertension Tachycardia or new atrial fibrillation Low blood pressure—fluid loss Potential heart failure Tachypnea Eyes/Ears/Nose/Throat Exophthalmos Enlarged thyroid /goiter Hoarseness/difficulty swallowing Gastrointestinal Weight loss Increased peristalsis Diarrhea and abdominal pain Musculoskeletal Body thinness Muscle atrophy and weakness Skin Diaphoresis Fine, silky, thin hair Hyperpigmentation Nervous System Hyperactive emotional state Heat intolerance Insomnia Genitourinary Menstrual cycle changes Infertility | Cardiopulmonary Bradycardia Decreased cardiac output High blood pressure—fluid retention Peripheral vasoconstriction Increased cholesterol levels Eyes/Ears/Nose/Throat Puffy eyes, enlarged tongue Goiter Hoarseness/difficulty swallowing Gastrointestinal Weight gain Constipation Musculoskeletal Muscle weakness Joint pain Skin Dry Alopecia Myxedema (late) Nervous System Fatigue, inability to concentrate Miscellaneous Cold intolerance Genitourinary Heavy menstrual bleeding Infertility |
| Diagnostic tests | TSH decreased T 3 increased Free T 4 increased Thyroid scan: radioactive iodine uptake Ultrasonography: identification of tumor type Fine-needle aspiration | TSH increased T 3 decreased Free T 4 decreased |
| Operative procedures to correct condition | Purpose: remove tracheal/esophageal obstructions or malignancy Subtotal thyroid lobectomy (partial lobe) Thyroid lobectomy (total lobe) Total thyroidectomy (removal of entire gland) | No specific surgery Comorbid condition |
| Preoperative objectives | Promote a euthyroid state by: Regulating antithyroid drugs Controlling hyperdynamic cardiac status Educate patient and family related to type of surgery/procedure, incision site, drains, and pain. Thyroid surgery–specific head and neck support when turning | Promote a euthyroid state by: Regulating thyroid replacement Educate patient and family related to type of surgery/procedure, incision site, drains, and pain. |
| Anesthesia concerns | Corneal drying or abrasions Considerations of agents based on euthyroid state Stability of cardiac status Airway status Oxygen requirements increased with hypermetabolic state and increased temperature Vocal cord visualization for injury to recurrent laryngeal nerves | Predisposition to hypothermia, cardiac failure, and delayed gastric emptying Metabolism of medications may be delayed. Adrenal insufficiency: may consider glucocorticoids to correct insufficiency Neuromuscular weakness may affect weaning. Potential difficult intubation secondary to predisposition for an enlarged tongue |
C. Medical therapy: goal is to promote a euthyroid state.
1. Hyperthyroid conditions
a. Inhibition of TH synthesis
(1) Propylthiouracil: 600- to 1000-mg loading dose followed by 200 to 250 mg every 4 hours
(a) Blocks conversion of T 4 and T 3
(b) Administered at least 6 to 12 weeks preoperatively to achieve euthyroid state
(c) Avoid acetylsalicylic acid because it displaces T 3 from protein binding.
(2) Methimazole: 60 to 120 mg/day in divided doses
(a) Blocks uptake of iodine
(b) Administered 6 to 12 weeks preoperatively to achieve euthyroid state
b. Inhibition of TH release
(1) Saturated solution of potassium iodide
(a) 50 mg iodine per drop: 1 to 2 drops three times per day
(b) Iodide blocks T 4 release from the thyroid gland.
(c) Acute management
(2) Lugol’s solution (5% iodine, 10% potassium solution)
(a) 8 mg iodine per drop
(b) Acute management: 4 to 8 drops Lugol’s solution or saturated solution of sodium iodide every 6 to 8 hours; administer at least 2 to 3 hours after initial dosing of inhibitors of TH synthesis.
(3) Lithium carbonate: 300 mg every 6 hours
c. Inhibition of sympathetic nervous system innervation
(1) Beta-blockers first choice
(a) Propanolol: 0.5 to 1 mg intravenously (IV) every 15 minutes as needed, as loading dose until onset of action of oral propranolol (60-80 mg every 4 hours)
(b) Esmolol: loading dose of 250 to 500 mcg/kg followed by infusion of 50 to 100 mcg/kg per minute
(2) Calcium channel blockers if unable to tolerate beta-blockers
d. Prevent peripheral conversion of T 4 to T 3 during acute thyrotoxic storm.
(1) Hydrocortisone: 300 mg initially, followed by 100 mg every 8 hours IV
(2) Dexamethasone: 2 mg IV every 6 hours
(3) Prednisone: 40 mg/day—amiodarone-induced thyrotoxicosis
2. Hypothyroid conditions
a. Replace hormone
(1) Chronic—levothyroxine: 1 to 1.5 mcg/kg per day orally initially; adjust as needed every 6 weeks until TSH in normal range; average dosage 1.6 to 1.8 mcg/kg per day (1.3 mcg/kg per day in the elderly)
(2) Acute—myxedema coma: initial dosage 200 to 500 mcg IV daily; reduce dosage to 50 to 100 mcg IV daily until patient is able to take medication orally.
D. Postanesthesia nursing plan of care (Boxes 34-1 and 34-2)
BOX 34-1
DIFFERENCES BETWEEN THYROTOXIC CRISIS AND MALIGNANT HYPERTHERMIA
| Thyrotoxic Crisis | Malignant Hyperthermia | |
|---|---|---|
| Trigger | Increase in circulating thyroid hormones due to physiological stress | Exposure to anesthetic agents such as succinylcholine and/or volatile inhalation agents |
| Acute signs and symptoms | Hyperthermia Tachycardia Hypercarbia No muscle rigidity | Hyperthermia Tachycardia Hypercarbia Muscle rigidity |
| Treatment | Beta Blockers Steroids | Dantrolene sodium |
BOX 34-2
POSTANESTHESIA NURSING PLAN OF CARE: THYROID SURGERY/CONDITIONS
Managing Hyperthyroid Conditions After Thyroid Surgery
Nursing Diagnosis
▪ Ineffective airway clearance related to edema of surgical area
▪ Impaired gas exchange related to increased metabolic demands
▪ Alteration in tissue perfusion related to hyperdynamic metabolic state
▪ Ineffective thermoregulation related to hyperdynamic metabolic state
Interventions
Airway Management
▪ Assess for signs of distress resulting from edema of the glottis or hematoma formation: dyspnea, cyanosis, stridor, retraction of neck muscles, tracheal deviation.
▪ Manage secretions to decrease strain on incision line caused by coughing.
▪ Manage oxygenation secondary to increased metabolic demands with supplemental humidified oxygen.
▪ Manage ventilation by monitoring rate, depth, and acid-base balance (arterial blood gases).
Cardiac Status
▪ Assess cardiac status secondary to hypermetabolic state, activation of the sympathetic nervous systems from the stress of surgery.
Wound Management
▪ Assess incision line for wound hemorrhaging (early complication) and report immediately.
▪ Monitor drainage devices if used.
▪ Assess laryngeal nerve damage by quality of vocalization and ability to swallow.
Positioning
▪ Maintain proper positioning after surgery.
30 ° or higher head positioning
Proper neck support by avoiding extreme head flexion or extension
General
▪ Monitor for tetany and hypocalcemia if combined with removal of parathyroid glands.
Laryngeal spasm, tingling in toes, fingers, mouth
Positive Chvostek’s sign: twitching of facial muscles if cheek is tapped over facial nerve
Positive Trousseau’s sign: carpopedal spasm if circulation in arm is impeded with blood pressure cuff
▪ Monitor for thyrotoxic crisis (storm) versus malignant hyperthermia (see Box 34-1).
Managing Hypothyroid Conditions After Surgery
Nursing Diagnosis
▪ Impaired gas exchange related to decreased metabolism of medications
▪ Ineffective airway clearance related to neurological weakness
▪ Ineffective thermoregulation related to decreased metabolic state
▪ Alteration in tissue perfusion related to decreased metabolic state
Interventions
Airway Management
▪ Assess for signs of distress related to neurological weakness, sensitivity to medications, and predisposition for an enlarged tongue.
▪ Manage oxygenation secondary to decreased metabolism of medications.
▪ Manage ventilation by monitoring rate, depth, and acid-base balance (arterial blood gases).
Cardiac Status
▪ Assess for signs and symptoms of low cardiac output/heart failure.
▪ Assess for bradycardia.
Thermoregulation
▪ Monitor temperature secondary to predisposition to hypothermia.
II. PARATHYROID GLANDS (see Figure 34-1)
A. Anatomy and physiology
1. Consists of four small ovoid masses of tissue lying behind the thyroid gland
2. Parathyroid hormone (PTH) secreted from parathyroid glands
a. PTH and vitamin D responsible for the regulation of calcium and phosphorous
b. Serum calcium maintained by:
(1) Regulating bone turnover
(2) Absorption of calcium from the gut (with vitamin D)
(3) Release of calcium in the urine
c. PTH release inhibited by rising serum calcium level
d. PTH release dependent on normal serum magnesium levels
B. Hyperparathyroid disease (Table 34-2)
 |
 |
| FIGURE 34-1 ▪ Anatomy of thyroid and parathyroid gland. (From Thibodeau GA, Patton KT: Anatomy & physiology, ed 6, St Louis, 2007, Mosby.) |
| H2, Histamine type 2; PTH, parathyroid hormone. | ||
| *Normal values vary with laboratories. | ||
| Primary Hyperparathyroidism | Secondary Hyperparathyroidism | |
|---|---|---|
| Description | Excessive secretion of PTH, resulting in hypercalcemia | Hyperplasia of the parathyroid secondary to the dysfunction of another organ or secondary to another condition |
| Causes | Adenomas (single or multiple gland) most common Hyperplasia of one or more glands Malignancies (rare) Previous head or neck radiation | Vitamin D conditions (deficiency, malabsorption, metabolism, osteomalacia [i.e., rickets]) Calcium disorders Phosphate disorders Chronic renal failure |
| Signs and symptoms | Result from hypercalcemia: Cardiopulmonary Hypertension Dysrhythmias Nervous System Irritability Somnolence Lethargy Genitourinary Renal calculi Polyuria Musculoskeletal Osteopenia and osteoporosis Muscle weakness Joint or back pain Gastrointestinal Abdominal pain Constipation Nausea Risk for gastric ulcers and pancreatitis | |
| LABORATORY TESTS* | ||
| PTH | Normal: 10–65 mg/mL Hyperparathyroid conditions: Elevated | |
| Ionized calcium | Normal: 4.5–5.6 mg/dL Hyperparathyroid conditions: Elevated | |
| Calcium | Normal: 9.0–10.5 mg/dL Hyperparathyroid conditions: Elevated | |
| Phosphorus | Normal: 2.5–4.5 mg/dL Hyperparathyroid conditions: Decreased | |
| Operative procedures to correct condition | Surgical removal of parathyroid Total parathyroidectomy: removal of all glands Partial parathyroidectomy: removal of up to 3.5 of 4 glands Minimally invasive parathyroidectomy | |
| Preoperative objectives | Treat hypercalcemia and correct associated conditions. Saline hydration and furosemide administration for rapid correction Calcitonin Mithramycin for thrombocytopenia and renal problems Prednisone Dysrhythmia management Educate patient and family related to type of surgery/procedure, incision site, drains, and pain. Parathyroid surgery–specific head and neck support when turning | |
| Anesthesia concerns | Intravascular volume changes Postoperative airway obstruction related to recurrent laryngeal nerve injury or bleeding Renal, cardiac, and nervous system abnormalities Consider prophylaxis with H 2 receptor blockers. | |
C. Postanesthesia nursing plan of care (Box 34-3)
BOX 34-3
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POSTANESTHESIA NURSING PLAN OF CARE: PARATHYROID SURGERY
Nursing Diagnosis
▪ Ineffective airway clearance related to edema of surgical area
▪ Impaired gas exchange related to postoperative bleeding or swelling or inability to move secretions
▪ Alteration in fluid and electrolyte balance secondary to total or partial removal of parathyroid gland(s)
▪ Alteration in tissue perfusion related to cardiac dysrhythmias
▪ Altered sensory perception related to postoperative hypocalcemia
Interventions
Airway Management
▪ Assess for signs of distress resulting from edema of the glottis or hematoma formation: dyspnea, cyanosis, stridor, retraction of neck muscles, tracheal deviation.
▪ Manage secretions to decrease strain on incision line caused by coughing.
▪ Manage oxygenation secondary to increased metabolic demands with supplemental humidified oxygen.
▪ Manage ventilation by monitoring rate, depth, and acid-base balance (arterial blood gases).
Cardiac Status
▪ Assess cardiac status secondary to hypocalcemia.
Wound Management
▪ Assess incision line for wound hemorrhaging or hematoma and report immediately.
▪ Assess laryngeal nerve damage by quality of vocalization and ability to swallow.
▪ Maintain proper positioning after surgery.
30 ° or higher head positioning
Proper neck support by avoiding extreme head flexion or extension
General
▪ Monitor for tetany and hypocalcemia with removal of parathyroid glands (immediate to 72 hours postoperatively).
Laryngeal spasm, tingling in toes, fingers, mouth
Positive Chvostek’s sign: twitching of facial muscles if cheek is tapped over facial nerve
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