Preoperative Considerations for Patients with Thyroid Disease: 

 

    • Thyroid disease is common, especially in women and older individuals.

    • Patients undergoing surgery may have concomitant thyroid disease.

    • Most well-compensated thyroid disease patients don’t need special preoperative considerations.

    • Patients with newly diagnosed thyroid disorders around the time of surgery should discuss risks and benefits.

    • Preoperative measurement of TSH (thyroid-stimulating hormone) is generally unnecessary in routine preoperative medical consultations.

    • If a patient’s history and physical examination suggest thyroid disease, diagnosis may be pursued for perioperative management.

    • For patients with known thyroid disease taking medication, routine monitoring of thyroid function is recommended at least annually.

    • Additional testing before surgery is usually unnecessary if the patient is on a stable dose of medication and euthyroidism was documented within the past three to six months.

HYPOTHYROIDISM:

Clinical Manifestations of Hypothyroidism Impacting Perioperative Outcome:

 

    • Hypothyroidism affects multiple bodily systems, influencing perioperative outcomes.

    • It leads to decreased cardiac output due to reduced heart rate and contractility.

    • Respiratory muscle weakness and decreased pulmonary responses result in hypoventilation.

    • Hypothyroidism causes decreased gut motility, leading to constipation and ileus.

    • Various metabolic abnormalities can occur, including hyponatremia, increased serum creatinine, and reduced drug clearance.

    • Patients with hypothyroidism often experience normochromic, normocytic anemia.

Severity of Hypothyroidism Definitions:

 

    • Severe Hypothyroidism: Includes patients with myxedema coma, severe clinical symptoms, or very low levels of total thyroxine (T4) or free T4.

    • Moderate Hypothyroidism: Encompasses patients with elevated thyroid-stimulating hormone (TSH) and low free T4, without severe symptoms.

    • Mild Hypothyroidism: Includes patients with subclinical hypothyroidism, characterized by elevated TSH and normal free T4.

Surgical Outcomes Based on Hypothyroidism Severity:

 

    • Mild (subclinical) hypothyroidism generally shows few adverse surgical outcomes.

    • Moderate hypothyroidism may lead to perioperative complications like ileus, hypotension, hyponatremia, and impaired wound healing.

    • Severe hypothyroidism is associated with intraoperative hypotension, cardiovascular collapse, and heightened sensitivity to anesthesia.

Management of Hypothyroidism in Surgery:

 

    • Subclinical hypothyroidism typically doesn’t require surgery postponement.

    • For moderate hypothyroidism, elective surgery may be postponed until euthyroid state restoration, but urgent surgery can proceed with caution.

    • Severe hypothyroidism necessitates treatment and may require postponement of elective surgery.

    • In hospitalized or critically ill patients, assessing thyroid function can be challenging.

    • Nonurgent surgeries should be postponed in critically ill patients with nonthyroidal illness.

    • In urgent surgery cases with suspected hypothyroidism, thyroid hormone replacement is considered.

    • Repletion of thyroid hormone should be cautious and guided by monitoring thyroid function.

HYPERTHYROIDISM:

Clinical Manifestations:

 

    • Hyperthyroidism affects various bodily systems.

    • Increased cardiac output, heart rate, and widened pulse pressure.

    • Atrial fibrillation is common, especially in older patients.

    • Dyspnea may occur due to increased oxygen consumption.

    • Weight loss results from increased calorigenesis and gut motility.

Management:

 

    • Management decisions depend on the severity of hyperthyroidism.

    • Subclinical hyperthyroidism can proceed with elective surgeries.

    • Overt hyperthyroidism should be controlled before elective surgery.

    • Urgent surgery in hyperthyroid patients requires preoperative treatment.

    • Consider evaluation for cardiopulmonary disease and monitor for complications.

    • Use beta blockers (e.g., atenolol) for rate control in some patients.

    • Thionamides (e.g., methimazole) are used for postoperative control.

    • Iodine (SSKI) may be added in severe hyperthyroidism.

    • Extreme caution with iodine in toxic adenoma/multinodular goiter.

    • Consider using iopanoic acid where available.

    • Some patients intolerant to thionamides can use beta blockers and iodine.

    • Thyroid storm is a risk during surgery and in the first 18 hours post-surgery.

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