Introduction
Endocrine disorders are not uncommon in clinical practice. The abnormalities can range from subclinical hypothyroidism to overt pheochromocytoma. An uncontrolled and poorly optimized state can lead to intraoperative as well as postoperative complications. Therefore, it is mandatory to do a proper clinical evaluation in order to identify and diagnose the abnormal functioning of the pancreas, thyroid, and adrenal glands. This chapter highlights the important perioperative considerations of common endocrine disorders.
Diabetes Mellitus
It is one of the most common endocrine disorders encountered in clinical practice. It is the hyperglycemic state caused either due to a decrease in insulin level or due to decreased peripheral utilization of glucose. It is a multisystem disease that requires optimization before elective surgery. The important considerations are mentioned below.
Preoperative
Sugar control: Fasting less than 140 mg/dL and postprandial less than 180 mg/dL can be accepted for surgery.
Assess complications of diabetes.
Microvascular complications include:
Nephropathy leading to renal failure.
Peripheral neuropathy with risk of foot ulcers, amputations, and Charcot’s joints.
Autonomic neuropathy: Fluctuations in BP, delayed gastric emptying.
The macrovascular complications are:
Omit oral hypoglycemic agents and insulin on the morning of surgery.
On the morning of surgery, measure fasting blood glucose and urine ketones for all patients, and serum potassium if the patient is on insulin.
If autonomic neuropathy is suspected, then give tablet ranitidine and metoclopramide on the night before surgery to prevent any residual food in the stomach.
Intraoperative
May encounter difficult intubation due to stiff joint syndrome (atlantoaxial joint, thyromental joint, and interarytenoid joints).
Avoid dehydration, hypotension, nephrotoxic drugs; judicious use of contrast; hourly urine output monitoring in major cases to prevent acute kidney injury in those already compromised with nephropathy.
Target intraoperative serum glucose between 120 and 200 mg/dL. Blood sugars beyond 200 will lead to glycosuria and dehydration.
Avoid hypoglycemia, as its detection may be delayed due to the effect of sedatives, anesthetics, beta blockers, and sympatholytics.
Autonomic neuropathy may lead to labile blood pressure.
Avoid the use of drugs causing sympathetic stimulation and resulting in hyperglycemia such as ketamine, atropine, pancuronium, and desflurane > 6%.
Thyroid Disorder
Hypothyroidism
Hypothyroidism, also known as myxedema, is known to affect 0.5 to 0.8% of the population. The slow and progressive nature of hypothyroidism leads to a gradual slowing of mental and physical activities in the long term. It can have a myriad of end-organ effects that need to be identified and optimized wherever possible.
Preoperative
If the patient is clinically hypothyroid or thyroid-stimulating hormone (TSH) value increased (however, a slight increase may be taken for surgery), surgery to be deferred. Any change in dose of thyroxin, wait up to 3 weeks for repeat TSH.
These patients are sensitive to the depressive effects of sedatives; so alprazolam premedication is generally not indicated.
Gastric emptying may be delayed; tablet metoclopramide and ranitidine is indicated one night before surgery.
Associations such as hyponatremia, bradycardia, anemia, mental slowing, hypoglycemia, etc., must be noted and corrected wherever possible.
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