What hormone is most likely to be low in the early postoperative period after a splenectomy?

Prolactin is Most Likely to Be Low in the Early Postoperative Period After Splenectomy

In the early postoperative period following splenectomy for trauma, prolactin (Option C) is the hormone most likely to be low, as the acute stress response and surgical trauma typically suppress prolactin secretion while simultaneously elevating counter-regulatory hormones including insulin, glucagon, and vasopressin.

Physiological Response to Major Abdominal Surgery and Trauma

Counter-Regulatory Hormone Elevation

The surgical stress response following major trauma and laparotomy characteristically involves:

• Insulin levels remain elevated or normal in the immediate postoperative period, particularly when glucose infusions are administered and as part of the metabolic stress response 1
• Glucagon levels increase as a counter-regulatory hormone in response to surgical stress and trauma, promoting hepatic glucose production 1
• Vasopressin (ADH) levels rise significantly in response to hypovolemia from massive bleeding, surgical stress, and the body's attempt to maintain intravascular volume 1

Prolactin Suppression During Acute Stress

• Prolactin secretion is characteristically suppressed during acute surgical stress and major trauma, distinguishing it from other pituitary hormones that typically increase during the stress response
• The acute phase response prioritizes counter-regulatory and stress hormones (cortisol, catecholamines, glucagon, vasopressin) over reproductive and metabolic hormones like prolactin

Specific Considerations for This Clinical Scenario

Massive Hemorrhage and Fluid Shifts

• Vasopressin elevation is particularly pronounced in this patient given the massive intra-abdominal bleeding, as ADH is released in response to hypovolemia and hypotension 1
• Fluid resuscitation protocols emphasize maintaining adequate hydration and replacing blood loss, which further stimulates vasopressin release 1

Postoperative Glucose Management

• Hyperglycemia is expected in the early postoperative period following major abdominal surgery and trauma, with guidelines recommending glucose targets of 100-180 mg/dL (5.6-10.0 mmol/L) 1, 2
• Both insulin and glucagon levels remain elevated as part of the stress-induced hyperglycemic response 1
• The surgical stress and counter-regulatory hormone release increase the risk of hyperglycemia, requiring careful glucose monitoring 1

Long-Term Metabolic Considerations

While not directly relevant to the immediate postoperative period, it's worth noting:

• Splenectomy has been associated with increased risk of long-term hyperglycemia and type II diabetes in trauma patients, with studies showing a 2-fold higher risk after 3 years 3, 4
• This suggests the spleen may play a role in glucose homeostasis, though the mechanism remains under investigation 3, 5, 4

Clinical Pitfalls to Avoid

• Do not confuse chronic hormonal changes with acute postoperative responses - the question specifically asks about the early postoperative period, not long-term sequelae
• Remember that stress hormones (including insulin, glucagon, and vasopressin) are elevated during acute surgical stress, while prolactin is suppressed
• Monitor glucose levels closely in the postoperative period, as hyperglycemia increases morbidity and mortality risk, particularly infections 1