Cortisol (hydrocortisone) disappearance rate and pathophysiologic changes after bilateral adrenalectomy in equids.

The research studied the changes in the body of six ponies and a horse after bilateral adrenalectomy (removal of both adrenal glands), focusing on the survival rate and how the disappearance rate of cortisol (a hormone produced by the adrenal glands) affects the physiological changes in the body.

Objective and Method

• The main objective of this research was to ascertain the changes in equids after bilateral adrenalectomy, targetting primarily on the survival rates, cortisol disappearance rate, and the related physiological alterations in the body.
• For this purpose, the experiment was conducted on six ponies and one horse. These animals were bilaterally adrenalectomized, meaning that both of their adrenal glands were removed.

Findings

• It was discovered that two out of the seven animals managed to survive for 24 and 72 hours, respectively, despite not being provided with any additional corticosteroid supplement. The researchers clarified that the surgical procedure was not the cause of death.
• They determined that the half-life of cortisol in these animals’ bodies was estimated to be around 2.1 +/- 0.6 hours. The cortisol disappearance from their bodies was found to have occurred in two phases; first through a redistribution, followed by the elimination period.

Physiological Changes

• Post-surgery, several pathophysiological changes were noticed in the animals. There was an increase in the serum sodium and chloride in their bodies, along with an increase in PCV (Packed Cell Volume, a measure of the concentration of red blood cells in blood).
• Conversely, the serum potassium of the animals reduced significantly after the surgery.
• These changes have been reported to be consistent with the ones observed in other species post bilateral adrenalectomy.

Electrolyte Clearance

• Additionally, the researchers calculated the clearance of electrolytes in the animals, using the creatinine clearance method – a commonly used method to estimate glomerular filtration rates in kidney function tests.
• Interestingly, it was found that these clearance values exhibited an inverse correlation with the observed changes in serum electrolytes. Thus, as the levels of serum electrolytes increased, the rate of their clearance decreased, suggesting the significant role of the adrenal glands in the body’s electrolyte balance.