The clinical manifestations are mainly weakness, drowsiness, depression, loss of appetite, nausea, vomiting, etc. Most patients have hypochlorhydria, some have hypokalemia, and most patients have transient hyponatremia.
Late hyponatremia after pituitary adenoma surgery is related to the type of pathology, tumor size, patient age, and blood and urine cortisol levels.
The incidence of hyponatremia is significantly higher in patients with non-functioning pituitary adenomas and ACTH adenomas than in patients with all other types of pituitary adenomas, which may be related to the fact that patients with non-functioning adenomas are more likely to have large adenomas at the time of presentation and are more likely to have combined hypopituitary function.
The incidence of postoperative hyponatremia is higher in patients with pituitary macroadenomas and giant adenomas than in patients with pituitary microadenomas, which may be related to the greater impact of macroadenomas on pituitary function even before surgery, the fact that some patients have preoperative hypopituitary function, and the fact that surgical trauma to macroadenomas causes further damage to the remaining normal pituitary tissue.
The incidence of postoperative hyponatremia is significantly higher in elderly patients over 50 years of age than in patients of all other age groups, and is mostly moderate or severe. This may be due to the poor compensatory capacity of the pituitary gland in elderly patients, which predisposes them to postoperative pituitary dysfunction, thus causing water-electrolyte disturbances. Therefore, hyponatremic conditions are usually not self-adjusting and require the administration of medications to correct them.
Postoperative uremia after pituitary adenoma is due to injury to the posterior pituitary lobe or pituitary stalk. In the author’s opinion, minimizing damage to normal pituitary tissue and stretching of the pituitary stalk during surgery is particularly important to reduce the occurrence of postoperative uroemesis. The operator should carefully distinguish the residual pituitary tissue by color and texture during surgery to minimize damage to pituitary tissue on the basis of maximum tumor removal. Neuroendoscopic surgery has some advantages in this regard, with a larger intraoperative field of view and the possibility of scraping the tumor under direct vision in most cases, whereas microscopic surgery needs to rely on the operator’s experience in terms of handedness.
With appropriate pituitary adenoma surgery, postoperative uveitis is usually transient and mild. Mild uremia may be managed without medication and with appropriate water restriction; moderate or greater uremia may be treated with oral carbamazepine or desmopressin acetate tablets, and posterior pituitary hormone. Clinical attention should be paid to the fact that overdose of antidiuretics can cause hyponatremia because their antidiuretic function causes more water retention than sodium retention, resulting in medically induced SIADH, so blood electrolytes should be closely monitored when applying antidiuretics.