After a hypophysectomy, which finding may indicate that diabetes insipidus is developing?

After a hypophysectomy, a low urine specific gravity indicates that diabetes insipidus may be developing. This condition is characterized by an inability of the body to concentrate urine due to a deficiency of antidiuretic hormone (ADH), often resulting from damage to the pituitary gland during surgery.

In a healthy individual, ADH regulates water balance by making the kidneys retain water, which results in concentrated urine and a higher specific gravity. Conversely, when ADH levels are low—as can happen following a hypophysectomy—the kidneys fail to retain sufficient water, leading to the production of dilute urine. This results in a low urine specific gravity, signifying that the urine is more diluted than normal.

Therefore, monitoring urine specific gravity is crucial in the post-operative period, as it serves as an early indicator of diabetes insipidus and helps guide further diagnostic and therapeutic interventions. Increased thirst may also be a symptom of diabetes insipidus, but urine specific gravity provides more direct information about kidney function in this context.