Which diagnostic test is primarily used to assess pituitary function related to diabetes insipidus?

The urine osmolality test is crucial in assessing pituitary function, particularly in relation to diabetes insipidus. This condition is characterized by an inability to concentrate urine due to insufficient levels of the antidiuretic hormone (ADH), which is produced by the pituitary gland.

By measuring the concentration of solutes in the urine, the urine osmolality test helps determine how well the kidneys are responding to ADH. In cases of diabetes insipidus, urine osmolality is typically low, indicating that the kidneys are excreting large volumes of diluted urine due to the lack of sufficient ADH action.

While other tests like blood tests for hormones can provide insights into overall hormone levels, and an electrolyte panel can offer information about the chemical balance in the body, they do not specifically assess the kidney's ability to concentrate urine in response to ADH. A CT scan may be useful for imaging purposes but doesn't directly assess pituitary function related to diabetes insipidus. Hence, the urine osmolality test stands as the primary diagnostic tool for evaluating pituitary function in this context.