Final answer:
Central diabetes insipidus is due to inadequate ADH production from the posterior pituitary, while nephrogenic diabetes insipidus is due to the kidneys not responding to ADH. A water deprivation test can differentiate the two by administering ADH and observing for a change in urine concentration, which will be present in central but absent in nephrogenic diabetes insipidus.
Step-by-step explanation:
The difference between central and nephrogenic diabetes insipidus can be determined using a water deprivation test. Central diabetes insipidus is caused by a chronic underproduction of antidiuretic hormone (ADH), also known as vasopressin, which occurs when the posterior pituitary does not release enough ADH. Consequently, the kidneys are unable to retain water, leading to the production of large volumes of dilute urine. Contrastingly, nephrogenic diabetes insipidus occurs when the kidneys do not respond to ADH, due to a mutation in the ADH receptor or other factors affecting the kidneys' ability to reabsorb water. This condition also results in the excretion of large amounts of dilute urine despite the presence of ADH.
In a water deprivation test, patients with central diabetes insipidus will show an increase in urine concentration after ADH administration since their kidneys are capable of responding to ADH but do not receive enough of it from the posterior pituitary. On the other hand, individuals with nephrogenic diabetes insipidus will not show an increase in urine concentration after ADH administration, indicating a problem with the kidney's response to ADH.