Final answer:
The nurse will assign the nursing diagnosis of Deficient fluid volume to the patient based on the exhibited symptoms.
Step-by-step explanation:
The nursing diagnosis that the nurse will assign to the patient based on the exhibited symptoms is Deficient fluid volume. Tachycardia, increased thirst, decreased urine output, and increased body temperature are all indicative of dehydration or low fluid volume in the body. Headache can also be a symptom of dehydration.