Final answer:
The priority nursing intervention is to instruct the patient not to take any more lithium until directed by the healthcare provider.
Step-by-step explanation:
The priority nursing intervention for a patient with bipolar disorder experiencing symptoms of nausea, vomiting, diarrhea, thirst, hand tremors, and unsteady gait after playing soccer on a hot summer day is to instruct the patient not to take any more lithium until directed by the healthcare provider.
Lithium is a medication commonly prescribed for bipolar disorder, but excessive sweating and dehydration, common during physical activity in hot weather, can cause increased levels of lithium in the blood. This can lead to lithium toxicity, which presents with the symptoms described.
It is important for the patient to discontinue taking lithium until their healthcare provider can evaluate their condition and adjust the dosage, if necessary.