Final answer:
The highest priority nursing action in responding to tumor lysis syndrome (TLS) in a client with cancer following chemotherapy is to maintain intravenous therapy.
Step-by-step explanation:
The highest priority nursing action in responding to the symptoms of tumor lysis syndrome (TLS) in a client with cancer following chemotherapy would be to maintain intravenous therapy. TLS is a potentially life-threatening condition that occurs when cancer cells release their contents into the bloodstream, leading to the accumulation of metabolic waste products and electrolyte imbalances. Intravenous therapy, particularly hydration with fluids, helps to prevent further complications by promoting the excretion of these waste products and maintaining a balance of electrolytes in the body.