A nurse is admitting a client who reports recurrent flank pain and nausea for 24 hr. Which of the following actions should the nurse take first?

A. Monitor intake and output.: Measuring fluid balance is a standard nursing intervention for renal complaints, but it does not address the client's immediate physiological distress. While important for tracking renal function, it is a secondary assessment compared to the management of acute symptoms. Monitoring is a continuous process rather than the priority action for a client in pain. B. Administer pain medication.: The priority for a client with suspected renal colic is to alleviate the intense pain, which also helps reduce associated nausea and sympathetic nervous system activation. Providing analgesic relief is the first step in the "comfort, then diagnostic" hierarchy of care. Once pain is controlled, the client will be more cooperative for further diagnostic procedures and interventions. C. Strain the urine.: Straining urine is essential for capturing calculi for laboratory analysis to determine the stone's chemical composition. However, this is a diagnostic task that follows the stabilization of the client's acute pain and discomfort. Straining urine does not provide immediate therapeutic relief for the flank pain or nausea the client is currently experiencing. D. Ambulate in hall.: Ambulation can help facilitate the passage of a kidney stone through the ureter, but it is contraindicated while the client is experiencing severe pain and nausea. Physical exertion during an acute episode of renal colic can exacerbate the client's distress and increase the risk of falls. Ambulation should only occur once the pain is adequately managed.