A home health nurse is visiting a client who has heart failure and a prescription for furosemide. The nurse identifies that the client has gained 2.5 kg (5 lb) since the last visit 2 days ago. Which of the following actions should the nurse take first?

A. Notify the provider of the client's weight gain: While the provider must be informed, the nurse should first assess the cause of the weight gain. Immediate notification without understanding the client's adherence to treatment may delay identifying a correctable issue. B. Teach the client about foods low in sodium: Dietary education is important in managing heart failure, but it is not the priority action when the client presents with significant weight gain over a short period, which may indicate fluid retention. C. Encourage the client to dangle the legs while sitting in a chair: This may help with comfort if the client is experiencing edema, but it does not address the root cause of the sudden weight gain and is not a priority intervention in managing fluid overload. D. Determine medication adherence by the client: A weight gain of 2.5 kg (5 lb) in 2 days suggests significant fluid retention. The nurse should first assess whether the client has been taking furosemide as prescribed, as nonadherence could directly explain the symptom and guide further actions.