Correct Answer: A

Rationale: The correct answer is A. Dark, tarry stools may indicate gastrointestinal bleeding, a potentially life-threatening condition that requires immediate attention. Visiting this client first is crucial for prompt assessment and intervention. Choices B, C, and D do not present immediate life-threatening conditions that require urgent attention compared to the potential emergency indicated by dark, tarry stools.

Correct Answer: D

Rationale: The correct answer is D, narrow therapeutic index. Narrow therapeutic index (NTI) drugs are defined as those drugs where small differences in dose or blood concentration may lead to serious therapeutic failures or adverse drug reactions. Choices A, B, and C are not directly related to the risk of drug toxicity. Low bioavailability (Choice A) refers to the amount of drug that enters the bloodstream unchanged after administration. Rapid onset of action (Choice B) and short half-life (Choice C) are characteristics related to drug effectiveness and metabolism but do not necessarily indicate a higher risk of drug toxicity.

Correct Answer: C

Rationale: A serum potassium level of 5.5 mEq/L is concerning in a client with DKA as it may indicate worsening hyperkalemia, requiring immediate intervention. Elevated serum potassium levels can lead to life-threatening cardiac arrhythmias. While elevated glucose and low bicarbonate are characteristic of DKA, hyperkalemia poses a higher immediate risk. Serum sodium within the normal range is not typically a primary concern in DKA.

Correct Answer: C

Rationale: In a client with acute pancreatitis receiving total parenteral nutrition (TPN), the nurse should monitor serum triglycerides closely. Acute pancreatitis can lead to fat malabsorption, making the client susceptible to hypertriglyceridemia. Monitoring serum triglycerides is crucial to prevent complications such as hyperlipidemia. While monitoring serum potassium, glucose, and calcium levels is also essential in various conditions, in this scenario, the primary concern is the risk of developing hypertriglyceridemia due to fat malabsorption.

Correct Answer: D

Rationale: A serum pH of 7.28 indicates metabolic acidosis in a client with diabetic ketoacidosis (DKA), requiring immediate intervention. In DKA, the body produces excess ketones, leading to acidosis. Monitoring and correcting the pH level is crucial in managing DKA. Serum glucose levels may be high in DKA, but the immediate concern is correcting the acidosis to prevent complications. Serum potassium and bicarbonate levels are also important but not as immediately critical as correcting the acidosis in DKA.