A nurse is reviewing laboratory results of a client who has atrial fibrillation and is taking warfarin. For which of the following results should the nurse notify the provider?

Choice A reason: Taking the medication in the morning is not the correct instruction. Simvastatin is a statin drug that lowers cholesterol levels by inhibiting the enzyme that produces cholesterol in the liver. The liver produces more cholesterol at night, so simvastatin is more effective when taken in the evening or at bedtime.

Choice B reason: Avoiding grapefruit juice is the correct instruction. Grapefruit juice can increase the blood levels of simvastatin and cause serious side effects such as muscle damage, liver damage, and kidney failure. Grapefruit juice inhibits the enzyme that metabolizes simvastatin in the intestine, leading to higher concentrations of the drug in the bloodstream.

Choice C reason: Monitoring for ringing in the ears is not the correct instruction. Ringing in the ears, or tinnitus, is not a common or serious side effect of simvastatin. However, some other medications that lower cholesterol, such as niacin and gemfibrozil, can cause tinnitus. The client should report any unusual or persistent symptoms to the prescriber.

Choice D reason: Expecting brown-colored urine is not the correct instruction. Brown-colored urine, or hematuria, is not a normal or expected side effect of simvastatin. However, it may indicate a serious condition such as rhabdomyolysis, which is a rare but life-threatening complication of statin therapy. Rhabdomyolysis is the breakdown of muscle tissue that releases a protein called myoglobin into the bloodstream. Myoglobin can damage the kidneys and cause brown-colored urine. The client should seek immediate medical attention if they notice any signs of rhabdomyolysis, such as muscle pain, weakness, fever, or dark urine.

Choice A reason: Distended neck veins is not a manifestation of acute hemolytic reaction, but it may indicate fluid overload, which is another possible complication of blood transfusion. Fluid overload may occur when the blood volume or rate of infusion exceeds the client's circulatory capacity. Fluid overload may manifest as dyspnea, crackles, edema, hypertension, or tachycardia.

Choice B reason: Client report of low back pain is a manifestation of acute hemolytic reaction, which is a life-threatening condition that occurs when the donor blood is incompatible with the recipient's blood. Acute hemolytic reaction may occur within minutes or hours of the transfusion and may cause the destruction of the transfused red blood cells. Acute hemolytic reaction may manifest as fever, chills, low back pain, hemoglobinuria, hypotension, or shock.

Choice C reason: A productive cough is not a manifestation of acute hemolytic reaction, but it may indicate a respiratory infection, which is a potential risk of blood transfusion. Blood transfusion may transmit infectious agents, such as bacteria, viruses, or parasites, from the donor to the recipient. A productive cough may also be a sign of pulmonary edema, which may result from fluid overload or transfusion-related acute lung injury (TRALI).

Choice D reason: Client report of tinnitus is not a manifestation of acute hemolytic reaction, but it may indicate ototoxicity, which is a possible adverse effect of some medications, such as aminoglycosides, loop diuretics, or salicylates. Ototoxicity may damage the inner ear or the auditory nerve and cause hearing loss, tinnitus, or vertigo. The nurse should assess the client's medication history and monitor the client's hearing function.