A nurse is assessing a preoperative client. The client has a history of atrial fibrillation and is taking warfarin daily. Which test order will the nurse request from the provider?

A. Troponin is a protein found in cardiac muscle cells. When there is damage to the heart muscle, such as during a myocardial infarction (heart attack), troponin is released into the bloodstream. Therefore, elevated troponin levels in the blood indicate myocardial injury or damage.
B. Troponin is not an enzyme; it is a protein. While there are enzymes such as creatine kinase (CK) and lactate dehydrogenase (LDH) that can indicate damage to various tissues including heart and skeletal muscles, troponin specifically indicates cardiac muscle damage.
C. Troponin is not involved in oxygen transport. Hemoglobin, found in red blood cells, is the protein responsible for oxygen transport in the body.
D. Troponin is not a lipid; it is a protein. Lipids include substances like cholesterol and triglycerides. Troponin levels do not reflect the risk for coronary artery disease; rather, they indicate acute damage to the heart muscle.

A. Postoperative ileus and significant drainage via an NG tube are more likely to lead to electrolyte losses rather than elevated levels. Elevated magnesium levels are less common and typically associated with conditions such as renal failure or excessive magnesium intake.
B. Calcium levels can be affected by gastrointestinal losses, including drainage via an NG tube. Significant fluid loss can lead to hemoconcentration, potentially causing a relative increase in calcium levels initially. However, prolonged fluid loss can lead to overall depletion of electrolytes, including calcium.
C. When fluids are lost through the NG tube, potassium, which is an intracellular electrolyte, can be lost in large amounts. Prolonged drainage can lead to hypokalemia (decreased potassium levels), which can result in muscle weakness, cardiac dysrhythmias, and other serious complications.
D. Elevated sodium levels (hypernatremia) are more commonly associated with dehydration or excessive sodium intake rather than drainage via an NG tube. In this scenario, sodium levels are less likely to be affected compared to potassium.