Which laboratory test measures the effectiveness of warfarin?
PTT.
PT/INR.
aPTT.
ACT.
The Correct Answer is B
PT stands for prothrombin time, which is a measure of how long it takes the blood to clot.
INR stands for international normalized ratio, which is a way of standardizing the PT results across different laboratories.
Warfarin is a blood thinner that works by inhibiting the production of vitamin K-dependent clotting factors in the liver.
Therefore, warfarin prolongs the PT and increases the INR. The PT/INR test is used to monitor the effectiveness of warfarin therapy and adjust the dose accordingly.
Choice A is wrong because PTT stands for partial thromboplastin time, which is another measure of blood clotting time, but it reflects the activity of different clotting factors than PT. PTT is used to monitor heparin therapy, not warfarin therapy.
Choice C is wrong because aPTT stands for activated partial thromboplastin time, which is a variation of PTT that uses an activator to speed up the clotting time. Like PTT, aPTT is used to monitor heparin therapy, not warfarin therapy.
Choice D is wrong because ACT stands for activated clotting time, which is a measure of the whole blood clotting time. ACT is used to monitor high-dose heparin therapy during certain procedures, such as cardiac bypass surgery or angioplasty.
The normal ranges for these tests may vary depending on the laboratory and the method used, but generally, they are:
• PT: 10 to 13 seconds
• INR: 0.8 to 1.2 (without warfarin) or 2.0 to 3.0 (with warfarin)
• PTT: 25 to 35 seconds
• aPTT: 30 to 40 seconds
• ACT: 70 to 120 seconds
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Correct Answer is D
Explanation
Anticoagulant drugs are medicines that prevent blood clots from forming or growing larger.
They do not dissolve existing clots or transport platelets. They work by interfering with different steps of the blood coagulation pathway, which is the process that leads to clot formation.
Choice A is wrong because anticoagulant drugs do not dissolve existing clots.
To dissolve clots, you need fibrinolytic drugs, which break down the fibrin mesh that holds the clots together.
Choice B is wrong because anticoagulant drugs do not transport platelets.
Platelets are blood cells that stick together to form clots.
Anticoagulant drugs may affect the function of platelets, but they do not move them around.
Choice C is wrong because anticoagulant drugs do not act as fibrinolytic agents.
Fibrinolytic agents are drugs that activate plasmin, an enzyme that breaks down fibrin.
Anticoagulant drugs may inhibit the formation of fibrin, but they do not break it down.
Some examples of anticoagulant drugs are warfarin, heparin, and factor Xa inhibitors.
The normal ranges for some blood tests that measure the effects of anticoagulants are:
• Prothrombin time (PT): 11 to 13.5 seconds
• International normalized ratio (INR): 0.8 to 1.2
• Activated partial thromboplastin time (aPTT): 25 to 35 seconds
Correct Answer is B
Explanation
Diuretics are drugs that increase the amount of urine and salt (sodium) excreted by the kidneys. They are used to treat high blood pressure, heart failure, and edema (fluid retention). However, some diuretics can cause low levels of potassium in the blood (hypokalemia), which can lead to muscle weakness, cramps, and arrhythmias. To prevent this, a combination of diuretics acting on different parts of the kidney (such as a loop diuretic and a thiazide diuretic) may be prescribed.This way, the potassium-sparing effect of one diuretic can balance the potassium-wasting effect of the other, while still achieving a net sodium loss.
Choice A is wrong because they are not a part of the initial diuretic therapy.Combination diuretic therapy is usually reserved for patients who are resistant to or intolerant of monotherapy.
Choice C is wrong because little follow up is not needed after the initial treatment.Patients on combination diuretic therapy require close monitoring of their blood pressure, electrolytes, renal function, and weight to avoid adverse effects such as dehydration, hyponatremia, hypotension, and worsening renal function.
Choice D is wrong because they do not increase the risk of hypokalemia.As explained above, combination diuretic therapy aims to reduce the risk of hypokalemia by using a potassium-sparing diuretic along with a potassium-wasting diuretic.
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