Lab test for patient on warfarin

 # A patient on warfarin sodium following myocardial infarction reports for an oral surgical procedure. Which one of the following laboratory tests should be preferred to ascertain the fitness? 

a. Prothrombin time 

b. Torniquet time 

c. clotting time 

d. bleeding time 

The correct answer is A. Prothrombin time.

The PT and INR tests measure the time it takes for blood to clot by forming thrombin. They evaluate the extrinsic and common coagulation pathways, screening for the presence or absence of fibrinogen (F I), prothrombin (F II), and F V, F VII, and F X. The normal range of PT is approximately 11–13 seconds. Because of individual laboratory reagent variability and the desire to be able to reliably compare the PT from one laboratory with that from another, the PT test is commonly reported with the INR. The INR, introduced by the World Health Organization in 1983, is the ratio of PT that adjusts for the sensitivity of the thromboplastin reagents, such that a normal coagulation profile is reported as an INR of 1.0, and higher values indicate abnormal coagulation. Its most common use is to measure the effects of VKAs and reduction of the vitamin K–dependent F II, F VII, F IX, and F X. It is not effective for hemophilias A and B, since it does not measure F VIII or F IX. Although most patients on VKAs are monitored by monthly venous blood draws and laboratory analysis, the CoaguChek system allows Clinical Laboratory Improvements Amendments (CLIA)-waived point-of-care PT/INR testing of fingerstick blood in physicians’ and dentists’ offices.

Bremsstrahlung refers to:

 # Bremsstrahlung refers to: 

a. the primary source of X-rays from an X-ray tube 

b. Characteristic radiation emitted when an electron is displaced from the outer shell of a tungsten atom in the target 

c. the electromagnetic spectrum 

d. particulate radiation 

The correct answer is: A. a. the primary source of X-rays from an X-ray tube. 

BREMSSTRAHLUNG RADIATION: The sudden stopping or slowing of high-speed electrons by tungsten nuclei in the target produces bremsstrahlung photons, the primary source of radiation from an x-ray tube. (Bremsstrahlung means “braking radiation” in German.)

Multiple punched out radiolucencies is a feature of:

 # Multiple punched-out radiolucencies is a feature of: 

a. Multiple Myeloma 

b. Thalassemia 

c. Fibrous Dysplasia 

d. Ewing's Sarcoma 

The correct answer is A. Multiple myeloma.

The periphery of multiple myeloma lesions is well-defined but not corticated; it lacks any sign of bone reaction. The lesions have been described as appearing “punched out.” However, many appear ragged and even infiltrative. Some lesions have an oval or cystic shape. Untreated or aggressive areas of destruction may become confluent, giving the appearance of multilocularity.

Bleeding time is prolonged in:

 # Bleeding time is prolonged in:

A. Hemophilia

B. Von willebrand disease

C. Telangiectasia

D. Henoch Schonlein purpura 

The correct answer is B. Von Willebrand disease.

Von Willebrand disease (VWD) is the most common hereditary blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions. It arises from a deficiency in the quality or quantity of von Willebrand factor (VWF), a multimeric protein that is required for platelet adhesion. It is known to affect several breeds of dogs as well as humans. The three forms of VWD are hereditary, acquired, and pseudo or platelet type. The three types of hereditary VWD are VWD type 1, VWD type 2, and VWD type 3. Type 2 contains various subtypes. Platelet type VWD is also an inherited condition.

The various types of VWD present with varying degrees of bleeding tendency, usually in the form of easy bruising, nosebleeds, and bleeding gums. Women may experience heavy menstrual periods and blood loss during childbirth.

Severe internal bleeding and bleeding into joints are uncommon in all but the most severe type, VWD type 3.