How can a phlebotomist distinguish whether a collection tube contains serum or plasma?

Choice A Reason:

Positioning the needle at a 45° angle to the skin is not the recommended approach for venipuncture using a butterfly needle on dorsal hand veins. The correct angle for insertion is usually less than 45°, often around 15-30°, to ensure a shallow entry and reduce the risk of going through the vein.

Choice B Reason:

Holding the needle by the wings of the butterfly is the correct technique. This allows for better control and stability during insertion. The wings are designed to be held between the thumb and forefinger, providing an easy grip for the phlebotomist to maneuver the needle with precision.

Choice C Reason:

Instructing the patient to hold the collection tubes is not standard practice and could lead to pre-analytical errors. The phlebotomist should maintain control of the tubes to ensure proper blood flow and fill volume, as well as to prevent contamination or accidents.

Choice D Reason:

Applying the tourniquet at the antecubital area is not specific to the use of a butterfly needle for venipuncture on dorsal hand veins. While a tourniquet is used to engorge the veins and make them more prominent, its placement may vary depending on the selected puncture site and is not the action in question here.

Choice A reason:
Glucose and triglyceride levels are influenced by recent food intake, so it is essential to measure these levels after a period of fasting to obtain accurate results. Fasting ensures that the glucose measurement reflects the body's baseline glucose level without the influence of a recent meal, which is crucial for diagnosing and managing conditions like diabetes. Similarly, triglycerides, which are fats in the blood, can be elevated after eating, so a fasting sample gives a clear picture of the lipid profile for assessing cardiovascular risk.

Choice B reason:
While BUN (Blood Urea Nitrogen) levels can be affected by diet, fasting is not typically required for BUN or alkaline phosphatase tests. These tests are often part of a comprehensive metabolic panel that may or may not require fasting. However, fasting is not specifically necessary for accurate measurement of these two tests.

Choice C reason:
Creatinine and total protein levels are generally not affected by short-term dietary intake, so fasting is not required for these tests. Creatinine is a waste product from muscle metabolism and is used to evaluate kidney function, while total protein levels can indicate a variety of conditions including liver and kidney disorders, but they reflect the body's long-term nutritional status rather than immediate food intake.

Choice D reason:
Lactate dehydrogenase (LDH) and albumin tests do not require fasting. LDH is an enzyme found in almost all body tissues and is released into the bloodstream when tissues are damaged, so its levels are not dependent on food intake. Albumin is the most abundant protein in the blood and is produced by the liver; its levels are used to assess liver and kidney function, nutritional status, and other conditions, but fasting is not necessary for accurate measurement.