Which of the following is an appropriate technique when preparing a site for venipuncture after applying antiseptic?

Choice A reason:
Chilling the sample is the correct method for preparing a lactic acid sample for processing and transportation. Lactic acid levels can continue to change after the blood is drawn due to ongoing cellular metabolism. Chilling the sample slows down this metabolism, preserving the accuracy of the lactic acid measurement. The sample should be placed on ice or in a refrigerated environment as soon as possible after collection.

Choice B reason:
While protecting the sample from light is important for some types of specimens, it is not the primary concern for lactic acid samples. The key factor for lactic acid stability is temperature control, not light exposure. Therefore, while it may be beneficial to keep the sample out of direct sunlight, chilling it is the priority to prevent changes in lactic acid levels.

Choice C reason:
Attaching a heat block to the sample is not a recommended method for lactic acid samples. Heat can increase metabolic activity, potentially altering the lactic acid levels in the sample. This would lead to inaccurate results, as the goal is to preserve the state of the sample at the time of collection.

Choice D reason:
Freezing the sample is not typically recommended for immediate processing and transportation of a lactic acid sample. While freezing can preserve certain types of specimens for long-term storage, it is not necessary for short-term transport and can cause issues such as hemolysis, which may interfere with the test results.

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.