A phlebotomist should instruct a patient to take which of the following actions when providing a sputum specimen?

Choice A reason:
The BUN test measures the amount of urea nitrogen in the blood, which can indicate kidney function. Fasting is not typically required for a BUN test unless it is being conducted alongside other tests that may require fasting.

Choice B reason:
An HDL test is part of a lipid profile that measures the levels of good cholesterol in the blood. Fasting before a cholesterol test, including HDL, is often recommended to ensure accuracy, although recent guidelines have changed, allowing for nonfasting cholesterol testing in certain individuals.

Choice C reason:
An ABG test measures oxygen and carbon dioxide levels in the blood and assesses the body's acid-base balance. Preparation for an ABG test does not typically require fasting, but patients may need to stop supplemental oxygen before the test to get accurate measurements.

Choice D reason:
A CBC test, or complete blood count, does not require fasting. It measures various factors of the blood, including red and white blood cells and platelets. Fasting is not necessary unless the CBC is part of a panel of tests that includes tests requiring fasting.

Choice A reason:
The Apgar score is a quick test performed on a newborn at 1 and 5 minutes after birth. The 1-minute score determines how well the baby tolerated the birthing process. The 5-minute score tells the healthcare provider how well the baby is doing outside the mother's womb. While it is an important indicator of a newborn's health, it does not directly influence the calculation of total blood volume.

Choice B reason:
Height is a measure of the length of a person's body. In the context of a 2-day-old infant, height is not a practical or necessary measurement for determining blood volume. Blood volume is more closely related to weight than to height, especially in the case of infants.

Choice C reason:
Head circumference is a measurement of the size of a child's head and is used to monitor brain growth. While it can provide valuable information about a child's development, it is not used to calculate blood volume. The total blood volume of an infant is not determined by the size of the head but rather by the overall weight.

Choice D reason:
Weight is the correct factor to consider when calculating total blood volume for a full-term, 2-day-old infant. The standard formula to estimate an infant's total blood volume is approximately 80 {mL/kg} of body weight. Therefore, knowing the infant's weight in kilograms is essential for this calculation.