When collecting a capillary blood specimen for bilirubin from a newborn receiving phototherapy for jaundice, it is especially important to turn off the phototherapy light during collection because exposure of the blood sample to the light may break down the bilirubin. The specimen must be obtained carefully to prevent hemolysis and placed in an amber microcollection container, or the container should be covered with aluminum foil to protect the contents from light The blood specimen should be collected as soon after the request as possible because accurate timing can help to determine the rate of bilirubin increase.

During venipuncture, if the needle appears to be in the vein but no blood is flowing and a slight vibration or quiver of the needle is noted, the most appropriate initial response is to remove the vacuum tube, pull back slightly on the needle, and reinsert the vacuum tube. If this is not successful, the venipuncture should be discontinued and another site attempted. The lack of blood flow and vibration or quiver suggest that the needle is in a valve and the valve is attempting to open and close.

The symbols for less than (<) and greater than can be confused for the letter L and the number 7, respectively, especially when hand-written. The Institute for Safe Medication Practices (ISMP) put these symbols on their "List of Error-Prone Abbreviations, Symbols, and Dose Designations" and recommends using "less than" or "greater than" instead.

The hydrogen breath test is most often used to test for lactose intolerance. Typically, exhaled breath contains very little hydrogen. However, if there is a problem with the digestion of lactose or other carbohydrates (such as fructose), bacteria in the colon ferment the carbohydrates, and this produces hydrogen. The hydrogen is absorbed into the systemic circulation and sent to the lungs, then it is exhaled. Higher than normal levels of hydrogen suggest a problem with carbohydrate metabolism.