A nurse is reinforcing teaching with a client who is recovering from gastroenteritis and is beginning oral intake. Which of the following foods should the nurse recommend?

Palpable area of induration, greater than 10 mm (0.4 in) in diameter. This indicates a positive tuberculin skin test (TST) reaction for a person with no known risk factors for TB infection. A positive TST reaction means that the person has been infected with Mycobacterium tuberculosis, the bacterium that causes TB disease, and needs further testing to confirm the diagnosis and rule out active TB disease.

The other choices are not correct because:

- Choice A. Nonpalpable area of redness, less than 5 mm (0.2 in) in diameter. This indicates a negative TST reaction for any person, regardless of their risk factors for TB infection. A negative TST reaction means that the person has not been infected with Mycobacterium tuberculosis or has a very low level of immune response to the bacterium.

- Choice B. Area of ecchymosis, greater than 12 mm (0.5 in) in diameter. This indicates a bruise or bleeding under the skin, not a TST reaction. Ecchymosis is not caused by the injection of tuberculin purified protein derivative (PPD) into the skin, but by trauma or injury to the blood vessels.

- Choice C. Tenderness at the injection site. This indicates a mild local reaction to the injection of tuberculin PPD into the skin, not a TST reaction. Tenderness is not measured in millimeters of induration (firm swelling), which is the standard way of reading TST results.

The correct answer is choice B: Store opened insulin vials at room temperature for up to 4 weeks.

Choice B rationale: Opened insulin vials can be stored at room temperature (59°F to 86°F or 15°C to 30°C) for up to 4 weeks. After this period, the insulin may lose potency, and a new vial should be used.

Choice A rationale: Regular insulin is short-acting, and its peak effect occurs 2 to 3 hours after administration. Eating a snack 6 hours after insulin administration may not be necessary as the insulin would have already reached its peak effect, and blood glucose levels should be monitored accordingly.

Choice C rationale: Warming the insulin vial to dissolve crystals is not recommended. Insulin should be inspected before use, and if crystals or clumps are present, it should be discarded as this could indicate that the insulin has lost its effectiveness.

Choice D rationale: Unopened insulin vials should be stored in the refrigerator (36°F to 46°F or 2°C to 8°C) and should not be frozen. Freezing can cause insulin to lose potency or become ineffective. Once opened, insulin vials can be stored at room temperature for up to 4 weeks, as mentioned in choice B.