A client receives a 12-lead electrocardiogram (ECG) and asks the practical nurse (PN) what the test is measuring. Which information should the PN explain about this diagnostic test?

Choice A reason: Aldosterone is a hormone produced by the adrenal cortex that helps regulate sodium and potassium levels in the body. While aldosterone levels can indicate adrenal function, they are not as commonly used as cortisol levels in diagnosing adrenal cortex failure. Aldosterone regulation is also influenced by the renin-angiotensin-aldosterone system, making it a less direct indicator of overall adrenal cortex function compared to cortisol.
Choice B reason: Cortisol is a glucocorticoid hormone produced by the adrenal cortex and plays a vital role in regulating metabolism, immune response, and stress. Measuring cortisol levels is a primary method for assessing adrenal cortex function. Low cortisol levels can indicate adrenal insufficiency or failure, such as in conditions like Addison's disease. Evaluating cortisol levels provides a direct assessment of the adrenal gland’s ability to produce essential hormones necessary for the body's normal functioning.
Choice C reason: Thyroxine (T4) is a hormone produced by the thyroid gland, not the adrenal cortex. It plays a crucial role in regulating metabolism, growth, and development. While thyroxine levels are important for thyroid function assessment, they do not directly reflect the functioning of the adrenal gland. Therefore, thyroxine levels are not relevant in diagnosing adrenal cortex failure.
Choice D reason: Insulin is a hormone produced by the pancreas and is essential for regulating blood glucose levels. It is not related to the adrenal cortex. Monitoring insulin levels is important for diagnosing and managing diabetes mellitus but does not provide information about the functioning of the adrenal gland. Insulin levels are not used to assess adrenal cortex function.

Choice A reason: Lymph nodes are important components of the immune system and play a crucial role in filtering harmful substances and housing lymphocytes. While HIV/AIDS can affect lymph nodes, it is not the primary target of the virus.
Choice B reason: The spleen is another vital organ in the immune system that helps filter blood and fight infections. However, it is not the specific target of HIV.
Choice C reason: T cells, specifically CD4+ T cells, are the main target of HIV (the virus that causes AIDS). HIV infects and destroys these cells, leading to a weakened immune system. The progressive loss of CD4+ T cells impairs the body's ability to fight off infections and certain cancers, which is characteristic of AIDS.
Choice D reason: B cells are responsible for producing antibodies and play a key role in the humoral immune response. While HIV/AIDS can indirectly impact B cell function due to the overall compromised immune system, B cells are not the primary cells affected by the virus.