A client has ABGs: pH 7.48, PaCO2 30 mmHg, HCO3 29 mEq/L. Which condition is most likely?

Choice A rationale

Glucagon levels are actually elevated in diabetic ketoacidosis, as the body perceives a state of starvation because glucose cannot enter the cells. This hormonal imbalance promotes gluconeogenesis and glycogenolysis, worsening hyperglycemia. Furthermore, the condition described is metabolic acidosis, characterized by a low pH of 7.25 and a low bicarbonate of 15 mEq/L, not alkalosis. The fruity breath and rapid Kussmaul respirations are compensatory mechanisms for high acid levels, specifically the accumulation of volatile ketoacids.

Choice B rationale

This client is experiencing severe hyperglycemia with a blood glucose of 420 mg/dL, which is the opposite of hypoglycemia. In type 1 diabetes, there is an absolute deficiency of insulin production due to the autoimmune destruction of pancreatic beta cells. Without insulin, glucose remains in the bloodstream instead of being used for energy. The symptoms of nausea, vomiting, and fruity breath are classic indicators of ketoacidosis resulting from this lack of insulin, not an overproduction of it.

Choice C rationale

In the absence of insulin, cells cannot uptake glucose for fuel, prompting the body to switch to an alternative energy source by breaking down adipose tissue. This process, known as lipolysis, releases free fatty acids that are converted by the liver into ketones, such as acetoacetate and beta-hydroxybutyrate. Ketones are acidic, leading to a drop in blood pH below the normal range of 7.35 to 7.45. The fruity odor is caused by acetone, a byproduct of this metabolic pathway.

Choice D rationale

Aldosterone is a mineralocorticoid that regulates sodium and potassium balance, but it is not the primary driver of diabetic ketoacidosis. While electrolyte imbalances occur in this condition due to osmotic diuresis, the fundamental pathophysiology is a metabolic shift caused by insulin deficiency. Sodium retention is not the cause of the fruity breath, rapid respirations, or the significant drop in bicarbonate. The focus remains on the metabolic acidosis produced by the excessive accumulation of ketones from lipid metabolism. .

Choice A rationale

The activation of macrophages is primarily a function of T helper cells, specifically the Th subset. These T cells release cytokines such as interferon-gamma, which enhances the phagocytic and microbicidal activity of macrophages. While B cells are part of the adaptive immune system and can act as antigen-presenting cells, their primary specialized role in the immune hierarchy is not the direct stimulation of macrophage effector functions but rather the transition into antibody-secreting plasma cells.

Choice B rationale

The recognition of Major Histocompatibility Complex I molecules is a specific function of CD8+ cytotoxic T lymphocytes. Every nucleated cell in the human body expresses MHC I to display endogenous antigens. Cytotoxic T cells use their T-cell receptors to scan these molecules for viral or tumor proteins. B cells, conversely, recognize intact, soluble antigens through their membrane-bound immunoglobulin receptors, which do not require the antigen to be presented on an MHC I molecule for initial binding.

Choice C rationale

The direct killing of infected or cancerous cells is performed by cytotoxic T cells and Natural Killer cells through the release of perforins and granzymes. These substances induce apoptosis in the target cell. B cells do not possess these cytolytic granules and do not engage in cell-to-cell combat. Instead, they provide humoral immunity, which involves the systemic distribution of proteins that neutralize pathogens remotely, rather than requiring the B cell to physically destroy the infected host cell.

Choice D rationale

The hallmark function of B lymphocytes is their differentiation into plasma cells, which are specialized factories for the production of antibodies or immunoglobulins. These antibodies circulate in the blood and lymph, binding specifically to antigens on the surface of pathogens like bacteria and viruses. This binding can neutralize the pathogen, opsonize it for easier phagocytosis by neutrophils, or activate the complement system. This humoral response is essential for long-term immunity and the effectiveness of vaccinations.