A client with metabolic alkalosis secondary to prolonged vomiting is at highest risk for which electrolyte imbalance?

Choice A rationale

Restricting fluids would be contraindicated in a patient with adrenal insufficiency experiencing hypotension. These patients suffer from a profound deficit of mineralocorticoids, specifically aldosterone, which leads to massive urinary loss of sodium and water. Normal serum sodium is 135 to 145 mEq/L. The resulting hypovolemia requires aggressive fluid resuscitation with isotonic saline to restore circulating volume and blood pressure. Fluid restriction would worsen the cardiovascular collapse and exacerbate the Addisonian crisis.

Choice B rationale

Providing potassium supplements is dangerous because hyperkalemia is already present in adrenal insufficiency. Normal serum potassium is 3.5 to 5.0 mEq/L. Without aldosterone, the kidneys cannot effectively excrete potassium in exchange for sodium. Adding more potassium would increase the risk of life threatening cardiac arrhythmias or cardiac arrest. The clinical goal is to lower the potassium levels through volume expansion and corticosteroid replacement rather than increasing the total body potassium load.

Choice C rationale

Administering insulin is a temporary measure used to shift potassium from the extracellular fluid into the intracellular compartment. While it addresses the hyperkalemia, it does not treat the underlying cause of the crisis, which is a lack of cortisol and aldosterone. Furthermore, patients in adrenal crisis are often hypoglycemic due to glucocorticoid deficiency. Giving insulin without dextrose could cause fatal hypoglycemia. It is not the primary priority compared to replacing the missing hormones.

Choice D rationale

Administering intravenous hydrocortisone is the priority intervention because it provides both glucocorticoid and mineralocorticoid activity. This replacement therapy addresses the underlying hormonal deficit, helping to restore vascular tone, increase blood glucose levels, and promote the renal retention of sodium and excretion of potassium. By correcting the hormonal imbalance, hydrocortisone stabilizes the hemodynamics and electrolyte disturbances. This intervention is essential to reverse the life threatening systemic effects of an acute adrenal or Addisonian crisis.

Choice A rationale

While metabolic acidosis and electrolyte imbalances can lower the seizure threshold, they are not the most immediate life-threatening concern in this laboratory profile. Seizures are more commonly associated with acute changes in sodium levels or severe uremia. Given the provided potassium level, the neurological system is less of a priority than the cardiovascular system, as the electrical stability of the heart is currently under significant threat from the elevated extracellular potassium and the acidic environment.

Choice B rationale

The client has a potassium level of 5.8 mEq/L, which exceeds the normal range of 3.5 to 5.0 mEq/L. Hyperkalemia, combined with a pH of 7.25, significantly increases the risk of lethal cardiac dysrhythmias. Acidosis causes a shift of potassium from the intracellular to the extracellular space, worsening the hyperkalemia. These high levels decrease the resting membrane potential of cardiac cells, leading to peaked T waves, widened QRS complexes, and potentially ventricular fibrillation or asystole.

Choice C rationale

The patient is currently experiencing metabolic acidosis, not respiratory acidosis. This is evidenced by the low pH of 7.25 and a low bicarbonate level of 16 mEq/L, while the PaCO2 is 36 mmHg, which is within the normal range of 35 to 45 mmHg. Respiratory acidosis would be characterized by a high PaCO2. Because the primary problem is a metabolic failure of the kidneys to excrete acid and regenerate bicarbonate, the respiratory system is not the priority complication.

Choice D rationale

Metabolic alkalosis is characterized by a high pH (greater than 7.45) and an elevated bicarbonate level (greater than 26 mEq/L). This patient’s laboratory values show exactly the opposite: a low pH and a low bicarbonate. Chronic kidney disease leads to the accumulation of hydrogen ions and the loss of bicarbonate, resulting in metabolic acidosis. Prioritizing alkalosis would be a clinical error as it contradicts the physiological state indicated by the arterial blood gas results.