What does the nurse identify as the most common cause of acute kidney injury in a critically ill patient?

Rationale:
A. Fatigue is incorrect because, although patients with diabetes insipidus (DI) may experience fatigue, this symptom is nonspecific. Fatigue can result from many conditions, including dehydration, electrolyte imbalances, chronic illness, or sleep disturbances. In DI, fatigue may develop secondary to fluid and electrolyte loss, but it is not a primary or diagnostic feature of the disorder.

B. Polydipsia is correct because it is the most indicative and classic symptom of DI. Diabetes insipidus results from either a deficiency of antidiuretic hormone (ADH, also called vasopressin) in central DI or the kidneys’ inability to respond to ADH in nephrogenic DI. Without adequate ADH activity, the kidneys cannot concentrate urine, leading to the excretion of large volumes of dilute urine (polyuria), sometimes up to 3–20 liters per day in severe cases. The body attempts to compensate for this fluid loss by triggering intense thirst (polydipsia), often resulting in the patient drinking large amounts of water to prevent dehydration. Polydipsia is thus a hallmark symptom and a key diagnostic clue for DI.

C. Weight gain is incorrect because the fluid loss associated with DI typically causes weight loss rather than gain. Patients may have decreased body mass due to the ongoing loss of water and potential electrolyte depletion. Weight gain is not associated with DI unless there is excessive water intake beyond renal capacity, which is uncommon.

D. Diarrhea is incorrect because DI affects renal water reabsorption, not gastrointestinal function. Diarrhea is unrelated to the pathophysiology of DI and may indicate a separate gastrointestinal issue rather than the endocrine disorder itself.

Rationale:

A. The liver is the primary organ for glycogen storage and gluconeogenesis, which maintain blood glucose during fasting or stress. In end-stage liver disease (ESLD), these processes are impaired due to hepatocellular dysfunction, resulting in low blood glucose levels. Hypoglycemia can contribute to weakness, confusion, or even hepatic encephalopathy, making it an expected clinical finding.

B. DIC is not typically associated with ESLD. DIC is a systemic disorder of clotting and fibrinolysis, leading to widespread microthrombi formation and simultaneous bleeding. While patients with ESLD do have coagulopathy due to impaired synthesis of clotting factors and thrombocytopenia, this does not cause the generalized activation of coagulation seen in DIC. If DIC were present in a patient with ESLD, it would usually indicate a secondary condition, such as sepsis, trauma, or severe infection, rather than the liver disease itself.

C. Ascites is a common and expected finding in ESLD, primarily caused by portal hypertension and hypoalbuminemia. Increased hydrostatic pressure in the portal circulation forces fluid into the peritoneal cavity, while low plasma oncotic pressure from reduced albumin worsens fluid accumulation. Patients may present with abdominal distension, shifting dullness, or fluid wave.

D. Malnutrition is frequent in ESLD due to decreased appetite, impaired nutrient absorption, altered metabolism, and early satiety from ascites. Patients often show muscle wasting, weight loss, vitamin deficiencies, and low protein levels.