A 75-year-old man is brought to the emergency department due to a 2-day history of progressive lethargy and confusion. His family reports that he has had fatigue and blurred vision over the last several days. The patient was recently diagnosed with polymyalgia rheumatica and is taking prednisone. Medical history is notable for diet-controlled type 2 diabetes mellitus, hypertension, and hyperlipidemia. Temperature is 37.9 C (100.2 F), blood pressure is 90/60 mm Hg, pulse is 112/min, and respirations are 18/min. Oral mucous membranes are dry. The lungs are clear to auscultation, and the heart has a regular tachycardia with no murmur. The neck is supple. The patient is somnolent but arousable and moves all extremities equally on command. Laboratory results are as follows: Urinalysis shows trace ketones. Which of the following is the most likely cause of this patient's altered sensorium?

Question

A 75-year-old man is brought to the emergency department due to a 2-day history of progressive lethargy and confusion.  His family reports that he has had fatigue and blurred vision over the last several days.  The patient was recently diagnosed with polymyalgia rheumatica and is taking prednisone.  Medical history is notable for diet-controlled type 2 diabetes mellitus, hypertension, and hyperlipidemia.  Temperature is 37.9 C (100.2 F), blood pressure is 90/60 mm Hg, pulse is 112/min, and respirations are 18/min.  Oral mucous membranes are dry.  The lungs are clear to auscultation, and the heart has a regular tachycardia with no murmur.  The neck is supple.  The patient is somnolent but arousable and moves all extremities equally on command.  Laboratory results are as follows:  Urinalysis shows trace ketones.  Which of the following is the most likely cause of this patient's altered sensorium?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d3b5_3e0d_bc81_5751bc96d44f_MD0003_00 This patient with type 2 diabetes mellitus has hyperosmolar hyperglycemic state (HHS), characterized by high plasma osmolality and severe hyperglycemia (often >1,000 mg/dL) due to relative insulin deficiency and/or elevated counterregulatory hormones (eg, cortisol). Common precipitating factors include: Infection Medications impacting carbohydrate metabolism (eg, glucocorticoids, thiazide diuretics, atypical antipsychotics) Interruption of insulin therapy Trauma or acute illness (eg, myocardial infarction) Severe hyperglycemia causes glycosuria, osmotic diuresis, hypovolemia, and dehydration. With worsening hypovolemia, glomerular filtration rate (GFR) declines, leading to reduced renal glucose excretion and worsening hyperglycemia. Elderly individuals are at increased risk due to altered perception of thirst and restricted fluid intake. Neurologic symptoms ranging from confusion to coma are due primarily to high plasma osmolality, usually >320 mOsm/kg; this patient's calculated osmolality is approximately 336 mOsm/kg (using the reported sodium level, not that corrected for hyperglycemia). In contrast to diabetic ketoacidosis (DKA), which typically develops rapidly over hours, HHS develops over a few days to weeks. calculated osmolality (Choice A) Glucocorticoid-induced psychosis is characterized by delusions, hallucinations, disorganized thought processes, and aggression. Lethargy is less typical. (Choice C) Mental status changes in hyponatremia are due to cerebral edema (water flowing from the hypoosmolar extracellular space into brain cells). In HHS, plasma osmolality is elevated due to excess glucose, drawing water out of cells, which lowers plasma sodium (dilution hyponatremia); however, cerebral edema does not occur. The effective sodium concentration can be corrected for hyperglycemia; this patient's corrected sodium is approximately 152. corrected for hyperglycemia (Choices D and E) Anion gap is also calculated using reported, not corrected, serum sodium. This patient's normal anion gap and serum bicarbonate make metabolic acidosis, including DKA, unlikely. In HHS, mild ketosis (ie, urine ketones) may occur due to decreased food intake (ie, starvation ketosis); however, unlike DKA, more prominent ketosis does not occur because even relatively low insulin production suppresses ketogenesis. Anion gap (Choice F) In kidney injury, uremic toxin buildup can cause mild symptoms (eg, fatigue, nausea) when the GFR falls below 60 mL/min/1.73 m². However, more severe symptoms, as seen in this patient, would typically be observed only at an estimated GFR <10-20 mL/min/1.73 m². ² ² Educational objective: Hyperosmolar hyperglycemic state in type 2 diabetes mellitus is characterized by severe hyperglycemia and hyperosmolality without significant ketoacidosis. Altered sensorium is due to high plasma osmolality. Common precipitating factors include infection, medications (eg, glucocorticoids), interruption of insulin therapy, trauma, and acute illness. References: Hyperosmolar hyperglycemic state: a historic review of the clinical presentation, diagnosis, and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/25342831)

A 75-Year-Old Man Is Brought to the Emergency Department Due