A 78-year-old woman is brought to the physician by her daughter due to intermittent dizziness, weakness, and confusion. The patient was seen for fever and dysuria 3 days ago and started on trimethoprim/sulfamethoxazole. Her other medical problems include type 2 diabetes mellitus, hypertension, and chronic kidney disease with a baseline serum creatinine of 1.3 mg/dL. Her chronic medications include hydrochlorothiazide, amlodipine, glyburide, atorvastatin, calcium, vitamin D, and alendronate.
Her temperature is 36.8 C (98.2 F) , blood pressure is 140/85 mm Hg supine and 144/89 mm Hg standing, pulse is 84/min, and respirations are 20/min. BMI is 19 kg/m². There are no focal neurologic findings. Her Mini-Mental State Examination score is 24/30.
Laboratory results are as follows:

Which of the following is the best next step in management of this patient?

Question

A 78-year-old woman is brought to the physician by her daughter due to intermittent dizziness, weakness, and confusion. The patient was seen for fever and dysuria 3 days ago and started on trimethoprim/sulfamethoxazole. Her other medical problems include type 2 diabetes mellitus, hypertension, and chronic kidney disease with a baseline serum creatinine of 1.3 mg/dL. Her chronic medications include hydrochlorothiazide, amlodipine, glyburide, atorvastatin, calcium, vitamin D, and alendronate.
Her temperature is 36.8 C (98.2 F) , blood pressure is 140/85 mm Hg supine and 144/89 mm Hg standing, pulse is 84/min, and respirations are 20/min. BMI is 19 kg/m². There are no focal neurologic findings. Her Mini-Mental State Examination score is 24/30.
Laboratory results are as follows:

Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This elderly woman has features suggesting symptomatic hypoglycemic episodes that are likely due to a drug interaction between trimethoprim/sulfamethoxazole (TMP-SMX) and glyburide in the setting of chronic kidney disease (CKD). Glyburide is a long-acting sulfonylurea medication that can accumulate in patients with CKD and carries a significant risk of hypoglycemia in elderly patients. TMP-SMX can potentiate the effect of sulfonylureas and cause unexpected hypoglycemia in previously stable patients. This patient's hemoglobin A_1C (HbA_1C) indicates well-controlled blood glucose over the past 3 months, and she is likely lacking adequate carbohydrate intake. In addition, her CKD decreases gluconeogenesis and glycogenolysis and impairs her defenses against hypoglycemia. The most appropriate action would be to discontinue glyburide and readjust her glycemic control to target a higher HbA_1C. Many experts recommend an HbA_1C of 7.0%-7.9% in elderly patients with longstanding diabetes and an anticipated life expectancy of <10 years. _1C _1C _1C _1C (Choice B) Diuretic use in elderly patients can cause orthostatic hypotension, dizziness, and falls. However, this patient has no signs of hypovolemia or orthostasis. Loop diuretics are preferred over thiazides for patients with hypertension and advanced CKD (glomerular filtration rate <30 mL/min/1.73 m²). However, this patient has good blood pressure control and her antihypertensive regimen need not be changed at this time. ² (Choice C) In the absence of focal neurologic findings, brain imaging studies (CT or MRI) are not recommended at this visit but may be indicated if her symptoms continue. (Choice D) Renal ultrasound can detect obstructive uropathy (from kidney stones) or perinephric abscess, which can present with persistent costovertebral angle pain and pyuria after urinary tract infections or pyelonephritis. However, this patient's stable vital signs and normal white blood cell count make these less likely. (Choice E) Absence of fever and resolution of dysuria make persistent urinary tract infection unlikely in this patient. Her minimal pyuria and bacteruria on urinalysis may indicate asymptomatic bacteruria, which does not require further evaluation. Educational objective: Sulfonylureas (eg, glyburide) can accumulate in elderly patients with chronic kidney disease (CKD) and cause hypoglycemia; this effect is potentiated by trimethoprim/sulfamethoxazole. Goals for diabetes control should be relaxed in elderly individuals with CKD. __________ References: Emergency hospitalization for adverse drug events in older Americans. (http://www.ncbi.nlm.nih.gov/pubmed/22111719) Coadministration of co-trimoxazole with sulfonylureas: hypoglycemia events and pattern of use. (http://www.ncbi.nlm.nih.gov/pubmed/24858839)

A 78-Year-Old Woman Is Brought to the Physician by Her