Review Question - QID 104517

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Endocrine Medications QID: 104517 (M2.PH.14.70)

QID 104517 (Type "104517" in App Search)

A 66-year-old man presents to the emergency department with abdominal pain, nausea, and vomiting. He endorses diffuse abdominal tenderness. His past medical history is notable for diabetic nephropathy, hypertension, dyslipidemia, depression, and morbid obesity. He also is currently being treated for an outbreak of genital herpes. His temperature is 99.0°F (37.2°C), blood pressure is 184/102 mmHg, pulse is 89/min, respirations are 18/min, and oxygen saturation is 98% on room air. Physical exam is notable for an obese man in no acute distress. A CT scan of the abdomen with contrast is performed and is unremarkable. The patient is admitted to the observation unit for monitoring of his pain. Notably, the patient's abdominal pain improves after an enema and multiple bowel movements. The patient's evening laboratory values are ordered and return as seen below.

Serum:
Na+: 141 mEq/L
Cl-: 99 mEq/L
K+: 4.8 mEq/L
HCO3-: 11 mEq/L
BUN: 65 mg/dL
Glucose: 177 mg/dL
Creatinine: 3.1 mg/dL (baseline: 2.8 mg/dL)

Which of the following is the most likely etiology of this patient's laboratory derangements?

Type & Select Correct Answer

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Acyclovir

23%

8/35

Atorvastatin

51%

18/35

Insulin

2/35

Metformin

11%

4/35

Metoprolol

2/35

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This patient has poor kidney function likely exacerbated by dehydration from a viral gastroenteritis (thus his creatinine of 3.1 mg/dL and a history of diabetic nephropathy) as well as a lactic acidosis after receiving a contrast load (CT scan with contrast). A lactic acidosis is a possible complication in patients with poor kidney function who take metformin.

Metformin is an oral hypoglycemic agent that works by decreasing gluconeogenesis in the liver. It is widely regarded as the first-line oral diabetic agent. Its most concerning side effect is the development of a lactic acidosis in patients with poor renal function. Generally, patients tolerate this medication well. However, patients with poor kidney function (such as those with severe/poorly treated hypertension, diabetic nephropathy, or someone with poor kidney function who is given a contrast load) can suffer this feared complication. Whenever a patient has worsening kidney function they should no longer take metformin given this possible complication. Management of the lactic acidosis includes stopping metformin, IV fluids, and close monitoring.

Incorrect Answers:
Answer 1: Acyclovir can cause a crystalline nephropathy in the setting of poor kidney function but is not commonly associated with a lactic acidosis. This complication can be prevented by keeping the patient well hydrated.

Answer 2: Atorvastatin can cause rhabdomyolysis which presents with muscle pain, hyperkalemia, hypocalcemia, and myoglobinuria. For this reason, statins are often given at night.

Answer 3: Insulin is a safe alternative to metformin in patients with poor kidney function. Insulin overdose can cause hypoglycemia which can be treated with dextrose administration.

Answer 5: Metoprolol toxicity presents with somnolence, bradycardia, hypotension, and hypoglycemia and is treated with glucagon, insulin, dextrose, calcium, epinephrine, and lipid emulsion therapy.

Bullet Summary:
Metformin can cause a lactic acidosis in the setting of poor kidney function.

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