An asymptomatic 72-year-old man presents to his primary care physician for a scheduled health maintenance visit. His past medical history is significant for polycythemia vera and essential hypertension. His daily medication regimen consists of low-dose aspirin and amlodipine. The patient states he feels completely well and denies any recent muscle weakness, palpitations, syncope, or shortness of breath.
Vital signs show a temperature of 37.0°C (98.6°F), blood pressure of 135/82 mmHg, pulse of 78/min, and respiratory rate of 14/min. Physical examination reveals a plethoric appearance of the face and mild splenomegaly. A 12-lead electrocardiogram demonstrates normal sinus rhythm with normal QRS duration and no ST-segment or T-wave abnormalities.
Laboratory results obtained from a serum sample are as follows:
| Test | Result | Reference Range |
|---|---|---|
| Sodium | 140 mEq/L | 136–145 mEq/L |
| Potassium | 6.7 mEq/L | 3.5–5.0 mEq/L |
| Chloride | 104 mEq/L | 98–106 mEq/L |
| Bicarbonate | 25 mEq/L | 22–28 mEq/L |
| Blood urea nitrogen | 16 mg/dL | 8–20 mg/dL |
| Creatinine | 1.0 mg/dL | 0.6–1.2 mg/dL |
| Hemoglobin | 17.5 g/dL | 13.5–17.5 g/dL |
| Leukocytes | 14,000/mm³ | 4,500–11,000/mm³ |
| Platelets | 1,250,000/mm³ | 150,000–400,000/mm³ |
Which of the following is the most likely mechanism responsible for the abnormal potassium level reported in this patient?
- Release of intracellular potassium during in vitro blood clottingCevap
- BShift of potassium from the intracellular to the extracellular space
- CIn vivo destruction of erythrocytes due to microvascular shear stress
- DMedication-induced impairment of the renin-angiotensin-aldosterone system
- EDecreased renal tubular secretion due to occult nephropathy