Abstract
We report a case of a 55-year-old woman with hypertension and diabetes mellitus, who took tamoxifen for the past 4 years. She presented with acute pancreatitis caused by markedly elevated serum triglycerides (3,883 mg/dL). Tamoxifen is known to cause a mild increase in serum triglycerides, but it rarely increases to such high levels to cause acute pancreatitis. The patient recovered well, and tamoxifen was switched to letrozole. It is crucial to monitor serum lipids up to 4 years and beyond for patients on tamoxifen, particularly in patients with known dyslipidemia or diabetes mellitus.