Rapamycin is an mTOR inhibitor that has been shown to extend the lifespan of laboratory model organisms. In humans, rapamycin is used at higher doses as an immunosuppressive medication to prevent organ rejection. Numerous adverse effects are seen with rapamycin treatment in humans, with one of the most common being dysregulation of lipid metabolism. In humans, this often manifests as mild to moderate serum lipid elevations, with a small subset developing extreme triglyceride elevations. This case report describes an eight-year-old, castrated male, clinically healthy Labrador retriever who developed severe hypertriglyceridemia associated with low-dose rapamycin administration over a six-month period. During this time, the dog was asymptomatic and displayed no other clinical abnormalities, aside from a progressive lipemia. Within 15 days of discontinuing rapamycin treatment, and with no targeted lipemic intervention, the dog\'s lipemia and hypertriglyceridemia completely resolved.

Hypertriglyceridemia is the third most common cause of acute pancreatitis after gallstones and long-term alcohol use. There are specific therapeutic options unique to hyperglyceridemia-induced pancreatitis, such as continuous insulin therapy and plasmapheresis, emphasizing the importance of identifying hypertriglyceridemia as the cause. Triglyceride levels > 1000 mg/dL may result in a visibly lipemic blood sample. Lipemic samples may interfere with laboratory equipment, resulting in erroneous levels or the inability to measure several serum blood tests. Consider hypertriglyceridemia as a cause for acute pancreatitis in the setting of a lipemic blood sample or when gallstones have been excluded.

The deleterious effects of high serum lipid content on the membrane lung (ML) during extracorporeal membrane oxygenation (ECMO) are sparsely documented, and the threshold of lipemia-induced membrane failure is poorly described. We present a case of a patient on venovenous ECMO who developed ML failure after 7 days due to moderate to severe hypertriglyceridemia (700-800 mg/dL). ML failure was exhibited by impaired gas exchange and high transmembrane pressures, and there was notable lipemic layering in the circuit immediately after decannulation. This case demonstrates that in addition to patients with extreme lipemia, ML failure can also occur in patients with moderate to severe hypertriglyceridemia. Hypertriglyceridemia should be suspected in patients with high transmembrane pressures and ML failure not attributable to thrombosis, and these patients may require frequent ML changes if a prolonged ECMO run is required.

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.1.

Lipemia can influence laboratory test results by different mechanisms. Although the liquid chromatography-tandem mass spectrometry (LC-MS/MS) is considered the reference method for 25(OH)D3, some compounds (carbohydrate, lipids, proteins, etc.) in the blood may cause a false result indicating a negative or positive deviation rate from the correct blood level of the test.
In this paper, we report a case of D vitamin intoxication due to a false negative result caused by lipemia. A young woman with a complaint of pain in multiple joints applied to the physical therapy clinic and was found to have some cystic bone lesions. She was eventually diagnosed with DM tip 1, familial hyperlipidemia, and nephrolithiasis. Although she had D vitamin replacement therapy, low levels of blood 25(OH)D3 concentration, measured by an LC-MS/MS device, were detected. After blood dilution, a high level of 25(OH)D3 and blood intoxication due to lipid interference were indicated.
From this case, we can conclude that analytical errors caused by the ingredients of a blood sample may lead to unnecessary treatment and intoxication. While evaluating the blood 25(OH)D3 levels, clinicians should guard against false-negative results due to interference in patients with familial hyperlipidemia.