A woman presented to the emergency department with abdominal pain, nausea, and vomiting.
Student Discussion Document (pdf)
Ayesha Farooq, Angela Treml, and Jessica M. Colón-Franco*†
Department of Pathology, Medical College of Wisconsin, Milwaukee, WI.
*Address correspondence to this author at: Laboratory Medicine, Cleveland Clinic, 10300 Carnegie Ave., Cleveland, OH 44106. Fax 216-445-0212; e-mail [email protected]
†Current affiliation: Pathology & Laboratory Medicine Institute, Cleveland Clinic, Cleveland Ohio.
woman presented to the emergency department with abdominal pain, nausea, and vomiting. On examination, she had abdominal tenderness and a medical history of diabetes mellitus type 1, hypertension, end-stage renal disease, liver disease (hepatic steatosis), hypothyroidism, chronic obstructive pulmonary disease, and congestive heart failure. The patient denied alcohol use or abuse.
Lipase was 680 U/L (reference interval, 13–60 U/L) and triglycerides were >4425 mg/dL [reference interval, <150 mg/dL (50 mmol/L)]. These results, along with clinical and radiologic findings, suggested a diagnosis of hypertriglyceridemia-mediated pancreatitis.
The patient was treated with insulin and heparin, but triglycerides remained >4425 mg/dL. Consequently, plasmapheresis was used to reduce the serum triglyceride concentrations on day 3 posthospital presentation, but triglycerides persisted at >4425 mg/dL (Table 1). The transfusion medicine team noticed the appearance of clear plasma during the next plasmapheresis course and called the laboratory to investigate.
Triglyceride testing in a reference laboratory followed (Table 1). The CDC method also revealed markedly increased triglycerides at 6620 mg/dL (74.8 mmol/L). However, triglycerides were 151 mg/dL (1.7 mmol/L) in a glycerol-corrected triglyceride assay (Roche Triglyceride/Glycerol Blanked Reagent, Roche Diagnostics). Glycerol concentrations were calculated (triglycerides, CDC - triglycerides, glycerol corrected) to be 6469 mg/dL (73.1 mmol/L) [reference interval, 3.5–32.7 mg/dL (0.04 – 0.37 mmol/L)]. In other words, 6469 mg/dL (73.1 mmol/L) of the 6620 mg/dL (74.8 mmol/L) in this sample represented free glycerol and not triglyceride-derived glycerol.
Questions to Consider
- What is measured in blanked and nonblanked triglyceride tests?
- What conditions could lead to these findings?
- How can the laboratory identify falsely increased triglycerides?
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