A Case Comparison of Postprandial Lipemia Using a Novel Tracer in People with and Without Varying Levels of Spinal Cord Injury

Research Objectives: To compare postprandial lipemia (PPL) in people without spinal cord injury (SCI) and cases with different neurological levels

Design: Case series

Setting: University laboratory at an academic medical center

Participants: Cases were selected because they had “excellent” normative upper extremity cardiorespiratory fitness relative to level of injury (1 non-injured, 1 paraplegic, 1 tetraplegic) and relatively well-matched diets. Inclusion criteria are a neurologically stable injury having occurred > 1 year from test date and ASIA A impairment. Exclusion criteria includes existing cardiovascular disease, diabetes, or pressure ulcer within the last 3 months.

Interventions: Participants consumed a population-specific test meal containing 20 kcal·kg -1 fat-free mass (FFM-1) with a ratio of 50:35:15 carbohydrates, lipids, and protein (Carb:Fat:Pro). The meal was enriched with 5 mg·kgFFM-1 of stable isotope lipid tracer ([U-13C]palmitate) to track endogenous and exogenous postprandial lipid metabolism. Blood samples, arterialized via the heated hand vein technique, were collected 1 hour prior to meal ingestion and serially for 400 minutes following.

Main Outcome Measures: Amplitude of circulating postprandial triglyceride

Results: Only the tetraplegic was lipemic at the final timepoint (2001 mM at 400 min post-meal). In this person, peak amplitude was also increased (3392 mM at X min), from both endogenous (3171 mM) and exogenous triglyceride (265 mM) sources. No other case exceeded the 2500 mM threshold for PPL. Despite increased amplitude and latency in tetraplegia, the relative pattern of endogenous and exogenous rise and fall was similar across all three cases.

Conclusions: In this case comparison designed to interrogate level of injury, we selected three cases with “excellent” lifestyle (fitness and diet) behaviors. Only the tetraplegic showed exaggerated PPL after ingestion of an SCI-specific meal challenge. While not sufficiently generalizable, this case comparison provides necessary evidence that, in chronic tetraplegia, it can be impossible to “out-lifestyle” neurogenic dyslipidemia.

Author(s) Disclosures: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.