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Fasting hypoglycaemia secondary to carnitine deficiency: a late consequence of gastric bypass
  1. Xin Chen,
  2. Brad Kimura,
  3. Jodi Nagelberg and
  4. Karen C McCowen
  1. University of California San Diego, La Jolla, California, USA
  1. Correspondence to Dr Karen C McCowen; kmccowen{at}


Twelve years following gastric bypass surgery, a cachectic 69-year-old woman presented with both fasting and postprandial hypoglycaemia. Postprandial symptoms were relieved by dietary modification and acarbose, as is common in such cases. During a supervised fast, symptomatic hypoglycaemia occurred. Concurrent laboratory testing showed suppression of plasma insulin, c-peptide, proinsulin and insulin-like growth factor II. However, beta-hydroxybutyrate was also low, surprising given insulin deficiency. Elevated plasma free fatty acid (FFA) concentrations suggested that lipolysis was not impaired, making cachexia/malnutrition a less likely cause of hypoglycaemia. The apparent diagnosis was failure to counter-regulate—subsequent plasma carnitine measurements showed carnitine deficiency which presumably prevented FFA transport across mitochondrial membranes for ketogenesis. Repletion with high-dose oral carnitine supplements effected resolution of fasting hypoglycaemia.

  • metabolic disorders
  • malabsorption
  • malnutrition
  • vitamins and supplements
  • gastrointestinal surgery

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  • Contributors There are three endocrinology trainees (XC, BK and JN) and one consultant endocrinologist (KCM) as authors. We all four wrote the manuscript together. BK and KCM met the patient during her second hospitalisation and worked her up. JN took over inpatient management and got the carnitine started. XC met the patient during a subsequent hospitalisation and together with KCM, has been regularly seeing the patient as an outpatient to help supervise her glucose levels and carnitine and overall care.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.