Imagine that a patient who arrives in the perioperative area with no significant medical history is scheduled for a routine outpatient procedure. The patient later leaves the OR suite not for home, but instead to spend a day or more recovering in the ICU. For reasons unknown, the patient is lethargic, difficult to arouse, and suffering from shallow breathing with low tidal volumes. After costly medical testing and an extended stay, the patient is suspected of having carnitine deficiency and is referred to the medical genetics department for genetic testing.
What's a carnitine deficiency?
Carnitine is an amino acid acquired primarily through dietary intake of meat and dairy products.1 Carnitine is utilized by the cells to process long-chain fatty acids and produce energy.1,2 Patients with carnitine deficiency have defective proteins called carnitine transporters that bring carnitine into cells.2 This deficiency, also known as carnitine uptake deficiency, can impair energy production and cause an accumulation of metabolites.3
Carnitine deficiency is autosomal recessive, which means that both parents have to carry a copy of a mutated, unexpressed gene (SLC22A5) and pass it along to their child. In the few studies that have been completed, the mutation was estimated to occur in 1 in 40,000 births.2 Carnitine deficiency occurs equally in both sexes and all ethnic backgrounds.
Using genomic information
Using genomic information to provide individualized care can make the healthcare experience safer. To gather this data, nurses need to routinely assess patients for a history of unusual reactions that they or their biological family members have had to anesthesia and surgical procedures.
Fasting the usual number of hours prior to surgery can be dangerous for someone with carnitine deficiency. Patients with carnitine deficiency who begin fasting prior to midnight on the night before a surgery are at a greater risk for severe episodes of hypoglycemia.1 This condition results from the body's inadequate intake of, or inability to metabolize, the amino acid carnitine. It can cause a heterogeneous group of disorders, which include impaired muscle metabolism, myopathy, cardiomyopathy, hypoglycemia, and hypoketotic encephalopathy.4
Signs and symptoms
Clinical signs and symptoms vary and will depend on the heterogeneous disorder that the patient develops. Possible signs and symptoms include: decreased appetite, nausea and vomiting, irritability, hepatomegaly, diarrhea, hypochromic anemia, recurrent infections, exercise intolerance, and seizures. Lab findings may indicate anemia, metabolic acidosis, and hypoglycemia.3
Infants typically present with hypoglycemia, while older individuals present with skeletal or heart myopathies.1
Treatment options
Patients with carnitine deficiency have an excellent prognosis with treatment and continued supplementation. This disease can be treated by giving levocarnitine orally, or in acute situations, by using 10% dextrose in water and administering a weight-based I.V. infusion for patients who are N.P.O. Some patients may require supplementation with medium chain triglycerides and essential fatty acids.
For patients unwilling to medically treat their carnitine deficiency, subsequent surgical preparation and procedures can be adjusted to maintain safety. Some safety methods may include reducing fasting times for patients with known carnitine deficiency, supplementing diets with medium chain triglycerides and essential fatty acids, and monitoring blood glucose closely.4
Siblings of affected persons may want to have genetic carnitine deficiency testing prior to a surgical procedure to determine whether they also have the disorder and require specialized care. It may also be possible to determine if a patient has carnitine deficiency using mass spectrometry to screen blood, or by determining acylcarnitine levels in serum, urine, and tissues.4
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