Total Parenteral Nutrition, or TPN is an intravenous nutrition support therapy. It is used to prevent malnutrition if you cannot use your gastrointestinal tract for the digestion, absorption and metabolism of nutrients. It contains amino acids, dextrose, lipids, vitamins and minerals. Dextrose is the carbohydrate source, and when it is continuously infused into the bloodstream blood glucose levels can rise, resulting in hyperglycemia.
Blood Glucose Ranges
Normal ranges for blood glucose are between 70 to 100 milligrams per deciliter. People who have levels in the range of 100 to 125 milligrams per deciliter are at an increased risk of developing diabetes. Fasting blood glucose levels that are greater than 126 milligrams per deciliter confirm a diagnosis of diabetes. Hypoglycemia -- when your blood sugar is too low -- is defined as a level less than 70 milligrams per deciliter.
High blood glucose values are a common metabolic complication of TPN. The constant infusion of dextrose can increase blood glucose levels. In a 2010 study published in "Diabetes Care," researchers attempted to determine what impact hyperglycemia -- high blood sugar -- resulting from TPN infusion had on 276 hospitalized patients. They concluded that increased blood glucose resulted in longer hospital stays, more complications and an increased risk of mortality.
Critically Ill Patients
Patients that are critically ill have a high rate of hyperglycemia when receiving TPN. A landmark study published in the “New England Journal of Medicine” in 2001 concluded that maintaining blood glucose levels at 110 milligrams per deciliter reduces morbidity and mortality among critically ill patients in the surgical intensive care unit. A 2011 study published in “Nutrition Research and Practice” set out to determine if TPN provided to patients in the first week in the intensive care unit was related to the development of hyperglycemia. Researchers concluded that the amount of carbohydrate provided in TPN may impact blood glucose levels and should be limited.
Reasons for Elevations
Blood glucose levels can also be increased if too many calories are provided in the TPN from carbohydrates. The dextrose grams should be limited to 150 grams per day to start. If levels are not monitored to ensure acceptable ranges, then blood glucose values can worsen. Hyperglycemia can also be related to infections patients on TPN may acquire while in the hospital. Better patient outcomes are associated with improved blood glucose levels when patients are receiving TPN.
- Nutritional Issues in Gastroenterology: The Hitchhiker’s Guide to Parenteral Nutrition Management For Adults
- Diabetes Care: Diagnosis and Classification of Diabetes Mellitus
- Diabetes Care: Hyperglycemia is Associated With Adverse Outcomes In Patients Receiving Total Parenteral Nutrition.
- Diabetes Care: Hyperglycemia During Total Parenteral Nutrition
- New England Journal of Medicine: Intensive Insulin Therapy in Critically Ill Patients.
- Nutrition Research Practice: Higher Dextrose Delivery via TPN Related to the Development of Hyperglycemia In Non-Diabetic Critically Ill Patients.
- Gastroenterology Research and Practice: Hyperglycemia in Hospitalized Patients Receiving Parental Nutrition Is Associated with Increased Morbidity and Mortality: A Review
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