From the Guidelines
Laboratory tests used to monitor nutritional status include serum albumin, prealbumin, transferrin, and total protein to assess protein status; complete blood count to detect anemia related to iron, folate, or vitamin B12 deficiencies; serum electrolytes including sodium, potassium, calcium, magnesium, and phosphorus; lipid panels to evaluate cholesterol and triglycerides; and specific vitamin levels such as vitamins A, D, E, K, B12, and folate. These tests provide objective data about a patient's nutritional health, allowing for targeted interventions. The choice of tests depends on the clinical situation, with albumin and prealbumin being common initial screenings due to their sensitivity to protein status, though albumin has limitations as an acute-phase reactant affected by inflammation 1. Regular monitoring of these parameters is essential for patients with malnutrition, chronic diseases, post-surgery, or those receiving specialized nutrition support. Additional tests include iron studies (ferritin, total iron binding capacity), zinc, copper, and selenium levels for micronutrient assessment 1. Nitrogen balance studies and 24-hour urinary creatinine can evaluate muscle mass, while blood glucose, hemoglobin A1c, and insulin levels help assess carbohydrate metabolism. For patients with specific conditions, such as cystic fibrosis, annual assessment of pancreatic function by fecal pancreatic elastase-1 determination and monitoring of growth, nutritional status, and gastrointestinal symptoms are recommended 1. In patients with chronic renal failure, serial measurements of serum albumin, edema-free actual body weight, and normalized protein nitrogen appearance (nPNA) or dietary interviews and diaries are recommended 1. Overall, the selection of laboratory tests to monitor nutritional status should be individualized based on the patient's clinical condition and nutritional needs.
From the Research
Laboratory Tests for Nutritional Status
To monitor nutritional status, several laboratory tests can be used, including:
- Serum albumin levels 2, 3, 4, 5
- Serum prealbumin levels 2, 3, 5
- Serum transferrin levels 2, 3
- Plasma vitamin A and retinol-binding protein concentrations 5
- Total protein concentration 4, 5
- Nitrogen balance 4
Protein Markers
Protein markers such as serum albumin, prealbumin, and transferrin can be used to assess nutritional status 6, 2, 3. These markers have different half-lives, with serum albumin having a longer half-life of approximately 20 days, making it a late index of nutritional status 2.
Anthropometric Variables
In addition to laboratory tests, anthropometric variables such as relative weight, triceps skinfold thickness, and arm muscle circumference can also be used to assess nutritional status 3.
Monitoring Nutritional Intervention
These laboratory tests and anthropometric variables can be used to monitor the effectiveness of nutritional interventions and identify patients who are at risk of malnutrition 6, 2, 3, 4.