Nutritional Assessment

NUTRITION CARE PROCESS: OVERVIEW The nutrition care process (NCP) is defined as: “The systematic approach used by the registered dietitian (RD) to identify, diagnose, and treat any nutrition-related problems or disorders”. There are four components to the NCP: Nutrition assessment; Nutrition diagnosis; Nutrition intervention, and Nutrition monitoring and evaluation We will focus specifically on nutrition assessment.

NUTRITION CARE PROCESS: OVERVIEW Nutrition assessment is defined as: “A systematic process of obtaining, verifying, and interpreting data in order to make decisions about the nature and cause of nutrition-related problems.”

NUTRITION CARE PROCESS: OVERVIEW Nutrition assessment includes the “A–Es of assessment. A — anthropometric or body composition measurements B — biochemical analyses, the prime focus of this chapter C — clinical examination usually performed by the physician or other health care provider D — dietary analysis and assessment to determine usual food intake generally performed by the registered dietitian E — environmental assessment, which includes a consideration of all the other aspects of the individual’s environment that may affect his/her ability to purchase, prepare, and consume food. prefix 'anthropo' refers to 'human' and 'metric' refers to 'measurement. Weight, Height, head circumference, fat D—dietary analysis: An estimation of the total daily calorie intake,

BIOCHEMICAL ASSESSMENT/ MARKERS Biochemical assessment/markers are divided into: macronutrients and micronutrients. The macronutrients include markers of: carbohydrate, protein, and fat metabolism and utilization. How these markers change during inflammation and disease can be important to know if treatment is to be effective. Health care providers appreciate the clinical laboratory assessment of these markers and expect to receive the results in a timely manner

BIOCHEMICAL ASSESSMENT/MARKERS Micronutrients measurements are often the more difficult to obtain. Insufficient or excessive vitamins and/or excess or deficient minerals can have a serious impact on the enzymes and biochemistry of the human body. In particular, trace elements or minerals are especially important to many biologically significant metabolic reactions.

BIOCHEMICAL ASSESSMENT/MARKERS There is a close interrelationship between the function of certain organs in the body and nutrient balance/ imbalance, both positive and negative. Liver function will be affected if there is insufficient protein and excess fats. An excessive intake of protein may also be harmful to kidney function. Other nutrient imbalances can affect the heart (fats, water imbalances, vitamin deficiencies or excesses, selenium, etc.) The thyroid in particular requires adequate tyrosine levels for hormone synthesis but also requires adequate iron levels as enzyme cofactors for the formation and degradation of T4 and T3.

BIOCHEMICAL ASSESSMENT/MARKERS Macronutrients- Proteins Protein Markers in Nutritional Assessment The primary objective of nutritional assessment is to identify the patient who is malnourished and then to preserve or replenish the protein component of the body, through nutritional therapy Laboratory nutritional assessment is best accomplished by monitoring selected serum proteins. The ideal proteins have a short biologic half-life and reflect changes in protein status by measuring concentration changes in the serum.

BIOCHEMICAL ASSESSMENT/MARKERS Macronutrients- Proteins The concentration of protein markers of malnutrition are affected by protein malnutrition associated with end-stage liver and renal disease and severe infection and, most significantly, by stress injury

BIOCHEMICAL ASSESSMENT/MARKERS Macronutrients- Proteins Albumin Albumin has long been used in the assessment of hospitalized patients. The albumin concentration in the body is influenced by albumin synthesis, degradation, and distribution. The long biologic half-life of albumin (~20 days) allows changes in the serum concentration only after long periods of malnutrition. Serum albumin is not a good indicator of short-term protein and energy deprivation; however, albumin levels are good indicators of chronic deficiency.

BIOCHEMICAL ASSESSMENT/MARKERS Macronutrients- Proteins Albumin has been used to help determine two important nutritional states: Kwashiorkor: Chronic protein deficiency under conditions of adequate non–-protein-calorie intake Marasmus: caloric insufficiency without protein insufficiency Studies have classified various levels of malnutrition by using albumin levels in serum: ≥35 g/L are considered normal 28–30 to 35 g/L indicate mild malnutrition, 23–25 to 28–30 g/L indicate moderate malnutrition, >23–25 g/L indicate severely depleted levels of albumin

BIOCHEMICAL ASSESSMENT/MARKERS Macronutrients- Proteins Transthyretin Also called thyroxine-binding prealbumin or prealbumin Transthyretin and Retinol Binding Protein (RBP) are considered the major transport proteins for thyroxine and vitamin A, respectively Because of its short half-life (48h) and small body pool, transthyretin is a better indicator of positive nitrogen balance than albumin Conc. increases in patients with positive nitrogen balance and decreases in patients with negative nitrogen balance. Transthyretin is a superior indicator for monitoring short- term effects of nutritional therapy Nitrogen Balance = Nitrogen intake - Nitrogen loss

BIOCHEMICAL ASSESSMENT/MARKERS Macronutrients- Proteins Insulin Growth Factor I Insulin growth factor-1 (IGF-1) is important for stimulation of growth. IGF-1 serum concentrations are regulated by growth hormone and nutritional intake. Growth hormone stimulates the liver to produce IGF-1, which circulates bound to IGF-BP3. IGF-1 has been used as a nutritional marker in adults and children.

BIOCHEMICAL ASSESSMENT/MARKERS Macronutrients- Proteins Nitrogen Balance Another nutritional evaluation tool, nitrogen balance, Nitrogen Balance = Nitrogen intake - Nitrogen loss It is one of the most widely used indicators of protein change and/or adequacy of feeding. In the healthy adult population, anabolic and catabolic rates are in equilibrium, and the nitrogen balance approaches zero In humans, 90%–95% of the daily nitrogen loss is accounted for by elimination through the kidneys. About 90% of this loss is in the form of urea.

BIOCHEMICAL ASSESSMENT/MARKERS Macronutrients- Proteins Therefore, the determination of 24-hour urinary urea nitrogen (UUN) is a method for estimating the amount of nitrogen excretion. The nitrogen balance is calculated as follows: Protein intake (in grams) is converted into grams of nitrogen by dividing by 6.25 ( (1 g N = 6.25g protein) The factor of 4 in the equation represents an estimation of nonurinary losses of nitrogen (e.g., from skin, feces, hair, and nails).

BIOCHEMICAL ASSESSMENT/MARKERS Micronutrients- Vitamins Vitamins have a wide range of functions in biologic tissue, serving as cofactors in many enzymatic reactions, so that these enzymes have low catalytic activity in cellular reactions if vitamins are not present. These compounds and their biologically inactive precursors must be partially obtained from food sources and, in some instances, from bacterial synthesis. When vitamin cellular and activity levels from diet or intestinal absorption are inadequate, it is termed vitamin deficiency. A nonprotein component of enzymes is called the cofactor. 

BIOCHEMICAL ASSESSMENT/MARKERS Micronutrients- Vitamins The term vitamin has an historical basis in deficiency states that were relieved by specific food intake. The most notable examples are: Scurvy (vitamin C, lime consumption); Rickets (vitamin D); Beriberi (thiamine); Night blindness, vitamin A Megaloblastic anemia, (folic acid); A combination of dietary history, physical examination, and laboratory measurements is often required to diagnose vitamin deficiency. a disease causing inflammation of the nerves and heart failure, caused by a deficiency of vitamin B1. Spina bifida is a birth defect where there is incomplete closing of the backbone and membranes around the spinal cord

BIOCHEMICAL ASSESSMENT/MARKERS Micronutrients- Vitamins Chemical determination of human vitamin states has been approached in the following ways: Measurement of active cofactors or precursors in biologic fluids or blood cells Measurement of urinary metabolites of the vitamin Measurement of a biochemical function requiring the vitamin (e.g., enzymatic activity), with and without in vitro addition of the cofactor form Measurement of urinary excretion of vitamin or metabolites after a test load of the vitamin Measurement of urinary metabolites of a substance, the metabolism of which requires the vitamin after administration of a test load of the substance

BIOCHEMICAL ASSESSMENT/MARKERS Micronutrients- Vitamins Reduced serum concentrations of a vitamin do not always indicate a deficiency that interrupts cellular function. Conversely, values within the reference interval do not always reflect adequate function. Interpretation of laboratory values must be done with knowledge of the biochemistry and physiology of vitamins.

BIOCHEMICAL ASSESSMENT/MARKERS Micronutrients- Vitamins Fat-Soluble Vitamins- Vitamin A Major dietary sources includes animal products and pigmented fruits and vegetables (carotenoids). Vitamin A is stored in the liver and transported in the circulation complexed to RBP and transthyretin. Vitamin A deficiency is most common among children living in nonindustrialized countries and is usually a result of insufficient dietary intake. Deficiency may also occur because of chronic fat malabsorption or impaired liver function or may be associated with severe stress and protein malnutrition.

BIOCHEMICAL ASSESSMENT/MARKERS Micronutrients- Vitamins Premature infants are born with lower serum retinol and RBP levels When ingested in high doses, either chronically or acutely, vitamin A causes many toxic manifestations and may ultimately lead to liver damage due to hypervitaminosis. Measurement of retinol is the most common means of assessing vitamin A status in the clinical setting. Retinol is most commonly measured by high-performance liquid chromatography (HPLC). Toxicity is usually assessed by measuring retinyl ester levels in serum rather than retinol, which is accomplished by HPLC. Vitamin A is found in the form of retinol and only a small proportion is retinyl esters In Vit. A intoxication, retinyl ester to retinol exceeds 10%