Nutritional Assessment

DefinitionsEstimated Average Requirements(EAR) are

expected to satisfy the needs of 50% of the people in that age group based on a review of the scientific literature.

Recommended Daily Allowance(RDA) is the daily intake level of a nutrient which is considered sufficient by the food and Nutrition board to meet the requirements of 97.5% of healthy individuals in each life-stage and sex group . It is calculated based on EAR and is usually approximately 20% higher than EAR.

The RDA is used to determine the Recommended Daily Value(RDV) which is printed on food labeles in the U.S.A. and Canada.

Adequate Intake(AI) is used where no RDA has been established , but the amount established is somewhat less firmly believed to be adequate for everyone in the demographic group.

Nutrition Care Process (NCP):

Defined as “a systemic problem-solving method that dietetic professionals use to critically think and make decisions to address nutrition -related problems and provide safe and effective quality nutrition care.”

There are four components to the NCP:1. nutrition assessment.2. nutrition diagnosis.3. nutrition intervention.4. nutrition monitoring and evaluation.

Nutrition assessment includes:

A. Anthropometric or body composition measurements.

B. Biochemical analyses.

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 (RD).

E. Environmental assessment.

Nutrition assessmentA. Anthropometric measurements:

• Include the measurement of height and weight and, the calculation of the body mass index [BMI] .

• BMI: “used to assess overweight and obesity and to monitor changes in body weight.”

• Other measurements include a weight history, and possibly a waist circumference measurement.

Nutrition assessmentB. Biochemical assessment/markers:

• The macronutrients include markers of carbohydrate, protein, and fat metabolism and utilization.

• Micronutrients measurements include vitamins, minerals and trace elements are often the more difficult to obtain.

Nutrition assessmentC. The clinical component of the nutrition assessment:

• Consists of the history of present illness, the past medical history, and an inquiry into the family history.

• For example, the review of systems (ROS) is a head to-toe examination looking for signs of malnutrition and/or disease

• It includes a measurement of blood pressure as well as presence of any physical limitations/restrictions regarding physical movement/activity.

Nutrition assessment

D. The dietary component of the nutritional assessment:

• Determine the adequacy of the usual day’s intake with respect to nutritional recommendations that are specific for an individual’s age, gender, level of physical activity, and particular health conditions.

E. The environmental assessment:

• Takes into consideration all aspects of an individual’s environment or living conditions that may affect his or her ability to purchase, prepare, and/or consume food.

The information obtained from all A–E aspects of a complete nutrition assessment are then summarized and reviewed by the RD or other health care professional to determine:-

Nutrition diagnosis,

Nutrition intervention is designed and implemented,

Followed by monitoring and evaluation

BIOCHEMICAL MARKERSA. Macronutrients

1. Proteins:

Laboratory nutritional assessment is best accomplished by monitoring selected serum proteins.

The concentration of protein markers of malnutrition are affected by protein malnutrition associated with end-stage liver and renal disease and severe infection.

A separation of the inflammatory state from protein malnutrition can be problematic.

A.Macronutrients

A.Macronutrients2. Albumin Assessment of hospitalized patients. Influenced by albumin synthesis, degradation, and

distribution.• Low albumin levels have been identified as a predictor

of mortality in patients in long-term-care facilities.

• Albumin has been used to help determine two important nutritional states:

1. First; chronic protein deficiency under conditions of adequate non protein-calorie intake (hypoalbuminemia).

2. Second; albumin concentrations may help define marasmus “energy deficiency”. The serum albumin level remains normal but there is considerable loss of body weight.

A.Macronutrients

3. Transferrin

o Transferrin is a glycoprotein, synthesized in the liver and binds and transports ferric iron

o It is an early indicator of iron deficiency, and the elevated transferrin is the last analyte to return to normal when iron deficiency is corrected.

A.Macronutrients

4. Transthyretin In normal situations, each transthyretin subunit contains

one binding site for retinol-binding protein (RBP) "major transport proteins for thyroxine and vitamin A".

Transthyretin is a better indicator of visceral protein status and positive nitrogen balance than albumin and transferrin (because of its short half-life and small body pool).

The concentration of transthyretin and RBP complex, greatly decreased in protein-energy malnutrition.

A.Macronutrients5. Retinol-Binding Protein Used in monitoring short-

term changes in nutritional status.

Although RBP has a shorter half-life than transthyretin (12 hours, compared with 2 days), it is excreted in urine, and its concentration increases more significantly than transthyretin in patients with renal failure.

When decreases to levels of less than 80 mg/L, severe protein-calorie malnutrition develops; however, nutritional support can cause a daily increase of up to 10 mg/L.

A.Macronutrients

6. Insulin Growth Factor I Formerly termed somatomedin C, is

important for stimulation of growth.

Growth hormone stimulates the liver to produce IGF-1, which circulates bound to IGF-BP3.

IGF-I used as a nutritional marker in adults and children.

A.Macronutrients

7. Fibronectin

Is an a2-glycoprotein that serves important roles in cell-to-cell adherence and tissue differentiation, wound healing, microvascular integrity, and opsonization.

It is considered the major protein regulating phagocytosis.

Fibronectin concentrations may decrease after physiologic damage caused by severe shock, burns, or infection.

A.Macronutrients8. Nitrogen Balance

Nitrogen balance, is the difference between nitrogen intake and nitrogen excretion.

During stress, trauma, or burns, the nutritional intake decreases.

And due to an increase in catabolism, nitrogen losses increase and may exceed intake, leading to a negative nitrogen balance.

A.Macronutrients9. C-Reactive Protein

The flow phase of marked catabolism presents clinically with tachycardia, fever, increased respiratory rate, and increased cardiac output.

During this time, synthesis rates of C-reactive protein and other acute-phase proteins increase and albumin and pre-albumin decrease.

This produces weight loss with decreased albumin and prealbumin levels.

C-reactive protein is an acute-phase protein that increases dramatically under conditions of sepsis, inflammation, and infection.

A.Macronutrients10. Interleukins

Most nutritional investigations have been performed on interleukin-1 (IL-1), IL-6, and tumor necrosis factor- (TNF).

A.Macronutrients

o Parenteral nutrition therapy involves administering appropriate amounts of carbohydrate, amino acid, and lipid solutions, as well as electrolytes, vitamins, minerals, and trace elements, to meet the caloric, protein, and nutrient requirements while maintaining water and electrolyte balance.

11. Total Parenteral Nutrition (TPN)

o Because TPN administration bypasses normal absorption and circulation routes, careful laboratory monitoring of these patients is critical.

The Eat-Well Plate

B. Carbohydrates

1. Urine Testing• In small premature infants, glycosuria during the early phase

of TPN is a signal that glucose infusion is too rapid.

2. Tests to Monitor Electrolyte Disturbances

• Sodium regulation is a problem in children during TPN.

• Factors that increase the amount of sodium necessary to maintain normal serum sodium concentrations in both children and adults are glycosuria, diuretic use, diarrhea or other excessive gastrointestinal losses, and increased postoperative fluid losses.

C.MicronutrientsVitamins 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).• 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.

C.Micronutrients

Vitamins are classified into tow main categories:

1- Fat-soluble vitamins

2- Water-soluble vitamins.

Fat-Soluble Vitamins1. Vitamin A “Retinol”

• Retinol and retinoic acid are derived directly from dietary sources.

• Major dietary sources include animal products, pigmented fruits and vegetables (carotenoids).

• Vitamin A deficiency leads to night blindness.

• Epithelial cells become dry and keratinized.

• Excess vitamin A causes many toxic manifestations and may ultimately lead to liver damage.

• Commonly measured by high-performance liquid chromatography (HPLC).

2. Vitamin E “Tocopherol”

Fat-Soluble Vitamins

• Vitamin E is a powerful antioxidant and the primary defense against potentially harmful oxidations that cause disease and aging.

• The major role of vitamin E is protecting the erythrocyte membrane from oxidant stress.

• The major symptom of vitamin E deficiency is hemolytic anemia.

• Patients with conditions that result in fat malabsorption, especially cystic fibrosis and abetalipoproteinemia, are also susceptible to vitamin E deficiency.

• Dietary sources include vegetable oil, fresh leafy vegetables, egg yolk, legumes, peanuts, and margarine

Fat-Soluble Vitamins3. Vitamin D

• Used for proper skeleton formation and mineral homeostasis.

• It stimulates intestinal absorption of calcium and phosphate for bone growth and metabolism.

• Major dietary sources include irradiated foods and commercially prepared milk. Small amounts are found in butter, egg yolks, liver, sardines, herring, tuna, and salmon.

• Severe deficiency in children lead to the development of rickets.

• In adults, the deficiency leads to under-mineralization of bone matrix in remodeling, resulting in osteomalacia.

Fat-Soluble Vitamins4. Vitamin K “koagulation”

• Essential for the formation of prothrombin and at least five other coagulation proteins, including factors VII, IX, and X and proteins C and S.

• Vitamin K is synthesized by intestinal bacteria, 50%; dietary sources are cabbage, cauliflower, spinach and other leafy vegetables, liver, soybeans, and vegetable oils.

• Vitamin K deficiency may be caused by antibiotic therapy

• Both PT and APTT are prolonged in vitamin K deficiency.

• In most laboratories, vitamin K is not assayed; however, PT is used as a functional indicator of vitamin K status.

Water-Soluble Vitamins1. Thiamine (vitamin B1)

• Acts as a coenzyme in decarboxylation reactions in major carbohydrate pathways.

• Absorbed from food in the small intestine and excreted in the urine.

• Chronic thiamine deficiency lead to beriberi. “I can’t ..I can’t”

• Decreased intake, impaired absorption, and increased requirements all appear to play a role in the development of thiamine deficiency in persons with alcoholism.

• Thiamine functional activity is best measured by erythrocyte transketolase (ETK) activity, before and after the addition of thiamine pyrophosphate (TPP).

Water-Soluble Vitamins2. Riboflavin (vitamin B2) A component of two coenzymes, flavin

mononucleotide and flavin adenine dinucleotide (FAD).

Catalyze various oxidation-reduction reactions.

Absorbed in the small intestine and excreted in the urine.

Found in milk, liver, eggs, meat, and leafy vegetables.

Riboflavin deficiency occurs with other nutritional deficiencies, alcoholism, and chronic diarrhea and malabsorption.

Reduced glutathione reductase activity greater than 40% is an indication of deficiency.

Water-Soluble Vitamins3. Pyridoxine (vitamin B6)

Vitamin B6 is three related compounds: pyridoxine, occurring mainly in plants; and pyridoxal and pyridoxamine, which are present in animal products.

Readily absorbed from the intestinal tract, and excreted in the urine in the form of metabolites.

Vitamin B6 deficiency more commonly seen in patients deficient in several B vitamins.

Those particularly at risk for deficiency are patients with uremia, liver disease, absorption syndromes, malignancies, or chronic alcoholism.

Water-Soluble Vitamins4. Niacin (Vitamin B3) The requirement for niacin in humans is

met, to some extent, by the conversion of dietary tryptophan to niacin.

Niacin functions as a component of the two coenzymes (NAD) and (NADP) “eg; lipid and fatty acid metabolism”.

Pellagra, the clinical syndrome resulting from niacin deficiency, is associated with diarrhea, dementia, dermatitis, and death.

To decrease lipid levels, pharmacologic doses of nicotinic acid are given therapeutically

Water-Soluble Vitamins5. Folate

Act as coenzymes in various one-carbon transfer reactions.

Absorbed in the jejunum, and the excess is excreted in the urine and feces.

Large quantities of folate are also synthesized by bacteria in the colon.

Boiling food and using large quantities of water result in folate destruction.

The major clinical symptom of folate deficiency is megaloblastic anemia.

Water-Soluble Vitamins

Chemical indices of deficiency are in order of occurrence, low serum folate, hypersegmentation of neutrophils, low erythrocyte folate, macro-ovalocytosis, megaloblastic marrow, and anemia.

Folate Cont. ….

Folate requirement is increased during pregnancy and especially during lactation.

Supplementation of folate in pregnant women reduces the incidence of fetal neural tube defects.

Increased folate requirement include hemolytic anemia, iron deficiency, prematurity, and multiple myeloma.

Folate levels may be measured in serum using a microbiologic assay with Lactobacillus casei or a competitive protein-binding assay for levels in serum and erythrocytes.

Water-Soluble Vitamins6. Vitamin B12o Vitamin B12 (cobalamin) refers to a large

group of cobaltcontaining compounds.

o Intestinal absorption of vitamin B12 takes place in the ileum and is mediated by a unique binding protein called intrinsic factor, which is secreted by the stomach.

o The primary dietary source for vitamin B12 are from animal products (e.g., meat, eggs, and milk).

o The average daily diet contains 3–30 µg of vitamin B12, of which 1–5 µg is absorbed.

o The term pernicious anemia is now most commonly applied to vitamin B12 deficiency resulting from lack of intrinsic factor.

Water-Soluble Vitamins

Deficiency of B12 can occasionally occur in strict vegetarians because of dietary deficiency of B12.

Vitamin B12 Cont. …..

also occurs in individuals infected with fish tapeworm or because of malabsorption diseases, such as sprue or celiac disease.

Deficiency of vitamin B12 causes two major disorders megaloblastic anemia (pernicious anemia) and a neurologic disorder called combined systems disorder.

The most common methods for determination of vitamin B12 are the competitive protein-binding RIAs.

Water-Soluble Vitamins7. Biotin (Vitamin B7)

Biotin is a coenzyme for several enzymes that transport carboxyl units in tissue and plays an integral role in gluconeogenesis, lipogenesis, and fatty acid synthesis.

Dietary biotin is absorbed in the small intestine, but it is also synthesized in the gut by bacteria.

Biotin deficiency can be produced by ingestion of large amounts of avidin, found in raw egg whites that bind to biotin.

Biotin deficiency has been noted in patients receiving long-term parenteral nutrition and in infants with genetic defects of carboxylase and biotinidase enzymes.

Water-Soluble Vitamins

8. Pantothenic Acid (from Greek for “everywhere”)

Assays had been performed using microbiology functional assay and the Lactobacillus organism, isotopic dilution, chemiluminescent, and photometric assays.

Dietary sources include liver and other organ meats, milk, eggs, peanuts, legumes, mushrooms, salmon, and whole grains.

Pantothenate is metabolically converted to 4-phosphopantetheine, which becomes covalently bound to either serum acyl carrier protein or coenzyme A.

A growth factor occurring in all types of animal and plant tissue was first designated vitamin B3 and later named pantothenic acid.

Water-Soluble Vitamins9. Ascorbic Acid (Vitamin C)

• A strong reducing compound that has to be acquired via dietary ingestion.

• Major dietary sources include fruits (especially citrus) and vegetables (e.g., tomatoes, green peppers, cabbage, leafy greens, and potatoes).

• Important in formation and stabilization of collagen, and increases the absorption of certain minerals, such as iron.

• The deficiency state, known as scurvy, is characterized by hemorrhagic disorders, including swollen, bleeding gums and impaired wound healing and anemia.

Water-Soluble Vitamins

• Ascorbic acid requirements are more increased with acute stress injury and chronic inflammatory states, but are also increased with pregnancy and oral contraceptive use.

Ascorbic Acid Cont. …..• Drugs known to increase urinary excretion of ascorbate

include aspirin, aminopyrine, and others.

• Excessive intake may interfere with vitamin B12 metabolism.

• The most widely used assay for ascorbic acid is the 2,4-dinitrophenylhydrazine method. In this procedure, ascorbic acid is first oxidized to dehydroascorbic acid and 2,3-diketogulonic acid with the formation of a colored product that absorbs at 520 nm. HPLC has been developed to give increased sensitivity and specificity.

Water-Soluble Vitamins10. Carnitine• Meat, poultry, fish, and dairy products are the

major dietary sources. Foods of plant origin generally contain little carnitine, except for peanut butter and asparagus.

• Synthesis occurs in liver, brain, and kidney.

• L-Carnitine facilitates entry of long-chain fatty acids into mitochondria for oxidation and energy production.

• The major signs of carnitine deficiency are muscle weakness and fatigue.

• Human deficiency can be either hereditary or acquired—by inadequate intake, increased requirement (pregnancy and breastfeeding), or increased urinary loss (valproic acid therapy).

Mineral metabolism - Calcium/phosphorus Mineral Tests to Monitor

I. One of the most important aspects of TPN monitoring is determining deficiencies and excesses of calcium, phosphorus, and magnesium.

II. Calcium is present in serum in two forms: protein bound, or non-diffusible, and ionized diffusible calcium (physiologically active).

III. Decreased ionized calcium often is caused by an increase in blood pH (alkalosis).

IV. It is important to monitor ionized serum calcium and blood pH, especially in a patient on TPN.

Mineral metabolism - Calcium/phosphorus Mineral Tests to Monitor Cont. …..

V. Intracellular phosphate is necessary to promote protein synthesis and other cellular functions.

VI. Severe hypophosphatemia has been reported in patients undergoing prolonged TPN.

VII.Low levels of magnesium can cause tetany, whereas high levels can increase cardiac atrioventricular conduction time.

Trace Minerals / Trace Elements to Monitor

1. Copper

Copper is a component of

1. Cytochrome oxidase enzyme (ATP generation).2. Dopamine monooxygenase (neuron activity and transmission

of impulse).3. Superoxide dismutase (reduce the free radical superoxide).4. Ceruloplasmin (convert iron from the Fe+3 state to the

absorbed Fe+2).

The diagnosis of copper deficiency is confirmed when both serum copper and ceruloplasmin (the copper binding glycoprotein) are low.

Low copper levels have also been reported in malabsorption syndrome, protein-wasting intestinal diseases, nephrotic syndrome, severe trauma, anemia, and burns.

Trace Minerals / Trace Elements to Monitor

1. Copper Cont. ……

The accumulation of copper in the liver can go into hepatitis, then a fibrosis, and then a cirrhosis if not treated with chelation and diet restricted in copper content.

Methods for copper measurement include atomic absorption for serum and urinary copper measurements. Indirect copper measurements are attained by measuring the ceruloplasmin levels.

2. Zinc

Trace Minerals / Trace Elements to Monitor

Metalloenzymes using zinc include carbonic anhydrase, alkaline phosphatase (ALP), thymidine kinase, alcohol dehydrogenase, and RNA and DNA polymerases.

Biochemical functions of zinc-containing metalloenzymes includes protein synthesis, gene expression, transport processes, immunologic reactions, and wound healing.

Patients on TPN may develop acute zinc deficiency.

Zinc transport in serum uses albumin primarily and 2-amacroglobulin.

Zinc is required for vision, taste, and smell functions. It promotes tissue repair, connective tissue synthesis, bone growth, and insulin synthesis.

2. Zinc Cont. ….

Trace Minerals / Trace Elements to Monitor

Malnutrition, infertility, inflammation, and hair loss are often treated with zinc supplementation.

Methods for zinc analysis include atomic absorption spectroscopy, inductively coupled atomic plasma (ICP) emission spectroscopy, and HPLC.

Red cells contain zinc, so hemolysis elevates zinc plasma values.

Trace Minerals / Trace Elements to Monitor

3. Iron Enzymes requiring iron cofactor include aconitase,

succinate dehydrogenase, and isocitrate dehydrogenase from the TCA cycle.

Catalase and myeloperoxidase found in neutrophils both require iron as cofactor.

Ribonucleotide reductase and xanthine oxidase involved in RNA and DNA metabolism.

Excess iron has been associated with increasing the amount of free radicals and infection in patients.

Deficiencies of iron are associated with anemia.

4. Selenium

Trace Minerals / Trace Elements to Monitor

Have an influence on cancer, cardiovascular diseases, diabetes, and arthritis.

Essential cofactor to the antioxidant enzyme glutathione peroxidase, which is involved in neutralizing hydrogen peroxide formed during lipid oxidation in cells.

Functions of selenium in humans include anti-atherogenic effect, anticancer effect, antioxidant, improved fetility, and increasing the immune response.

Excessive selenium can occur with excessive supplementation. Effects include fatigue, irritability, loss of hair and nails, vomiting, nerve damage, and skin rashes.

4. Selenium Cont. …..

Trace Minerals / Trace Elements to Monitor

The cardiomyopathy effects of selenium deficiency are seen in home parenteral nutrition or HPN.

Methods for determining selenium have been flameless atomic absorption spectroscopy or spectrofluorometry.

Elevated values need to be confirmed with a second specimen collection and analysis.