Biochemical Assessment and Nutrition Assessment - Course Notes PDF

Biochemical Assessment and Nutrition Assessment What is biochemical assessment? The analysis of patient specimens, which are compared to reference standards. Advantages: Routine lab data available in medical records. Objective measure used in nutrition assessment. Limitations:...

Biochemical Assessment and Nutrition Assessment What is biochemical assessment? The analysis of patient specimens, which are compared to reference standards. Advantages: Routine lab data available in medical records. Objective measure used in nutrition assessment. Limitations: May not be specific evidence of nutrition status Variation in “normal” range based on age, sex, pregnancy. Variation based on disease state, condition. Variation based on lab differences. Additional Considerations Serial measures more informative Remember, serial means measures taken over time (think of a series of measures) Treat the patient, not the lab value. Improvements in labs do not always results in clinical improvements (patient or disease feeling/being better) Tissue stores of micronutrients are more important to nutrition status than blood values Types of Specimens Whole blood: Collected with an anti-coagulant in the tube (Contains RBCs, WBCs, and platelets.) Serum: Fluid obtained after blood is clotted and clot removed. Does not contain RBCs or WBCs Plasma: Transparent liquid component of blood. Serum plus fibrinogen. Collected in tubes with anti-coagulant (like heparin) Urine: Contains excreted metabolites Stool: May be important in determining malabsorption. Many Others: breath, saliva, sweat, etc. Clinical Chemistry Panels Basic metabolic panel (BMP): Includes 8 tests: glucose, calcium, sodium, potassium, CO2, chloride, BUN, creatinine Chem 7: Same as BMP minus calcium Comprehensive metabolic panel (CMP): Includes: BMP + six tests: Albumin, Total protein, Alkaline Phosphatase (ALP), Alanine amino-transferase (ALT), aspartate amino-transferase (AST), Bilirubin Chem-20: CMP + GGT, LDH, Chol, Uric acid Complete blood count: Count of cells in the blood Serum Electrolytes (Na, K, Cl, Ca, Phos, CO2, HCO3) May be monitored in nutrition support patients, kidney dz, pulmonary dz, alkalosis, acidosis Na 136-145 mEq/L; K 3.5-5.5 mEq/L; Cl 95-105 mEq/L Sodium: Hyponatremia (low Na) and hypernatremia (high Na) reflect problems with sodium concentration and total-body water Typically increases with hypovolemia/dehydration Typically decreases with hypervolemia Non-specific—may be normal or increased in these conditions See pg 123-124 in Handbook (Table 6.10) Serum Electrolytes (Potassium) Major intracellular Cation; Serum levels do not correlate with body stores Hypokalemia (low K) possible causes: Serum levels do not correlate with body stores Possible causes—GI losses (diarrhea, vomiting) Medications Refeeding syndrome Others Hyperkalemia (high K) possible causes: Kidney (renal) failure Medications Others Serum Electrolytes (Ca, Phos) Calcium (8.5-10.5 mg/dl) Does not correlate well with body stores May be increased in vitamin D deficiency May be decreased in kidney disease, hypoparathyroidism Phosphorus (3-4.5 mg/dl): May be increased with hypoparathyroidism, chronic antacid ingestion, kidney disease May be decreased with vitamin D defiency, refeeding syndrome Blood Proteins Albumin (3.5-5 mg/dl): May be decreased in liver disease or in acute inflammatory diseases In unstressed starvation, levels are often normal because of less catabolism Transferrin (200-400 mg/dl) Binds and transports iron Inversely correlated with body’s iron stores (elevations may be early sign of iron deficiency) >100 mg/dl (severe depletion) Liver disease, zinc deficiency can also decrease it Prealbumin (16-40 mg/dl) Carrier for thyroxin Acute phase response, hyperthyroidism may decrease it Indicators of Acute Inflammation C-reactive protein: Inflammatory biomarker: acute inflammation May increase above 10 mg/dl in acute infection or stress High-sensitivity CRP: Inflammatory biomarker: chronic, lower-level inflammation Used to measure levels between 0-10 mg/dl The Stress Response and Acute Phase Reactants/Proteins What happens when someone becomes acutely ill or is injured? The body mounts an inflammatory response Cytokines are released Positive acute phase reactants/proteins my increase rapidly (CRP) Negative acute phase reactants/proteins may rapidly decline in circulation Examples: Alb, PAB, Transferrin, RBP Hyper-metabolic pathways are up-regulated. Past Key Indicators for Malnutrition Acute Phase Proteins: Albumin, pre-albumin, retinol binding protein, transferrin What is the problem with using these to assess malnutrition in the hospital?  Are Acute Phase Proteins Highly Sensitive Indicators of Malnutrition? Indicators of Glucose (Glu, CBG, Hgb A1C) Glucose (70-99 mg/dl): May be used to diagnose diabetes; monitored in nutrition support patients, those with diabetes Fasting Glucose: 100-125 mg/dl = possible prediabetes ≥ 126 mg/dl = diabetes Hemoglobin A1c (normal is