Midterm Exam Thursday, May 3, 3PM or by arrangement pick up labs on Tuesday at 2PM in 129 MI Topics: Intro to Nutrition Assessment Anthropometric Assessment Body Composition Assessment Closed book (< 20 minutes) Theory and principles Lecture and sections of text that support lecture materials Open book/notes/lab reports/calculators (~30 minutes) Be able to do all calculations/assessments you did for labs Know how before coming to class Total test time = 50 minutes May 8 & 10 Glucose tolerance test Fast 6-8 hours before class (no caloric foods after 8AM)

Laboratory Values for Nutritional Assessment David L. Gee, PhD FCSN 442 Nutrition Assessment Laboratory

Biochemical Assessment of Nutritional Status Compared to anthropometric, clinical methods, and dietary intake data, biochemical assessment is Most objective and precise More sensitive However, can be misinterpreted or affected by factors unrelated to stated assessment

Uses of Biochemical Measures Static Tests (direct tests) Measurement of a nutrient or metabolite Blood glucose concentration Blood folic acid concentration Blood calcium concentration May fail to reflect overall nutritional status Blood calcium normal in patients with osteoporosis

Uses of Biochemical Measures Functional Tests (indirect tests) Assesses nutritional status by looking at a function of that nutrient Glucose tolerance test for glucose intolerance Histidine load test (FIGLU) for folate status HIS FIGLU GLU

Uses of Biochemical Measures Validate dietary assessment Protein intake 24-hour urinary nitrogen excretion Energy intake Doubly labeled water method Drink 2 H 2 O + H 2 18 O 2 H 2 O only lost from body as water H 2 18 O lost from body as water or C 18 O 2 CO 2 + H 2 O H 2 CO 3 Collect urine periodically over 3 weeks and measure difference of 2 H 2 O and H 2 18 O Greater the difference, the greater the metabolic rate. Milk intake Plasma levels of C15:0 fatty acids

Understanding lab values Understanding the metabolic basis of the laboratory test Biological sample used Blood, plasma, serum Urine Factors affecting the concentration of the metabolite measured

Example: nitrogen metabolism Amino acid metabolism Urea synthesis in liver From ammonia and aspartic acid Urea excretion in kidneys Questions? What are causes of elevated BUN? (uremia) What are factors that cause urinary urea nitrogen to go up? What are causes of elevated blood ammonia (hyperammonemia)

Assessment of Renal Function: Blood Urea Nitrogen BUN Urea: end product of amino acid metabolism Produced in liver Site of urea cycle Excreted by kidneys Elevated due to renal insufficiency Injured liver results in elevated ammonia concentrations

Other factors affecting [BUN] Dehydration Decreases BUN Severe liver disease Decreases BUN High dietary protein intake No effect 24-hour Urinary urea excretion affected by protein intake Hemodialysis patients Increases between dialysis

Lab Values for Creatinine -Blood creatinine concentration -Urinary creatinine concentration

Serum Creatinine Endproduct of creatine metabolism Excreted by kidneys into urine Blood creatinine concentration Increases in blood creatinine Renal insufficiency Urinary excretion (24hr) proportional to total muscle creatine Proportional to muscle mass Also affected by meat consumption creatine supplementation

Bilirubin Endproduct of heme catabolism Made in spleen, liver, bone marrow Conjugated with glucuronic acid in liver Excreted into bile from liver Elevated bilirubin is neurotoxic Jaundice

Conjugated bilirubin Glucuronic acid Conjugation occurs in liver to enhance water solubility “direct bilirubin

Newborn Jaundice

Bilirubin Indirect Bilirubin free bilirubin (unbound) circulating form Production of bilirubin from hemoglobin occurs in spleen, liver, and bone marrow Direct Bilirubin bilirubin conjugated (bound) to other compounds (glucuronic acid) made in liver excreted in bile

Elevated Direct Bilirubin Post hepatic jaundice Causes by obstruction in liver obstruction in bile duct

Elevated Indirect Bilirubin Pre-hepatic jaundice Causes: excessive hemolysis liver disease hepatitis premature infants underdeveloped liver