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Solving Puzzles of Laboratory Data Interpretation. Evaluation of Visceral Protein Status. Affected by numerous other factors, including hydration status, chronic illness, acute phase response May have low sensitivity/specificity

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evaluation of visceral protein status
Evaluation of Visceral Protein Status
  • Affected by numerous other factors, including hydration status, chronic illness, acute phase response
  • May have low sensitivity/specificity
  • However, low serum albumin and acute phase proteins are associated with increased complications and length of stay in hospitalized patients; probably an index of severity of illness
preoperative albumin as a predictor of risk in elective surgery patients
Preoperative Albumin as a Predictor of Risk in Elective Surgery Patients
  • Retrospective review of 520 patients with preoperative serum albumin measurements
  • Preoperative albumin correlated inversely with complications, length of stay, postoperative stay, ICU stay, mortality, and resumption of oral intake
  • S. albumin levels <3.2 were predictive of risk
        • Kudsk et al, JPEN, 2003
role of visceral protein measurement in nutrition screening and assessment
Role of Visceral Protein Measurement in Nutrition Screening and Assessment
  • Low values in critically ill patients a measure of severity of illness
  • Is a valuable predictor of morbidity/mortality in hospitalized and LTC patients
  • Can be used to identify elective surgery patients who could benefit from nutrition intervention
  • Sequential measurements may reflect changes/improvement of nutritional status
serum albumin
Serum Albumin
  • Normal: 3.5-5.0 g/dL
  • Half-life approximately 14-20 days
  • Decreased by: APR (in inflammation, infection, injury, surgery, cancer); severe liver failure, redistribution, intravascular volume overload, third spacing, pregnancy; losses in nephrotic syndrome, burns, protein losing enteropathies, exudates
  • Increased by: intravascular volume depletion, intravenous albumin or plasminate, anabolic steroids
serum transferrin
Serum Transferrin
  • Normal: 200-400 mg/dL
  • Half-life: approximately 8-10 days
  • Decreased by: APR, chronic or end-stage liver disease, uremia, protein-losing states, intravascular volume overload, high-dose antibiotic tx, iron overload, severe zinc deficiency, PCM
  • Increased by: iron deficiency, chronic blood loss, pregnancy, intravasclar volume depletion, acute hepatitis, oral contraceptives, estrogen
prealbumin transthyretin thyroxin binding prealbumin
Prealbumin (transthyretin, Thyroxin-Binding Prealbumin)
  • Normal: 16-40 mg/dL
  • Half-life: 2-3 days
  • Decreased by: APR, end stage liver disease, untreated hyperthyroidism, nephrotic syndrome, severe zinc deficiency
  • Increased by: moderate increase in acute or chronic renal failure, anabolic steroids, possibly glucocorticoids
retinol binding protein
Retinol-Binding Protein
  • Normal: 2.7-7.6 mg/dL
  • Half-life: approximately 12 hours
  • Decreased by: hyperthyroidism, chronic liver disorders, APR, cystic fibrosis, vitamin A or severe zinc deficiency
  • Increased by renal failure, glucocorticoids, acute or early liver damage
c reactive protein crp
C-Reactive Protein (CRP)
  • Monitors the presence, intensity, and recovery from an inflammatory process
  • Good indicator of the APR and sensitive for diagnosing infection
  • Not useful as a nutritional marker, however can be used to evaluate effect of APR on nutritional markers such as visceral proteins
slide10
CRP
  • Normal: <0.8 mg/dL (<8 mg/L)
  • Rises within hours of an acute stimulus
  • Decrease in CRP of >50 mg/L between admission and day 4 is a good predictor of recovery
  • As the ACP wanes, expect to see CRP decline
  • As CRP declines, sensitive visceral proteins should increase
lipoprotein profile
Lipoprotein Profile
  • Measures total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides
  • 8-12 hour fast allows chylomicrons to clear
  • Friedenwald formula for calculating LDL-C = (TC) – (HDL-C) – (TG/5)
lipoprotein profile confounders
Lipoprotein Profile Confounders
  • Lipids decline significantly 24 hours after an acute MI or other event
  • Lipid profiles should be done either within 24 hours of an acute myocardial event or several weeks out
  • Lipids measured after major surgery will be artificially low
  • Very low total cholesterol may indicate malnutrition
  • Estrogen decreases serum cholesterol; pregnancy and menopause increase serum cholesterol
atp iii screening guidelines
ATP III Screening Guidelines

New Recommendation for Screening/Detection

  • Complete lipoprotein profile preferred
    • Fasting total cholesterol, LDL, HDL, triglycerides
  • Secondary option
    • Non-fasting total cholesterol and HDL
    • Proceed to lipoprotein profile if TC 200 mg/dL or HDL <40 mg/dL
three categories of risk that modify ldl cholesterol goals
Risk Category

CHD and CHD riskequivalents

Multiple (2+) risk factors

Zero to one risk factor

LDL Goal (mg/dL)

<100

<130

<160

Three Categories of Risk that Modify LDL-Cholesterol Goals
major risk factors for chd
Major Risk Factors for CHD
  • Cigarette smoking
  • Hypertension (BP >140/90 mmHg or on antihypertensive medication)
  • Low HDL cholesterol (<40 mg/dL)
  • Family history of premature CHD (CHD in male first degree relative <55 years;
  • CHD in female first degree relative <65 years)
  • Age (men >45 years; women >55 years)
chd risk equivalents
CHD Risk Equivalents
  • Clinical CHD
  • Symptomatic carotid artery disease
  • Peripheral arterial disease
  • Abdominal aortic aneurysm.
  • Diabetes
atp iii lipid and lipoprotein classification
ATP III Lipid and Lipoprotein Classification

LDL Cholesterol (mg/dL)

<100 Optimal

100–129 Near optimal/above optimal

130–159 Borderline high

160–189 High

190 Very high

atp iii lipid and lipoprotein classification continued
ATP III Lipid and Lipoprotein Classification (continued)

HDL Cholesterol (mg/dL)

<40 Low

60 High

atp iii lipid and lipoprotein classification continued19
ATP III Lipid and Lipoprotein Classification (continued)

Total Cholesterol (mg/dL)

<200 Desirable

200–239 Borderline high

240 High

specific dyslipidemias elevated triglycerides
Specific Dyslipidemias: Elevated Triglycerides

Classification of Serum Triglycerides

  • Normal <150 mg/dL
  • Borderline high 150–199 mg/dL
  • High 200–499 mg/dL
  • Very high 500 mg/dL
causes of high triglycerides 150 mg dl
Causes of High Triglycerides(150 mg/dL)
  • Obesity and overweight
  • Physical inactivity
  • Cigarette smoking
  • Excess alcohol intake
causes of high triglycerides
Causes of High Triglycerides
  • High carbohydrate diets (>60% of energy intake)
  • Several diseases (type 2 diabetes, chronic renal failure, nephrotic syndrome)
  • Certain drugs (corticosteroids, estrogens, retinoids, higher doses of beta-blockers)
  • Various genetic dyslipidemias
elevated triglycerides
Elevated Triglycerides

Non-HDL Cholesterol: Secondary Target

  • Primary target of therapy: LDL cholesterol
  • Achieve LDL goal before treating non-HDL cholesterol
  • Therapeutic approaches to elevated non-HDL cholesterol
non hdl cholesterol
Non-HDL Cholesterol
  • Secondary target of therapy when serum triglycerides are 200 mg/dL (esp. 200–499 mg/dL)
  • Non-HDL cholesterol = VLDL + LDL cholesterol= (Total Cholesterol – HDL cholesterol
  • Non-HDL cholesterol goal: LDL-cholesterol goal + 30 mg/dL)
comparison of ldl cholesterol and non hdl cholesterol goals for three risk categories
Comparison of LDL Cholesterol and Non-HDL Cholesterol Goals forThree Risk Categories

Risk Category

LDL-C Goal

(mg/dL)

Non-HDL-CGoal (mg/dL)

CHD and CHD Risk Equivalent

(10-year risk for CHD >20%

<100

<130

Multiple (2+) Risk Factors and

10-year risk <20%

<130

<160

0–1 Risk Factor

<160

<190

specific dyslipidemias causes of low hdl cholesterol 40 mg dl
Specific Dyslipidemias: Causes of Low HDL Cholesterol (<40 mg/dL)
  • Elevated triglycerides
  • Overweight and obesity
  • Physical inactivity
  • Type 2 diabetes
  • Cigarette smoking
  • Very high carbohydrate intakes (>60% energy)
  • Certain drugs (beta-blockers, anabolic steroids, progestational agents)
risk can vary considerably with same tc
TC: 200 mg/dL

HDL: 25 mg/dL

LDL: 160 mg/dL

TG: 75 mg/dL

TC: 200 mg/dL

HDL: 70 mg/dL

LDL: 100 mg/dL

TG: 150 mg/dL

Risk Can Vary Considerably with Same TC
risk can vary considerably with same tc28
TC: 200 mg/dL

HDL: 25 mg/dL

LDL: 160 mg/dL

TG: 75 mg/dL

This person would be at high risk for CHD based on lipid profile

TC: 200 mg/dL

HDL: 70 mg/dL

LDL: 100 mg/dL

TG: 150 mg/dL

This person would be at low risk for CHD based on lipid profile

Risk Can Vary Considerably with Same TC
risk can vary considerably with same tc29
Risk Can Vary Considerably with Same TC
  • TC: 200 mg/dL
  • LDL-C: 120 mg/dL
  • HDL-C: 30 mg/dL
  • TG: 450 mg/dL
  • 42 y.o. man, smoker
  • What is his LDL goal?
risk can vary considerably with same tc30
Risk Can Vary Considerably with Same TC
  • TC: 200 mg/dL
  • LDL-C: 120 mg/dL
  • HDL-C: 30 mg/dL
  • TG: 450 mg/dL
  • 42 y.o. man, smoker
  • What is his LDL goal?
  • A: he has 3 risk factors (male, smoker, low HDL), non-CAD, so his LDL goal is 130 mg/dL
risk can vary considerably with same tc31
Risk Can Vary Considerably with Same TC
  • TC: 200 mg/dL
  • LDL-C: 120 mg/dL
  • HDL-C: 30 mg/dL
  • TG: 450 mg/dL
  • If TG are >200 mg/dL, determine non-HDL cholesterol
  • TC – HDL = 170 mg/dL
  • What is his goal?
risk can vary considerably with same tc32
Risk Can Vary Considerably with Same TC
  • TC: 200 mg/dL
  • LDL-C: 120 mg/dL
  • HDL-C: 30 mg/dL
  • TG: 450 mg/dL
  • Non-HDL-C goal is LDL goal + 30
  • Patient has 2+ risk factors so goal is <130 mg/dL
  • Non-HDL goal is 160 mg/dL
blood urea nitrogen
Blood Urea Nitrogen
  • Normal value: 10-20 mg/dl
  • High: prerenal causes (CHF), renal obstruction, excessive intake of protein, GI bleeding, catabolic state, dehydration, glucocorticoid therapy; not specific to renal disease, though most renal diseases cause  BUN
  • Low: inadequate dietary protein, severe liver failure
creatinine
Creatinine
  • Normal value: 0.7-1.2 mg/dL
  • Breakdown product of creatine, an important component of muscle
  • Production depends on muscle mass, which varies very little.
  • Excreted exclusively by the kidneys
  • Level in the blood is proportional to the glomerular filtration rate.
  • A more sensitive test of kidney function than BUN because kidney impairment is almost the only cause of elevated creatinine.
creatinine35
Creatinine
  • Rising creatinine may indicate impending renal failure
  • Abnormal values appear late in chronic renal failure
  • Baseline creatinine will be low if patient muscle mass is low
  • Rise of 0.3 to 0.5 mg/dL/day is a clinically significant rise
bun to creatinine ratio
BUN to Creatinine Ratio
  • Normal range 10-20:1
  • In kidney disease, the BUN:creatinine ratio is usually normal
  • Increased BUN to creatinine ratio is commonly caused by intravascular depletion (sodium, water and urea are retained by the body; creatinine is excreted)
bun to creatinine ratio37
BUN to Creatinine Ratio
  • High BUN:creatinine ratio may also be caused by protein loads in PN or EN; usually does not exceed 30 mg/dL
  • Can also be caused by renal obstruction (e.g. kidney stones), poor renal perfusion or acute renal failure; medications including diuretics, corticosteroids,
  • Very high levels may be caused by GI or respiratory bleeding
dehydration
Dehydration
  • Excessive loss of free water
  • Loss of fluids causes an increase in the concentration of solutes in the blood (increased osmolality)
  • Water shifts out of the cells into the blood
  • Causes: prolonged fever, watery diarrhea, failure to respond to thirst, highly concentrated feedings, including TF
assessment of hydration status physical signs of underhydration
Input < output over time

Decreased weight

Sunken, dry eyes

Dark-colored urine; oliguria

Dry mucous membranes

Sticky saliva

Poor skin turgor

Cool, pale, clammy skin

Assessment of Hydration StatusPhysical Signs of Underhydration
assessment of hydration status laboratory signs of underhydration
Elevated sodium

Elevated chloride

Elevated BUN

Elevated creatinine

Elevated hemoglobin

Elevated hematocrit

Elevated serum osmolality

Elevated urine specific gravity

Assessment of Hydration StatusLaboratory Signs of Underhydration
laboratory values and hydration status
Laboratory Values and Hydration Status

Adapted from Charney and Malone. ADA Pocket Guide to Nutrition Assessment, 2004.

laboratory values and hydration status42
Laboratory Values and Hydration Status

Adapted from Charney and Malone. ADA Pocket Guide to Nutrition Assessment, 2004.

laboratory values and hydration status43
Laboratory Values and Hydration Status

Adapted from Charney and Malone. ADA Pocket Guide to Nutrition Assessment, 2004.

laboratory values and hydration status44
Laboratory Values and Hydration Status

Adapted from Charney and Malone. ADA Pocket Guide to Nutrition Assessment, 2004.

laboratory values and hydration status45
Laboratory Values and Hydration Status

Adapted from Charney and Malone. ADA Pocket Guide to Nutrition Assessment, 2004.

laboratory values and hydration status46
Laboratory Values and Hydration Status

Adapted from Charney and Malone. ADA Pocket Guide to Nutrition Assessment, 2004.

treatment of dehydration
Treatment of Dehydration
  • Use hypotonic IV solutions such as D5W
  • Offer oral fluids
  • Rehydrate gradually
lab data in refeeding syndrome
Check potassium, phosphorus, magnesium prior to initiation of feeding in high-risk individuals

A rapid decline along with fluid retention, derangements of glucose metabolism is seen with refeeding

Correct low levels prior to initiation of hypocaloric feeds (<BEE x 1) and monitor daily until stable at full feeds

At risk pts are those with anorexia nervosa, alcoholism, prolonged IV hydration or fasting

Lab Data in Refeeding Syndrome
stool studies c difficile
Stool Studies: C. Difficile
  • C. difficile associated diarrhea, cramps, fever, leukocytosis usually occurs within 1-2 mos of antibiotic use
  • Cytotoxin B is the most specific assay (toxin in stool); may need to test several times
  • Treatment: metronidazole or oral vancomycin
  • Avoid antidiarrheals
stool studies fat malabsorption
Stool Studies: Fat Malabsorption
  • Sudan III stain: qualitative study, can use random stool sample; positive results are increased (2+) or markedly increased (3+); more reliable for moderate to severe steatorrhea
  • Fecal fat test: pt consumes 80-100 g fat/day a 72-H stool collection is made; <7 g fat/24-h stool collection is normal
hemoglobin
Hemoglobin
  • Normal values vary with age and gender
  • Decreased in anemia states d/t iron deficiency, thalassemia, pernicious anemia, liver disease, hypothyroidism, hemorrhage, hemolytic anemia
  • Increased in polycythemia vera, CHF, COPD
rbc indices
RBC Indices
  • MCV: mean corpuscular volume
  • MCHC: mean corpuscular hemoglobin concentration
  • MCH: mean corpuscular hemoglobin
  • Used to characterize anemias
slide53
MCV
  • Relates to the size of the average red blood cell
  • Macrocytic anemias: MCV 100-150 fL
  • Microcytic anemia: MCV<82 fL
  • Normal: 82-100 fL
  • Helps identify cause of anemias, e.g. macrocytic may be due to B12 or folic acid deficiency; microcytic may be iron deficiency or hemorrhage
slide54
MCHC
  • Average concentration of Hb in the red blood cells
  • Decreased in hypochromic anemias due to
    • Iron deficiency
    • Chronic blood loss
    • Some thalassemias
slide55
MCH
  • Mean weight of Hb per RBC
  • Helps in diagnosing severely anemic patients
  • Decrease: associated with microcytic anemia
  • Increase: in macrocytic anemias and newborns
slide56
RDW
  • Red cell size distribution width
  • Indication of abnormal variation in the size of RBCs
  • Can distinguish anemia of chronic disease (low MCV, normal RDW) from early iron-deficiency anemia (low MCV, high RDW)
  • Increased RDW in iron deficiency, B12 or folate deficiency, hemolytic anemia
  • Normal in ACD, acute blood loss, aplastic anemia, sickle cell
diabetic ketoacidosis dka vs hyperosmolar hyperglycemic state hhs
Diabetic Ketoacidosis (DKA) vs Hyperosmolar Hyperglycemic State (HHS)
  • DKA is seen most frequently in type 1 diabetes
  • HHS is seen most frequently in type 2 diabetes
  • Ketosis is also seen in alcoholism, starvation, very low carbohydrate diets, and up to 30% of first morning urine samples during pregnancy
ptt and inr
PTT and INR
  • Prothrombin is a protein produced by the liver for the clotting of blood
  • Depends on adequate Vitamin K intake and absorption
  • Prothrombin time is the time it takes to convert prothrombin to thrombin
  • INR means International Normalized Ratio
  • It is a ratio of the patient’s PT to that of International Reference Thromboplastin
ptt and inr67
PTT and INR
  • Are used often to evaluate the effectiveness of anticoagulant therapy with drugs such as heparin or coumarin
  • It is critical to stabilize INR so that the patient doesn’t clot or hemorrhage
  • High INR means more anticoagulation and greater risk of bleeding; low INR means higher risk of clotting
  • INR target is usually 2.0 to 3.0 depending on patient condition
factors that interfere with inr
Factors that Interfere with INR
  • Ingestion of excessive leafy green vegetables (vitamin K), promoting more rapid blood clotting (low INR)
  • Alcoholism prolongs clotting (high INR)
  • Diarrhea and vomiting prolongs clotting (high INR)
  • Technique of blood draw
factors that interfere with inr69
Factors that Interfere with INR
  • Medications: antibiotics, aspirin, cimetidine, isoniazid, plenothiazides, cephalosporins, cholestyramines, phenylbutazone, metronidazole, oral hypoglycemics, phenytoin
  • Prolonged storage of plasma