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Chapter Twenty

Chapter Twenty. Laboratory Values and the Older Adult. Meaning of Laboratory Values. Many normal ranges are different for older adults Greater deviation from normal when under stress Return to normal is slower Relationship to clinical status

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Chapter Twenty

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  1. Chapter Twenty Laboratory Values and the Older Adult

  2. Meaning of Laboratory Values • Many normal ranges are different for older adults • Greater deviation from normal when under stress • Return to normal is slower • Relationship to clinical status • Lab values should be evaluated in relationship to individual’s entire clinical situation • Abnormal lab value may indicate a clinical stressor or medication side effect rather than illness

  3. Meaning of Laboratory Values • Routine laboratory evaluations • Complete blood cell count • Serum glucose • Serum creatinine level • Serum electrolytes • Thyroid function tests • Urinalysis • Stool guaiac test

  4. Common Screening Tests • Tuberculin skin test • Negative result <10 mm of induration • Screening method for tuberculosis • May need to be repeated 1 week later • Urinalysis • Appearance—clear yellow/straw • Specific gravity—1.005–1.020 • pH—4.5–8.0 • Negative for glucose, ketones, blood, bilirubin

  5. Common Screening Tests • Urinalysis (cont.) • Types of specimens • Mid-stream clean catch • Fasting • 24-hour • Send specimen to lab within 10 minutes or keep refrigerated

  6. Common Screening Tests • Stool for occult blood • Negative result—absence of test color • Test three specimens and two different sections of each stool • Avoid red meat, vitamin C intake, iron supplements, and aspirin 2 to 3 days before and during stool collection

  7. Hematological Indicators • Complete blood count • Values do not change with age • Red blood cell count • Men—5.4 ± 0.9 × 1012/L • Women—4.8 ± 0.6 × 1012/L • Diagnose anemia, polycythemia, other bone marrow abnormalities

  8. Hematological Indicators • Complete blood count (cont.) • Hemoglobin • Men—14–18 g/dL • Women—12–16 g/dL • Increase—polycythemia, dehydration • Decrease—anemia, recent hemorrhage, fluid retention, kidney disease

  9. Hematological Indicators • Complete blood count (cont.) • Hematocrit • Men—47.0 ≠ 5.0% • Women—42.0 ≠ 5.0% • Measures percentage by volume or packed RBC in whole blood • Increased—polycythemia • Decreased—anemia, hemodilution, bone marrow disease

  10. Hematological Indicators • Complete blood count (cont.) • RBC indices • MCV 90 ± 7 fl • MCH 29 ± 2 pg • MCHC 34 ± 2% • Aid in diagnosis and classification of anemias

  11. Hematological Indicators • Complete blood count (cont.) • White blood cell count • 4.5–11.0 ×109/L • Used to identify infectious or inflammatory processes, monitor response to chemotherapy and radiation therapy • Increased—infection, leukemia, inflammation • Decreased—bone marrow depression, viral infection

  12. Hematological Indicators • Complete blood count (cont.) • White blood cell differential • Neutrophils 1.8–7.7 ×109/L or 30%–60% • Eosinophils 0–0.45 ×109/L or 1%–4% • Basophils 0–0.20 ×109/L or 0%–0.5% • Lymphocytes 1.0–4.8 ×109/L or 25%–35% • Monocytes 0–0.8×109/L or 1%–4.0%

  13. Hematological Indicators • Complete blood count (cont.) • White blood cell differential (cont.) • Used to determine severity of infection, detect allergic reactions, identify various leukemias

  14. Hematological Indicators • Complete blood count (cont.) • Platelet count • 130,000–400,000/mL • Required for clot formation and hemostasis • Increased—iron-deficiency anemia, hemorrhage, malignancies, splenectomy • Decreased—bone marrow disease, folic acid or vitamin B12 deficiency, drug side effects

  15. Hematological Indicators • Complete blood count (cont.) • Coagulation • Prothombin time • Normal: 9.5–11.8 s (control ±1 s) • Therapeutic: 1.5–2.0 times normal control • Determined before anticoagulation therapy and monitored throughout therapy

  16. Hematological Indicators • Complete blood count (cont.) • Coagulation • Activated partial thromboplastin time (APTT) • Normal: 25–36 s • Therapeutic: 1.5–2.5 times normal control • Evaluated clotting factors of the intrinsic pathway

  17. Blood Chemistry Indicators • Blood glucose • Fasting: • Normal: 75–115 mg/dL • Diabetes mellitus: 140 mg/dL on at least two occasions • Two hours after eating: • Normal: 140 mg/dL • Impaired glucose tolerance: 140–200 mg/dL • Diabetes mellitus: >200 mg/dl on at least two occasions

  18. Blood Chemistry Indicators • Blood glucose (cont.) • Decreased—side effects of various medications, strenuous exercise • Increased—medication side effects, recent illness or infection • Electrolytes • Sodium • 136–145 mEq/L

  19. Blood Chemistry Indicators • Electrolytes (cont.) • Sodium (cont.) • Hyponatremia • Caused by vomiting, diarrhea, renal disorders, diuretics, congestive heart failure • Hypernatremia • Caused by inadequate fluid intake, diarrhea, diuretics

  20. Blood Chemistry Indicators • Electrolytes (cont.) • Potassium • 3.5–5.0 mEq/L • Hypokalemia • Caused by diuretics, malnutrition, vomiting, diarrhea • Hyperkalemia • Caused by renal failure, injuries, acidosis, diabetes mellitus, several medications

  21. Blood Chemistry Indicators • Electrolytes (cont.) • Calcium 9–10.5 mg/dL • Hypocalcemia • Caused by hypoparathyroid, laxative, chemotherapy, corticosteroids • Hypercalcemia • Caused by hyperparathyroid, thiazide antidiuretics, immobilization, excessive vitamin D, calcium-containing antacids

  22. Blood Chemistry Indicators • Electrolytes (cont.) • Phosphate 3–4.5 mg/dL • Chloride 98–106 mEq/L • End products of metabolism • Blood urea nitrogen (BUN) 10–20 mg/dL • Increased caused by renal disease, urinary tract obstruction, drugs

  23. Blood Chemistry Indicators • End products of metabolism (cont.) • Blood urea nitrogen (cont.) • Decrease caused by severe liver failure, malnutrition, overhydration • Creatinine <1.5 mg/dL • Increase caused by renal disease, diabetic acidosis, starvation, diuretics • High levels indication of renal failure

  24. Blood Chemistry Indicators • End products of metabolism (cont.) • Bilirubin • Total: 0.3–1.0 mg/dL • Direct: 0.1–0.3 mg/dL • Indirect: 0.2–0.7 mg/dL • Uric acid Men: 2.5–8.0 mg/dL Women: 1.5–6.0 mg/dL • Increase caused by loop diuretics, thiazides, starvation, alcohol abuse, chemotherapy

  25. Blood Chemistry Indicators • Liver function tests • ALT 0–35 U/L • Increase caused by liver disease, medications, cholecystitis, trauma, lead ingestion • AST or SGOT 0–35 U/L • Increase caused by myocardial infarction, liver disease, hemolytic anemia, pulmonary emboli

  26. Blood Chemistry Indicators • Liver function tests • LDH 60–100 U/mL

  27. Nutritional Indicators • Protein indicators • Total serum protein 5.5–8.0 g/dL • Increase caused by dehydration, infection, diabetic acidosis, chronic alcoholism • Decreased caused by malnutrition, hepatic disease, renal disease, congestive heart failure • Albumin 3.5–5.5 g/dL • Increased caused by multiple myeloma • Decreased caused by malnutrition, liver and renal disease, collagen diseases, rheumatoid arthritis

  28. Nutritional Indicators • Globulins 2.0–3.0 g/dL • Increase caused by tuberculosis, chronic syphilis, subacute bacterial endocarditis, myocardial infarction, diabetes mellitus • Iron indicators • Iron: Men 80–180 mg/dL Women 60–160 mg/dL • Essential in production and function of hemoglobin

  29. Nutritional Indicators • Iron indicators (cont.) • Ferritin 15–200 ng/mL • Increased in hepatic disease, iron overload, leukemia, chronic renal disease • Decreased in chronic iron deficiency • Total iron-binding capacity • 250–460 mg/dL

  30. Nutritional Indicators • Lipoproteins • Total plasma cholesterol • Desired <200 mg/dL • Borderline 200–239 mg/dL • High 240 mg/dL • High-density lipoprotein HDL • Desired >35

  31. Nutritional Indicators • Lipoproteins • Low-density lipoprotein (LDL) • Desired 130 mg/dL • Borderline 130–159 mg/dL • High 160 mg/dL • Triglycerides • 160 mg/dL

  32. Nutritional Indicators • Lipoproteins • Lipid abnormalities are often familial • Secondary causes • Diets high in saturated fat or cholesterol • Excessive alcohol intake • Estrogen supplements • Smoking • Sedentary lifestyle

  33. Nutritional Indicators • Lipoproteins • Cholesterol is decreased in malnutrition, hyperthyroidism and chronic obstructive pulmonary disease

  34. Drug Monitoring and Toxicology • Drug monitoring is important when toxic and therapeutic range is narrow • Commonly monitored drugs • Digoxin • Therapeutic: 0.5–20 ng/mL • Toxic: 2.5 ng/mL • Signs of toxicity • Visual changes, headache, nausea and vomiting, weakness and fatigue

  35. Drug Monitoring and Toxicology • Commonly monitored drugs (cont.) • Theophylline • Therapeutic: 10–20 µg/mL • Toxic: 20 µg/mL • Signs of toxicity • Anorexia, abdominal discomfort, dizziness, shakiness, restlessness, palpitation, tachycardia, hypotension

  36. Drug Monitoring and Toxicology • Commonly monitored drugs (cont.) • Phenytoin • Therapeutic: 10–20 µg/mL • Toxic: 30 µg/mL • Signs of toxicity • Drowsiness, mental confusion, tremors, photophobia, blurred vision

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