Laboratory Values and the Older Adult Chapter Twenty-Two 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 Laboratory values should not be assessed in isolation Abnormal laboratory value may indicate clinical stressor or medication side effect rather than illness.

Common Screening Tests Tuberculin skin test Borderline positive result 6–10 mm of induration Screening method for tuberculosis Urinalysis Appearance: clear yellow/straw Specific gravity: 1.005–1.035 pH: 4.5–8.0 Negative for glucose, ketones, blood, bilirubin

Common Screening Tests (cont’d) Urinalysis (cont’d) Signs and symptoms of UTI-polyuria, dysuria, frequency of urination Types of specimens Mid-stream clean catch First morning or fasting 24-hour

Common Screening Tests (cont’d) 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 testing.

Hematological Indicators Complete blood count (CBC) Values do not change with age. Red blood cell (RBC) count Men: 4.7–6.1 million cells per mcL Women: 4.2–5.4 million cells per mcL Diagnose anemia, polycythemia, other bone marrow abnormalities

Hematological Indicators (cont’d) Complete blood count (cont’d) Hemoglobin Men: 13.8–17.2 g/dL Women: 12.1–15.1 g/dL Increase: polycythemia, dehydration Decrease: anemia-the most common cause of low hemoglobin, recent hemorrhage, fluid retention, kidney disease

Hematological Indicators (cont’d) Complete blood count (cont’d) Hematocrit Men: 47.0 ± 5.0% Women: 42.0 ± 5.0% Measures percentage of blood volume that packed red blood cells represent Increased: polycythemia Decreased: anemia, hemodilution, bone marrow disease

Hematological Indicators (cont’d) Complete blood count (cont’d) RBC indices MCV Male: 78–100 fL Female: 79–102 fL MCH: 25–35 pg per cell MCHC: 31%–37% Aid in diagnosis and classification of anemias

Hematological Indicators (cont’d) Complete blood count (cont’d) White blood cell count 4,500–10,000 cells per mcL Used to identify infectious or inflammatory processes, monitor response to chemotherapy and radiation therapy Increased: infection, leukemia, inflammation Decreased: bone marrow depression, viral infection

Hematological Indicators (cont’d) Complete blood count (cont’d) White blood cell differential Neutrophils: 1.6–6.7 K/uL or 55%–70% Eosinophils: 0–0.5 K/uL or 1%–5% Basophils: 0–0.3 K/uL or 0%–3% Lymphocytes: 1.2–3.4 K/uL or 16%–46% Monocytes: 0.2-1 K/uL or 4%–11%

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

Hematological Indicators (cont’d) Complete blood count (cont’d) 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

Hematological Indicators (cont’d) Complete blood count (cont’d) Prothrombin time Normal: 11.2–13.2 seconds with an international normalized ratio (INR) of 1 Therapeutic control: 1.5–2 times normal Determined before anticoagulation therapy and used monitored throughout anticoagulant therapy

Hematological Indicators (cont’d) Complete blood count (cont’d) Coagulation Activated partial thromboplastin time (APTT) Normal: 25–36 seconds Therapeutic: 1.5–2.5 times normal control Evaluated clotting factors of the intrinsic pathway APTT evaluates all clotting factors by measuring the time needed to form a clot. It is more sensitive than PTT. APTT is used for monitoring anticoagulation by heparin.

Blood Chemistry Indicators Blood glucose-signs and symptoms are polyuria, polyphasia; polydipsia Fasting Normal: 75–99 mg/dL Older adult: increase 1–2 mg/dL per decade Diabetes mellitus: greater than 125 Glycolated hemoglobin (HgA1C) Normal: less than 5.7% Prediabetes: 5.7%–6.4% Diabetes: greater than 6.5% Goal for diabetics: less than 7%

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

Blood Chemistry Indicators (cont’d) Electrolytes (cont’d) Sodium (cont’d) Hyponatremia-low sodium level Caused by vomiting, diarrhea, renal disorders, diuretics, congestive heart failure Hypernatremia-high sodium level Caused by inadequate fluid intake, diarrhea, diuretics

Blood Chemistry Indicators (cont’d) Electrolytes (cont’d) Potassium: 3.5–5.0 mEq/L-regulates cardiac conduction Hypokalemia-low potassium level Caused by diuretics, malnutrition, vomiting, diarrhea Hyperkalemia-high potassium level Caused by renal failure, injuries, acidosis, diabetes mellitus, several medications and can be manifested by irregular heart beats

Blood Chemistry Indicators (cont’d) Electrolytes (cont’d) 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

Blood Chemistry Indicators (cont’d) Electrolytes (cont’d) Phosphate: 3–4.5 mg/dL Chloride: 98–106 mEq/L-helps to maintain acid-base balance End products of metabolism- along with creatinine are waste products of metabolism that are excreted by the kidneys. Increased levels of serum BUN and creatinine may indicate decreased kidney function Blood urea nitrogen (BUN): 8–25 mg/dL-assesses renal function Increase caused by renal disease, urinary tract obstruction, drugs

Blood Chemistry Indicators (cont’d) End products of metabolism (cont’d) Blood urea nitrogen (cont’d) Decrease caused by severe liver failure, malnutrition, overhydration Creatinine Normal Male: 0.6–1.5 mg/dL Female: 0.6–1.1 mg/dL Increase caused by renal disease, diabetic acidosis, starvation, diuretics High levels indicate renal failure.

Blood Chemistry Indicators (cont’d) End products of metabolism (cont’d) Bilirubin Total: 0.1–1.0 mg/dL Direct: 0.0–0.4 mg/dL Indirect: 0.1–1.0 mg/dL Uric acid-used to help diagnose gout Men: 3.6–8.0 mg/dL (older male: 2–8.5 mg/dL) Women: 2.3–6.0 mg/dL (older female: 2–8 mg/dL) Increase caused by loop diuretics, thiazides, starvation, alcohol abuse, chemotherapy

Blood Chemistry Indicators (cont’d) Liver function tests ALT: 10–56 U/L Increase caused by liver disease, medications, cholecystitis, trauma, lead ingestion AST or SGOT: 5–41 U/L Increase caused by myocardial infarction, liver disease, hemolytic anemia, pulmonary emboli

Cardiac Indicators Creatinine kinase (CK) or Creatine phosphokinase (CPK) Normal Male: 60–400 U/L Female: 40–150 U/L Isoenzyme values CK-I: 0%–1% CK-II: 3% or 0–7.5 ng/mL CK-III: 95%–100%

Cardiac Indicators (cont’d) Troponins Troponin I: greater than 1.5 ng/mL, positive for MI Troponin II: greater than 0.1–0.2 ng/mL, positive for MI B-natriuretic peptide (BNP) Normal reference is less than 100 pg/mL. Greater than 100 pg/mL is positive for CHF.

Nutritional Indicators Protein indicators Total serum protein: 6–8 g/dL Increase caused by dehydration, infection, diabetic acidosis, chronic alcoholism Decrease caused by malnutrition, hepatic disease, renal disease, congestive heart failure Albumin: 3.1–4.3 g/dL Increase caused by multiple myeloma Decrease caused by malnutrition, liver and renal disease, collagen diseases, rheumatoid arthritis

Nutritional Indicators (cont’d) Globulins: 2.6–4.1 g/dL Increase caused by tuberculosis, chronic syphilis, subacute bacterial endocarditis, myocardial infarction, diabetes mellitus Iron indicators Men: 80–180 mg/dL Women: 30–160 mg/dL Essential in production and function of hemoglobin

Nutritional Indicators (cont’d) Iron indicators (cont.) Ferritin: 20–400 ng/mL Increased in hepatic disease, iron overload, leukemia, chronic renal disease Decreased in chronic iron deficiency Total iron-binding capacity: 250–410 mg/dL

Nutritional Indicators (cont’d) Lipoproteins Total plasma cholesterol Desired: <200 mg/dL Borderline: 200–239 mg/dL High: 240 mg/dL High-density lipoprotein (HDL) Desired: >35

Nutritional Indicators (cont’d) Lipoproteins (cont’d) Low-density lipoprotein (LDL) Desired: 130 mg/dL Borderline: 130–159 mg/dL High: 160 mg/dL Triglycerides: 160 mg/dL

Nutritional Indicators (cont’d) Lipoproteins (cont’d) Lipid abnormalities are often familial. Secondary causes Diets high in saturated fat or cholesterol Excessive alcohol intake Estrogen supplements Smoking Sedentary lifestyle

Nutritional Indicators (cont’d) Lipoproteins (cont’d) Cholesterol is decreased in malnutrition, hyperthyroidism, and chronic obstructive pulmonary disease.

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

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

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