Caring for Older Adults Holistically, 4th Edition Chapter Twenty Laboratory Values and the Older...

Caring for Older Adults Holistically, 4th EditionCaring for Older Adults Holistically, 4th Edition

Chapter TwentyChapter Twenty

Laboratory Values and the Older Adult


Meaning of Laboratory ValuesMeaning 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


Meaning of Laboratory ValuesMeaning of Laboratory Values

Routine laboratory evaluations Complete blood cell count Serum glucose Serum creatinine level Serum electrolytes Thyroid function tests Urinalysis Stool guaiac test


Common Screening TestsCommon 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



Urinalysis (cont.) Types of specimens

Mid-stream clean catch Fasting 24-hour

Send specimen to lab within 10 minutes or keep refrigerated



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


Hematological IndicatorsHematological 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



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



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



Complete blood count (cont.) RBC indices

MCV 90 ± 7 fl MCH 29 ± 2 pg MCHC 34 ± 2%

Aid in diagnosis and classification of anemias



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



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%



Complete blood count (cont.) White blood cell differential (cont.) Used to determine severity of infection, detect

allergic reactions, identify various leukemias



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



Complete blood count (cont.) Coagulation

Prothombin timeNormal: 9.5–11.8 s (control ±1 s)Therapeutic: 1.5–2.0 times normal control

Determined before anticoagulation therapy and monitored throughout therapy



Complete blood count (cont.) Coagulation

Activated partial thromboplastin time (APTT)Normal: 25–36 sTherapeutic: 1.5–2.5 times normal control

Evaluated clotting factors of the intrinsic pathway


Blood Chemistry IndicatorsBlood 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



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



Electrolytes (cont.) Sodium (cont.)

HyponatremiaCaused by vomiting, diarrhea, renal disorders,

diuretics, congestive heart failure Hypernatremia

Caused by inadequate fluid intake, diarrhea, diuretics



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



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



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



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



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



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



Liver function tests LDH 60–100 U/mL


Nutritional IndicatorsNutritional 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


Nutritional IndicatorsNutritional 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



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



Lipoproteins Total plasma cholesterol

Desired <200 mg/dL Borderline 200–239 mg/dL High 240 mg/dL

High-density lipoprotein HDL Desired >35



Lipoproteins Low-density lipoprotein (LDL)

Desired 130 mg/dL Borderline 130–159 mg/dL High 160 mg/dL

Triglycerides 160 mg/dL



Lipoproteins Lipid abnormalities are often familial Secondary causes

Diets high in saturated fat or cholesterol Excessive alcohol intake Estrogen supplements Smoking Sedentary lifestyle



Lipoproteins Cholesterol is decreased in malnutrition,

hyperthyroidism and chronic obstructive pulmonary disease


Drug Monitoring and ToxicologyDrug 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



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



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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