DR. HAILIN WUDR. YOSEPH FELEKE

Cardiac Injury

Cardiac Injury

(Creatine Kinase (CK), CK-MB, Myoglobin, Troponin I)

Creatine Kinase

Test Range and Collectionserum (CK)32–267 IU/L[0.53–4.45 mckat/L] (method-dependent)

Increased in: Myocardial infarction (MI), myocarditis, muscle trauma, rhabdomyolysis, muscular dystrophy, polymyositis, severe muscular exertion, malignant hyperthermia, hypothyroidism, cerebral infarction, surgery, Reye syndrome, tetanus, generalized convulsions, alcoholism, IM injections, DC countershock. Drugs: clofibrate, HMG-CoA reductase inhibitors.

During an MI, serum CK level rises rapidly (within 3–5 hours); elevation persists for 2–3 days post-MI.

Total CK is not specific enough for use in diagnosis of MI, but a normal total CK has a high negative predictive value. A more specific test is needed for diagnosis of MI or acute coronary syndrome (eg, CK-MB, now largely replaced by cardiac troponin I).

Creatine Kinase - MBTest Range and Collection

serum enzyme activity (CK-MB)<16 IU/L

Increased in: Myocardial infarction, cardiac trauma, certain muscular dystrophies, and polymyositis. Slight persistent elevation reported in a few patients on hemodialysis.

CK-MB is a relatively specific test for MI. It appears in serum approximately 4 hours after infarction, peaks at 12–24 hours, and declines over 48–72 hours. CK-MB mass concentration is a more sensitive marker of MI than CK-MB isoenzymes or total CK within 4–12 hours after infarction. Cardiac troponin I levels are useful in the late (after 48 hours) diagnosis of MI because, unlike CK-MB levels, they remain elevated for 5–7 days. Within 48 hours, sensitivity and specificity of troponin I are similar to CK-MB. Specificity of troponin I is higher than CK-MB in patients with skeletal muscle injury or renal failure, or postoperatively. Cardiac troponin I is therefore the preferred test.

Estimation of CK-MM and CK-BB is not clinically useful. Use total CK.

Myoglobin

A normal (negative) result is 0 - 85 nanograms per milliliter (ng/mL).

Myoglobin is the first enzyme that increases, but it returns to normal levels within the first 24 hours after the onset of symptoms.

When muscle is damaged, myoglobin is released into the bloodstream. The kidneys help remove myoglobin from the body into the urine. In large amounts, myoglobin can damage the kidneys. 

Troponin I

Test Range and Collection

serum ( Cardiac Troponin I: cTnI)<1.5 ng/mL (method- dependent)

Increased in: Myocardial infarction (sensitivity 50% at 4 hours, 97% at 6 hours; specificity 95%), cardiac trauma, cardiac surgery, myocardial damage following PTCA, and other cardiac interventions, nonischemic dilated cardiomyopathy, prolonged supraventricular tachycardia, acute dissection of the ascending aorta. Slight elevations noted in patients with recent aggravated unstable angina, muscular disorders, CNS disorders, HIV infection, chronic renal failure, cirrhosis, sepsis, lung diseases, and endocrine disorders.

Not increased in: Skeletal muscle disease (myopathy, myositis, dystrophy), external electrical cardioversion, noncardiac trauma or surgery, rhabdomyolysis, severe muscular exertion, chronic renal failure.

Lipid Panel

Lipid Panel (Total Cholesterol, Lipoproteins(LDL, HDL, VLDL), Triglycerdies (TG))

Cholesterol

Test Range and Collection Total, serum Desirable: <200 mg/dL Borderline: 200–239 mg/dL High risk: >240 mg/dL Fasting specimen is required for LDL-C determination.

HDL-C but total cholesterol can be measured with nonfasting specimen.

Cholesterol

Increased in: Primary disorders: polygenic hypercholesterolemia, familial hypercholesterolemia (deficiency of LDL receptors), familial combined hyperlipidemia, familial dysbetalipoproteinemia. Secondary disorders: hypothyroidism, uncontrolled diabetes mellitus, nephrotic syndrome, biliary obstruction, anorexia nervosa, hepatocellular carcinoma, Cushing syndrome, acute intermittent porphyria. Drugs: corticosteroids.

Decreased in: Severe liver disease (acute hepatitis, cirrhosis, malignancy), hyperthyroidism, severe acute or chronic illness, malnutrition, malabsorption (eg, HIV), extensive burns, familial (Gaucher disease, Tangier disease), abetalipoproteinemia, intestinal lymphangiectasia.

The recommended LDL-C intervention goals are <100 mg/dL for high-risk patients (eg, patients with CHD), <130 mg/dL for moderate-risk patients ( 2 risk factors), and <160 mg/dL for low-risk patients (no or 1 risk factor).

Triglycerides

Test Range and Collection serum (TG) Male: 40-160 mg/dL Female: 35-135 mg/dL Fasting specimen required.

Triglycerides

Increased in: Hypothyroidism, diabetes mellitus, nephrotic syndrome, chronic alcoholism (fatty liver), biliary tract obstruction, stress, familial lipoprotein lipase deficiency, familial dysbetalipoproteinemia, familial combined hyperlipidemia, obesity, the metabolic syndrome, viral hepatitis, cirrhosis, pancreatitis, chronic renal failure, gout, pregnancy, glycogen storage diseases types I, III, and VI, anorexia nervosa, dietary excess, and drugs.

Decreased in: Tangier disease ( -lipoprotein deficiency), hypo- and abetalipoproteinemia, malnutrition, malabsorption, parenchymal liver disease, hyperthyroidism, intestinal lymphangiectasia, and drugs.

Lipoproteins (LDL, HDL, VLDL)

Normal values:HDL: Male: >45 mg/dL Female: >55mg/dlLDL: Adult<130 mg/dL Children <110mg/dLVLDL 7-32 mg/dL. 

HDL densest and consists of mostly apoproteins and cholesterol

LDL carries most cholesterol in fasting state.VLDL mainly of triglycerides. With triglycerides < 400 mg/dL,

the ratio of cholesterol to triglycerides is 1:5 in VLDL.

Arterial Blood Gases

Arterial Blood Gases (PCO2, PO2, pH, HCO3¯)

pH: 7.35-7.45PCO2: 35-45 mm HgHCO3¯: 21-28 mEq/LPO2: 80-100 mm HgO2 saturation: 95-100%

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Arterial Blood Gases – PCO2

PCO2 is the measure of the partial pressure of CO2 in the blood. CO2 levels are very closely tied to respiratory function and can be easily influenced by respiratory rate.

Normal value: 35-45 mm HgCritical value: <20 or >60 mm Hg

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Arterial Blood Gases – PO2

PO2 is the measure of partial pressure of oxygen in the arterial blood. This pressure determines the capability of oxygen to diffuse across the alveolar membrane. PO2 will be low in patients with compromised pulmonary function such as pneumonia or COPD.

Normal value: 80-100 mm HgCritical value: <40 mm Hg

pH

Test Range and Collection whole blood Arterial: 7.35–7.45 Venous: 7.31–7.41 Heparinized syringe

Increased in: Respiratory alkalosis: hyperventilation (eg, anxiety), sepsis, liver disease, fever, early salicylate poisoning, and excessive artificial ventilation.

Metabolic alkalosis: Loss of gastric HCl (eg, vomiting), potassium depletion, excessive alkali administration (eg, bicarbonate, antacids), diuretics, volume depletion.

Decreased in: Respiratory acidosis: decreased alveolar ventilation (eg, COPD, respiratory depressants), neuromuscular diseases (eg, myasthenia gravis).

Metabolic acidosis (bicarbonate deficit): increased formation of acids ; decreased H+ excretion; increased acid intake and increased loss of alkaline body fluids.

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Arterial Blood Gases – HCO3¯

HCO3¯ is a measurement of renal function and not related to PCO2. As levels of HCO3¯ rise, so does blood pH. Bicarbonate has a direct relationship with pH and must be monitored in all patients with respiratory distress. Normally, the kidneys will reduce HCO3¯ uptake in cases of respiratory alkalosis to compensate. In the event of corresponding renal failure, this safety mechanism will not occur.

Normal value: 21-28 mEq/LCritical value: <15 or >40

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Arterial Blood Gases – O2 Sat

Oxygen saturation measures the amount of hemoglobin carrying oxygen in the arterial blood. O2 sat will go down as PO2 levels decrease. O2 sat can be easily done in a non-invasive fashion by pulse oximetry and is a reliable measure of pulmonary function in settings where drawing arterial blood is not possible.

Normal value: 95-100%Critical value: <75%

Electrolytes

Electrolytes (sodium, potassium, chloride, and CO2 levels)

SodiumTest Range and Collection

serum (Na+) 135–145 meq/L [mmol/L] Panic: <125 or >155 meq/L

Increased in: Dehydration (excessive sweating, severe vomiting, or diarrhea), polyuria (diabetes mellitus, diabetes insipidus), hyperaldosteronism, inadequate water intake (coma, hypothalamic disease), and drugs

Decreased in: CHF, cirrhosis, vomiting, diarrhea, exercise, excessive sweating (with replacement of water but not salt, eg, marathon running), salt-losing nephropathy, adrenal insufficiency, nephrotic syndrome, water intoxication, AIDS. and drugs.

Potassium

Test Range and Collection serum (K+) 3.5–5.0 meq/L [mmol/L] Panic: <3.0 or >6.0 meq/L

Increased in: Massive hemolysis, severe tissue damage, rhabdomyolysis, acidosis, dehydration, acute or chronic renal failure, Addison disease, renal tubular acidosis type IV (hyporeninemic hypoaldosteronism), hyperkalemic familial periodic paralysis, exercise (transient) and drugs.

Decreased in: Low potassium intake, prolonged vomiting or diarrhea, renal tubular acidosis types I and II, hyperaldosteronism, Cushing syndrome, osmotic diuresis (eg, hyperglycemia), alkalosis, familial periodic paralysis, trauma (transient), subarachnoid hemorrhage, genetic hypokalemic salt-losing tubulopathies such as Gitelman syndrome, and drugs

Chloride

Test Range and Collection serum (Cl–) 98–107 meq/L [mmol/L]

Increased in: Renal failure, nephrotic syndrome, renal tubular acidosis, dehydration, overtreatment with saline, hyperparathyroidism, diabetes insipidus, metabolic acidosis from diarrhea (loss of HCO3 –), respiratory alkalosis, hyperadrenocorticism, and drugs

Decreased in: Vomiting, diarrhea, gastrointestinal suction, renal failure combined with salt deprivation, over-treatment with diuretics, chronic respiratory acidosis, diabetic ketoacidosis, excessive sweating, SIADH, salt-losing nephropathy, acute intermittent porphyria, water intoxication, expansion of extracellular fluid volume, adrenal insufficiency, hyperaldosteronism, metabolic alkalosis, and drugs.

Carbon Dioxide

Test Range and Collection whole blood Arterial: 32–48 mm Hg (4.26–6.38 kPa) Heparinized syringe

Increased in: Respiratory acidosis: decreased alveolar ventilation (eg, COPD, respiratory depressants), neuromuscular diseases (eg, myasthenia gravis).

Decreased in: Respiratory alkalosis: hyperventilation (eg, anxiety), sepsis, liver disease, fever, early salicylate poisoning, and excessive artificial ventilation.