The Basic Metabolic Profile (BMP) is a group of tests that examine blood chemistry, that is, the components of blood excluding red and white blood cells and platelets.
The tests which make up a BMP may vary slightly between labs or institutions, but generally they will provide the physician with information about serum electrolytes, blood sugar and kidney function.
The tests described in this article include:
Sodium
Potassium
Chloride
Carbon Dioxide
Calcium
Glucose
Blood Urea Nitrogen (BUN)
Creatinine
Anion Gap
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Sodium
The normal range for serum sodium in the adult is 135 to 148 mEq/L.
Sodium (Na) aids in the regulation of the body's fluid balance, and along with potassium, maintains the electrical potential in the body that allows nerves to operate properly.
The fluids containing sodium are found almost entirely in extracellular (outside the cell) spaces, such as blood vessels. Sodium levels are maintained by the ingestion of sodium in food, and it is excreted through sweat, urine and feces.
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Common causes of decreased serum sodium (hyponatremia) include:
Decreased sodium intake / increased sodium loss
Excess water ingestion
Diarrhea
Vomiting
Administration of diuretics
Kidney disease
Addison’s disease
Edema and/or ascites.
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Common causes of increased sodium (hypernatremia) include:
Increased sodium intake / decreased sodium loss
Excessive free water loss, such as sweating, burns
Diabetes insipidus
Osmotic diuresis.
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Potassium
The normal range for serum potassium in the adult is 3.5 to 5.5 mEq/L.
Potassium (K), as opposed to sodium, is found almost entirely inside the cells of the body. Proper levels of potassium are critical to the normal function of muscles, including the heart.
Abnormal levels of potassium can cause severe irregularities in the heart's rhythm and ability to contract. Potassium is ingested in the diet and is excreted in urine.
Common causes of decreased potassium (hypokalemia) include:
Diuretic use without potassium replacement
Administration of IV fluids without potassium
Alcoholic cirrhosis
Diarrhea
Crohn's disease
Cushing's syndrome.
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Common causes of increased potassium (hyperkalemia) include:
Kidney disease or failure
Rapid administration of IV fluids containing potassium
Burns and crushing injuries, trauma
Myocardial infarction (heart attack)
Addison's disease.
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Chloride
The normal range for serum chloride in the adult is 95 to 105 mEq/L.
Chloride (Cl) works with sodium to maintain the balance of fluids in the body, and aids in the regulation of the acid / base balance. It is an anion (negatively charged particle) found mainly in extracellular spaces.
Chloride abnormalities can cause increased nervous system irritability, exaggerated reflex responses, decreased respiration, weakness, stupor and coma.
Alterations in chloride levels are unusual, but are found in association with other electrolyte imbalances.
Common causes of deceased chloride (hypochloremia) include:
Vomiting, diarrhea, or gastrointestinal suctioning
Administration of diuretics
Administration of IV fluids without electrolyte replacement.
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Common causes in increased chloride (hyperchloriemia) include:
Dehydration
Acid/base imbalances
Administration of medications containing chloride.
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Carbon Dioxide
The normal range for serum carbon dioxide in the adult is 23 to 30 mEq/L or 23 to 30 mmol/L.
Carbon dioxide (CO2) is an anion (negatively charged ion) that assists in acid / base balance and helps maintain the electrical neutrality of fluids both inside and outside cells.
In solution, carbon dioxide (CO2) combines with water (H2O) to form carbonic acid (H 2CO3). Higher levels of CO2 in the blood create an acidic condition (acidosis), and low levels create an alkaline condition (alkalosis).
Levels of CO2 are regulated by the kidneys and CO2 is expelled by the lungs during respiration.
Alterations in the concentration of this electrolyte do not occur in isolation; that is, abnormalities in CO2 are always related to a co-existing disease or condition.
Common causes of increased serum carbon dioxide (acidosis) include:
Diseases / conditions that decrease respiration
Burns
Congestive heart failure
Uncontrolled diabetes
Starvation
Kidney disease / failure
Diarrhea
Certain medications and poisons.
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Common causes of decreased serum carbon dioxide (alkalosis) include:
Diseases / conditions that increase respiration (hyperventilation)
Fluid losses from the GI tract (vomiting, suctioning)
Administration of diuretics
Administration of steroids
Cushing's disease
Salicylate intoxication
Excessive administration of medications containing bicarbonate.
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Calcium
The normal range for serum calcium in the adult is 9 to 10.5 mg/dL, or 2.25 to 2.75 mmol/L.
Calcium (Ca) is found primarily in the body in the form of bones and teeth; however, about 10% is found in the blood, in the form of a cation (positively charged ion) that plays an important role in the function of nerves and coagulation of blood.
When levels of serum calcium are low, the body produces hormones that remove calcium from bone to supplement serum calcium.
Because serum calcium plays an important role in nerve function, alterations in calcium levels can cause serious symptoms. These include decreased or exaggerated muscle tone, abnormal reflexes, severe gastrointestinal problems, such as nausea, vomiting, cramping and constipation, and disorders of the central nervous system, like lethargy, depression, convulsions and coma.
In extreme cases, pathological bone fractures can occur as a result of prolonged calcium loss.
Common causes of decreased serum calcium (hypocalcemia) include:
Diseases of the small intestine, interfering with calcium absorption
Excessive protein intake
Administration of blood with citrate
Hypoparathyroidism.
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Common causes of increased serum calcium (hypercalcemia) include:
Prolonged immobilization
Hyperparathyroidism
Diseases involving the breakdown of bone
Excessive ingestion of vitamin D
Kidney diseases / failure.
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Glucose
The normal range for serum glucose in the adult is 70 to 110 mg/dL.
Glucose (Glu) is a form of sugar that circulates in the blood to provide metabolic fuel for all body processes. Carbohydrates and sugars are ingested through food, broken down and absorbed in the small intestine, and are stored in the liver in the form of glucose.
The most common cause of abnormal blood sugar levels is Diabetes Mellitus, a disease in which serum glucose is consistently elevated as a result of decreased or absent insulin production, insulin resistance, or both.
The physical consequences of persistently elevated serum glucose / diabetes are many, and affect almost every body system.
The symptoms of decreased levels of serum glucose (hypoglycemia) can include sweating, anxiety, rapid pulse, and headache. If serum glucose drops to below 50 mg/dL, the patient may have loss of consciousness, and perhaps convulsions.
Common causes of increased serum glucose (hyperglycemia) include:
Diabetes Mellitus
Administration of certain steroids and hormones
Administration of total parenteral nutrition
Administration of diuretics
Diseases of the pancreas.
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Decreased serum glucose (hypoglycemia) is not common, but causes may include:
Administration of insulin or other hypoglycemic medication
Exercise
Exposure to severe cold
Malnutrition
Prolonged fever
Diseases of the pancreas
Decreases in pituitary or adrenocortical function.
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Blood Urea Nitrogen
The normal range for blood urea nitrogen in the adult is 4 to 22 mg/dL.
Blood urea nitrogen (BUN) is a waste product of protein metabolism. It is produced by the liver and excreted in the urine.
Abnormal elevations of BUN are most commonly caused by diseases of the kidney, prostate, and urinary tract, and the patient may have symptoms characteristic of fluid overload: decreased urine output, weight gain, edema, and distended neck veins. The skin may be yellowed and easily bruised, and the patient's mental state may be affected.
Decreased BUN is uncommon, but common causes may include:
Liver failure, inhibiting protein metabolism
Negative nitrogen balance (when protein breakdown exceeds protein intake)
Anorexia
Malnutrition
Prolonged IV therapy in patients receiving inadequate oral nutrition
Overhydration.
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Common causes of increased blood urea nitrogen (azotemia) include:
Kidney diseases / failure
Diseases decreasing the ability to excrete urine
Increased protein metabolism
Breakdown of muscle tissue (starvation, anorexia nervosa)
Infection
Trauma
Surgery
Gastrointestinal bleeding
Administration of corticosteroids
Administration of tetracyclines
Dehydration.
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Creatinine
The normal range for serum creatinine in the adult is 0.6 to 1.2 mg/dL. The ideal BUN:creatinine ratio is 20:1.
Creatinine (Cr) is a nitrogen-based waste product that is produced as a result of protein metabolism in muscle tissue. Creatinine is produced at a very steady rate and is not subject to rapid fluctuations. It is excreted by the kidneys.
Creatinine and BUN both measure kidney function, but in slightly different ways. It is clinically useful to evaluate the ratio of BUN to creatinine when conducting a diagnostic assessment.
Dehydration and protein breakdown can cause elevation in BUN, but may affect serum creatinine only slightly or not at all. However, if both BUN and serum creatinine are elevated, this strongly suggests the presence of primary kidney disease.
Common causes of increased serum creatinine include:
Kidney diseases / failure
Administration of diuretics, sulfonamides, chloramphenicol, ascorbic acid
Use of marijuana
Diet high in red meat.
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Decreased serum creatinine is rare, but has been associated with muscular dystrophy.
Anion Gap
The normal range for anion gap is 12 to 18 mmol/L; however, newer, more sensitive test equipment may have a reference range of -4 to 7 mmol/L.
The anion gap is a figure calculated by subtracting the number of anions (chloride and bicarbonate, the negatively charged electrolytes) from the cations (sodium and potassium, the positively charged electrolytes).
The remainder, the "gap," is composed of unmeasured electrolytes, organic ions, and plasma proteins.
An increased anion gap indicates that presence of an excess of the unmeasured anions which can occur when surplus hydrogen ions have been introduced into the body.
Surplus hydrogen ions can shift the pH (the measure of acid / base balance) of the body towards an acid state, or acidosis.
Common causes of an increased anion gap include condition or diseases that induce acidosis, such as:
Diabetic ketoacidosis
Lactic acidosis
Kidney failure associated with increased BUN
Various drug or chemical toxicities.
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Summary of Normal Ranges (Adult)
Sodium: 135 to 148 mEq/L
Potassium: 3.5 to 5.5 mEq/L
Chloride: 95 to 105 mEq/L
Carbon Dioxide: 23 to 30 mEq/L or 23 to 30 mmol/L
Calcium: 9 to 10.5 mg/dL, or 2.25 to 2.75 mmol/L
Glucose: 70 to 110 mg/dL
BUN: 4 to 22 mg/dL
Creatinine: 0.6 to 1.2 mg/dL
BUN / Creatinine ratio: 20:1
Anion Gap: 12 to 18 mmol/L (older equipment)
Anion Gap: -4 to 7 mmol/L (newer equipment)
McFarland M, Grant M. Nursing Implications of Laboratory Tests, 3rd ed. Delmar Publishers Inc
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