Ammonia

Common use

Specimen

Normal findings

Description

This procedure is contraindicated for

N/A

Indications

• Evaluate advanced liver disease or other disorders associated with altered serum ammonia levels
• Identify impending hepatic encephalopathy with known liver disease
• Monitor the effectiveness of treatment for hepatic encephalopathy, indicated by declining levels
• Monitor patients receiving hyperalimentation therapy

Potential diagnosis

Increased in

• Gastrointestinal hemorrhage (related to decreased blood volume, which prevents ammonia from reaching the liver to be metabolized)
• Genitourinary tract infection with distention and stasis (related to decreased renal excretion; levels accumulate in the blood)
• Hepatic coma (related to insufficient functioning liver cells to metabolize ammonia; levels accumulate in the blood)
• Inborn enzyme deficiency (evidenced by inability to metabolize ammonia)
• Liver failure, late cirrhosis (related to insufficient functioning liver cells to metabolize ammonia)
• Reye’s syndrome (related to insufficient functioning liver cells to metabolize ammonia)
• Total parenteral nutrition (related to ammonia generated from protein metabolism)

Decreased in

N/A

Critical findings

N/A

Interfering factors

• Drugs that may increase ammonia levels include asparaginase, chlorthiazide, chlorthalidone, fibrin hydrolysate, furosemide, hydroflumethiazide, isoniazid, levoglutamide, mercurial diuretics, oral resins, thiazides, and valproic acid.
• Drugs/organisms that may decrease ammonia levels include diphenhydramine, kanamycin, monoamine oxidase inhibitors, neomycin, tetracycline, and Lactobacillus acidophilus.
• Hemolysis falsely increases ammonia levels because intracellular ammonia levels are three times higher than plasma.
• Prompt and proper specimen processing, storage, and analysis are important to achieve accurate results. The specimen should be collected on ice; the collection tube should be filled completely and then kept tightly stoppered. Ammonia increases rapidly in the collected specimen, so analysis should be performed within 20 min of collection.

Nursing Implications and Procedure

Potential nursing problems

Pretest

• Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
• Patient Teaching: Inform the patient this test can assist with the evaluation of liver function related to processing protein waste. May be used to assist in diagnosis of Reye’s syndrome in infants.
• Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
• Obtain a history of the patient’s gastrointestinal, genitourinary, and hepatobiliary systems; symptoms; and results of previously performed laboratory tests and diagnostic and surgical procedures.
• Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
• Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
• Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
• Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

• Potential complications: N/A
• Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
• Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
• Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
• Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess the venipuncture site for bleeding or hematoma formation and secure the gauze with adhesive bandage.
• Promptly transport the specimen to the laboratory for processing and analysis. The tightly capped sample should be placed in an ice slurry immediately after collection. Information on the specimen label should be protected from water in the ice slurry by first placing the specimen in a protective plastic bag.

Post-Test

• Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.

• Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure. Recognize anxiety related to test results, and carefully observe the cirrhotic patient for the development of ascites, in which case fluid and electrolyte balance require strict attention. Dietary and fluid restrictions may be required; diuretics may be ordered. The patient should be frequently monitored for weight gain, intake and output, and abdominal girth. The alcoholic patient should be encouraged to avoid alcohol and also to seek appropriate counseling for substance abuse.

• Nutritional Considerations: Increased ammonia levels may be associated with liver disease. Dietary recommendations may be indicated, depending on the severity of the condition. A low-protein diet may be in order if the patient’s liver has lost the ability to process the end products of protein metabolism. A diet of soft foods may be required if esophageal varices have developed. Ammonia levels may be used to determine whether protein should be added to or reduced from the diet. Patients should be encouraged to eat simple carbohydrates and emulsified fats (as in homogenized milk or eggs) rather than complex carbohydrates (e.g., starch, fiber, and glycogen [animal carbohydrates]) and complex fats, which would require additional bile to emulsify them so that they could be used.
• Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

• Patient Education

  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
  • Answer any questions or address any concerns voiced by the patient or family.
  • Teach the patient that small frequent meals throughout the day can increase overall caloric intake and improve nutritional status.
  • Teach the patient that scratching can damage the skin and precipitate an infection.

• Expected Patient Outcomes

  • Knowledge
  • Discusses that adherence to eating several small meals can improve caloric intake
  • Associates compliance with taking lactalose with decreased blood ammonia level to help prevent hepatic encephalopathy
  • Skills
  • Modifies the diet and selects foods that are appropriate for the degree of liver disease (high protein and high carbohydrate can support nutrition until liver disease prohibits these food selections)
  • Accurately self-administers lactalose as prescribed to reduce absorption of ammonia
  • Attitude
  • Resolves to participate in counseling for alcohol abuse
  • Follows the recommendations of the physician and family members in supporting positive health decisions

Related Monographs

• Related tests include ALT, albumin, analgesic, anti-inflammatory, and antipyretic drugs (acetaminophen and acetylsalicylic acid), anion gap, AST, bilirubin, biopsy liver, blood gases, BUN, blood calcium, CT biliary tract and liver, CT pelvis, cystometry, cystoscopy, EGD, electrolytes, GI blood loss scan, glucose, IVP, MRI pelvis, ketones, lactic acid, Meckle’s scan, osmolality, protein, PT/INR, uric acid, and US pelvis.
• See the Gastrointestinal, Genitourinary, and Hepatobiliary systems tables at the end of the book for related tests by body system.