Ammonia

General

Synonym/Acronym:
NH3.

Rationale
To assist in diagnosing liver disease such as hepatitis and cirrhosis and evaluating the effectiveness of treatment modalities. Also used to assist in diagnosing infant Reye syndrome.

Patient Preparation
There are no food, fluid, or medication restrictions unless by medical direction. Smoking should be restricted for 8 hr prior to the study.

Normal Findings
Method: Enzymatic.

AgeConventional and SI Units
Newborn–14 dLess than 100 micromol/L
15 d–6 yrLess than 68 micromol/L
AdultLess than 73 micromol/L

Critical Findings and Potential Interventions
N/A

Overview

(Study type: Blood collected in completely filled lavender- [EDTA] or green-top [Na or Li heparin] tube; related body system: Digestive system.) Specimen should be transported tightly capped and in an ice slurry.



Blood ammonia (NH3) comes from two sources: deamination of amino acids during protein metabolism and degradation of proteins by colon bacteria. The liver converts ammonia in the portal blood to urea, which is excreted by the kidneys. When liver function is severely compromised, especially in situations in which decreased hepatocellular function is combined with impaired portal blood flow, ammonia levels rise. Inherited enzyme defects that prevent the breakdown of ammonia or conditions that affect the ability of the kidneys to excrete ammonia can also result in increased blood levels. Ammonia is potentially toxic to the central nervous system and may result in encephalopathy or coma if toxic levels are reached.

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.

Interfering Factors

  • Drugs and other substances that may increase ammonia levels include acetazolamide, ammonium chloride, ethyl alcohol, fibrin hydrolysate, furosemide, isoniazid, rifampin, thiazides, and valproic acid.
  • Drugs/organisms and other substances that may decrease ammonia levels include diphenhydramine, kanamycin, lactulose, levodopa, neomycin, tetracycline, and Lactobacillus acidophilus.
  • Cigarette smoking increases ammonia levels.
  • 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.

Potential Medical Diagnosis: Clinical Significance of Results

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 syndrome (related to insufficient functioning liver cells to metabolize ammonia)
  • Total parenteral nutrition (related to ammonia generated from protein metabolism)

Decreased in

N/A

Nursing Implications, Nursing Process, Clinical Judgement

Potential Problems: Assessment & Nursing Diagnosis/Analysis

ProblemsSigns and Symptoms
Confusion (related to an alteration in fluid and electrolytes, hepatic disease and encephalopathy, substance use disorder [alcohol], hepatic metabolic insufficiency) Disorganized thinking; restlessness; irritability; altered concentration and attention span; changeable mental function over the day; hallucinations; inability to follow directions; disoriented to person, place, time, and purpose; inappropriate affect
Fatigue (related to deficient metabolic energy production associated with faulty metabolism and storage of nutrients, decreased nutritional intake, decreased nutrient utilization) Weakness, lethargy, complaints of tiredness, inability to perform activities of daily living, irritability, agitation, falls asleep during normal waking hours, complains of lack of energy

Before the Study: Planning and Implementation


Teaching the Patient What to Expect

  • Discuss how this test can assist with the evaluation of liver function related to processing protein waste and that a blood sample is needed for the test.
  • Advise parents that this test may be used to assist in diagnosis of Reye syndrome in infants.

After the Study: Implementation & Evaluation Potential Nursing Actions


Avoiding Complications

  • Administer ordered diuretics. Monitor frequently for weight gain. Monitor and trend intake and output. Monitor and trend abdominal girth. Enforce dietary and fluid restrictions.
  • Symptoms related to poor skin integrity include jaundiced skin and sclera, dry skin, itching skin, damage to skin associated with scratching.
  • Interventions/actions related to skin integrity include the following: Application of lotion to keep the skin moisturized. Discourage scratching and apply mittens if the patient is unable to follow direction. Administer ordered antihistamines to provide relief and comfort. Advise avoiding alkaline soaps.

Treatment Considerations

  • Bleeding can be a concern. Symptoms related to bleeding include altered level of consciousness, hypotension, increased heart rate, decreased Hgb and Hct, capillary refill greater than 3 sec, cool extremities.
  • Interventions/actions related to bleeding include the following: Increase frequency of vital sign assessment, noting trends and variances in results. Administer blood or blood products as ordered. Administer stool softeners as needed to decrease constipation risk. Encourage the intake of foods rich in vitamin K+. Avoid foods that may irritate the esophagus.

Safety Considerations

  • Follow established organizational fall prevention protocols, identify previous fall history and frequency.
  • Interventions/actions related to fall risk include the following: Assess risk on admission, transfer, post-fall, and change of condition. Monitor for unsteady gait and decreased ability to complete activities of daily living independently. Assess for decreased visual acuity, or hearing, fatigue, weakness, or difficulty following instructions. Evaluate for improper assistive device use, altered color perception, changed center of gravity, or delayed response and reaction times. Review medications to identify any pharmacological contributors to fall risk. Monitor glucose and ammonia levels as potential contributors to confusion.
  • Interventions/actions related to environmental fall risk factors include the following: move frequently used items close to the bed to decrease desire to get up. Move the patient closer to the nurses station for easier observation. Place the bed in the lowest possible position and raise side rails judiciously as the situation requires. Ensure the room is well lit to prevent tripping. Encourage the use of well-fitting shoes with nonskid soles. Answer call lights timely to decrease risk of getting up. Encourage the use of eyeglasses and hearing aids. Enlist the support of reliable family members as partners in preventing falls.

Confusion

  • Interventions/actions related to confusion include the following: Treat the medical condition associated with the confusion. Correlate confusion with the need to reverse altered electrolytes, including ammonia levels. Evaluate medications to identify those that may be contributing to confusion. Prevent falls and injury through use of postural support, bed alarm, or the appropriate use of restraints. Consider pharmacological interventions to decrease confusion and injury through fall risk. Track accurate intake and output to assess fluid status. Identify last alcohol use as this may contribute to confusion. Assess for symptoms of hepatic encephalopathy, including confusion, sleep disturbances, and incoherence. Administer ordered lactulose.

Fatigue

  • Obtain a history of normal activity level for baseline comparison.
  • Interventions/actions related to fatigue include the following: Schedule planned activities away from meal times to prevent exhaustion from affecting nutritional intake. Encourage small, frequent meals. Pace activities to encourage periods of rest and conserve oxygen, decreasing metabolic demands. Assess activity tolerance and increase as tolerated. Teach how to manage energy effectively. Ensure that frequently used items are kept within reach.

Nutritional Considerations

  • Dietary recommendations will vary depending on patient condition and disease severity. Soft foods may be recommended if esophageal varices develop or limitations on salt intake if ascites develop. Patients may be encouraged to eat a well-balanced diet that includes foods high in fiber.
  • Symptoms related to inadequate nutrition include known inadequate caloric intake; weight loss; muscle wasting in arms and legs; stool that is pale or gray colored; skin that is flaky with loss of elasticity.
  • Interventions/actions related to inadequate nutrition include the following: Document food intake; use a calorie count and food diary to identify deficits and barriers to eating. Discourage continued alcohol use as it is a barrier to adequate protein. Consider a dietary consult with assessment of cultural food selections. Teach the patient that small, frequent meals throughout the day can increase overall caloric intake and improve nutritional status. Monitor daily weight.

Clinical Judgement

  • Consider ways to convince the patient to acknowledge and overcome barriers toward substance use disorder (alcohol) with the goal of long-term healthy living.

Followup Evaluation and Desired Outcomes

  • Accepts the necessity of accurate self-administration of lactulose to reduce absorption of ammonia; decreased blood ammonia level will help prevent hepatic encephalopathy.
  • Acknowledges the importance of making food selections that are appropriate for the degree of liver disease (high protein and high carbohydrate can support nutrition until liver disease prohibits these food selections).
  • Understands that scratching can damage the skin and precipitate an infection.