Ammonia

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–2 yrLess than 80 micromol/L
3–17 yrLess than 35 micromol/L
AdultLess than 50 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

Factors that may alter the results of the study

  • 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 Nursing Problems Assessment and Nursing Diagnosis

ProblemsSigns and Symptoms
Bleeding (related to altered levels of clotting factors, portal hypertension, esophageal bleeding)Altered level of consciousness, hypotension, increased heart rate, decreased Hgb and Hct, capillary refill greater than 3 sec, cool extremities
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
Fall, risk (related to impaired mobility, assistive device use, acute or chronic disease process, dizziness, confusion, history of previous falls)Unsteady gait; decreased ability to complete activities of daily living independently, decreased visual acuity, or hearing; fatigue; weakness; difficulty following instructions; improper assistive device use; altered color perception; changed center of gravity; delayed response and reaction times
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 while during normal waking hours, complains of lack of energy
Nutrition (inadequate—related to excess alcohol intake, poor eating habits, altered liver function)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
Skin (related to jaundice and elevated bilirubin levels, excessive scratching)Jaundiced skin and sclera, dry skin, itching skin, damage to skin associated with scratching

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.
  • Advise parents that this test may be used to assist in diagnosis of Reye syndrome in infants.
  • Explain that a blood sample is needed for the test.

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.

Skin

  • Apply lotion to keep the skin moisturized.
  • Advise avoiding alkaline soaps.
  • Discourage scratching and apply mittens if the patient is unable to follow direction to avoid scratching.
  • Administer ordered antihistamines to provide relief and comfort.

Treatment Considerations

Bleeding

  • 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 intake of foods rich in vitamin K and avoidance of foods that may irritate the esophagus.

Safety Considerations

Confusion

  • 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.
  • Determine last alcohol use as this may contribute to confusion.
  • Assess for symptoms of hepatic encephalopathy including confusion, sleep disturbances, and incoherence.
  • Administer ordered lactulose.

Fall, Risk

  • Assess fall risk on admission, transfer, post-fall, and change of condition.
  • Follow established organizational fall prevention protocols.
  • Identify previous fall history and frequency.
  • Assess for disease-related symptoms such as orthostatic hypotension, urinary incontinence
  • Move the patient closer to the nurses station for easier observation.
  • Enlist the support of reliable family members as partners in preventing falls.
  • Move frequently used items close to the bed to decrease desire to get up.
  • Answer call lights timely to decrease risk of getting up.
  • Place the bed in the lowest possible position.
  • Raise side rails judiciously as the situation requires.
  • Encourage the use of well-fitting shoes with nonskid soles.
  • Ensure the room is well lit to prevent tripping.
  • Review medications to identify any pharmacological contributors to fall risk.
  • Encourage the use of eyeglasses and hearing aids.

Fatigue

  • Schedule planned activities away from meal times to prevent exhaustion from affecting nutritional intake.
  • Pace activities to encourage periods of rest, conserving oxygen and decreasing metabolic demands.
  • Obtain a history of normal activity level for baseline comparison.
  • Assess activity tolerance and increase as tolerated.
  • Teach how to manage energy effectively.
  • Encourage small, frequent meals.
  • Ensure that frequently used items are kept within reach.
  • Administer ordered acid suppression medications, antiemetics, and antidiarrheals.

Nutritional Considerations

  • Encourage eating a well-balanced diet that includes foods high in fiber.
  • Note that dietary recommendations will vary depending on the condition and its severity. For example, soft foods may be recommended if esophageal varices develop or limitations on salt intake if ascites develop.
  • Document food intake with potential calorie count in a food diary to better identify nutrition deficits.
  • Discourage continued alcohol use as it is a barrier to adequate protein nutrition.
  • Evaluate barriers to eating, and 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.
  • Monitor glucose and ammonia levels as potential contributors to confusion.

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.

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