Before Administering the Test
Assess if the patient:• Performed strenuous exercise during the two days prior to the test
• Has taken:
• Blood creatinine level test: Diuretics, Proloprim, Trimpex, Aldomet, Tagamet, ascorbic acid, cephalosporin, or Mefoxin
• Creatinine clearance test: Dilantin, cephalosporin, captopril, ascorbic acid, Garamycin, Tagamet, Proloprim, Trimpex, Cardioquin, Quinaglute, quinine, Quinidex, amphotericin B, or procainamide
• BUN to creatinine ratio test: Tetracycline or Tagamet
• Ingested protein for one day prior to the test
• Drunk coffee or tea before the creatinine clearance test, since these increase urine production
How the Test Is Performed
A sample of blood is taken from the patient’s vein. The patient will experience a tight feeling when the tourni- quet is tightened, a pinch or nothing at all when the needle is inserted into the vein, and pressure when a gauze pad is pressed against the insertion site to stop bleeding. It can take up to 10 minutes for bleeding to stop if the patient is taking anticoagulants (aspirin, coumadin). A small bruise might appear at the insertion site, which could become swollen following this test. This is called phlebitis. Applying a warm compress several times a day will reduce the swelling.
See 24-Hour Urine Collection.
Teach the Patient
Explain why the sample is taken. The patient should avoid:
• Strenuous exercise for two days prior to the test
• Ingesting protein for one day prior to the test
• Drinking coffee and tea before the creatinine clearance test, since these increase urine production.
Explain that the healthcare provider may ask the patient to refrain from taking these medications prior to the test:
• Blood creatinine level test: Diuretics, Proloprim, Trimpex, Aldomet, Tagamet, ascorbic acid, cephalosporin or Mefoxin
• Creatinine clearance test: Dilantin, cephalosporin, captopril, ascorbic acid, Garamycin, Tagamet, Proloprim, Trimpex, Cardioquin, Quinaglute, quinine, Quinidex, amphotericin B or procainamide
• BUN to creatinine ratio test: Tetracycline or Tagamet
Understanding the Test Results
The creatinine blood level test and creatinine clearance test results are available quickly. The laboratory deter- mines normal values based on calibration of testing equipment with a control test. Test results are reported as high, normal, or low based on the laboratory’s control test.
• Normal test results:
• Blood creatinine level:
■ Men: 0.6 to 1.2 mg/dL
■ Women: 0.5 to 1.1 mg/dL
■ 13 years old to 19 years old: 0.5 to 1.0 mg/dL
■ 6 months to 12 years old: 0.3 to 0.7 mg/dL
■ Newborns: 0.3 to 1.2 mg/dL
• Creatinine clearance:
■ Men: 90 to 140 mL/min.
■ Women: 87 to 107 mL/min
• BUN to creatinine ratio:
■ Over 11 months of age: 10:1 to 20:1
■ Under 12 months of age: 30:1 or less
Higher levels may indicate: (creatinine blood level) kidney disorder, shock, kidney stones, dehydration, rhab- domyolysis, acromegaly, gigantism, polymyositis, muscular dystrophy, urinary tract blockage, or cancer; (crea- tinine clearance) muscle injury, pregnancy, hypothyroidism, burns, strenuous exercise, or carbon monoxide poisoning; (BUN to creatinine ratio) dehydration, kidney stone, shock, or acute kidney failure.
Lower levels may indicate: (blood creatinine levels) protein deficient diet, decreased muscle mass, pregnancy, or liver disease; (creatinine clearance) cirrhosis, dehydration, infection, kidney disorder, urinary tract blockage, or reduced blood to the kidneys; (BUN to creatinine ratio) protein deficient diet, cirrhosis, rhabdomy- olysis, SIADH, cancer, or pregnancy.
Solved Problems
Renal Function Tests
12.1 What metabolic waste can be reused by the body?
Metabolic waste such as sodium, potassium, and phosphorus can be reused by the body and are returned to the blood by the kidneys.
12.2 How is renal function measured?
Renal function is measured in percentages. A person with two healthy kidneys has 100% renal function.
A person with one healthy kidney and one kidney in total renal failure is said to have 50% renal function.
12.3 At what level of renal function will a patient be placed on dialysis?
Dialysis is typically ordered for a patient with less than 15% renal function.
12.4 When does renal failure occur?
Renal failure occurs when the glomerulus no longer filters waste from the blood.
12.5 What type of renal failure occurs as a result of diabetes and high blood pressure?
Chronic kidney disease.
12.6 What causes acute renal failure?
This can occur suddenly in response to illness, medications, accidents, and poisons.
Blood Urea Nitrogen
12.7 What does the blood urea nitrogen test measure?
The blood urea nitrogen (BUN) test measures the level of nitrogen in the blood.
12.8 What is the source of the nitrogen in blood?
Urea.
12.9 What is the source of urea?
Ammonia is formed when bacteria in the intestines break down protein. Ammonia is then converted into urea by the liver.
12.10 Why is the blood urea nitrogen test ordered?
The test screens for kidney function and dehydration. The test assesses for the treatment for kidney disease and kidney dialysis.
12.11 What must be considered before administering the blood urea nitrogen test?
Assess:
• If the patient has eaten meat or protein prior to the administration of the test
• If the patient has taken Fungizone, Garamycin, Nebcin, chloromycetin, nafcillin, Kantrex, tetracycline, or diuretics
• The patient’s age, since BUN levels increase with age.
CHAPTER 12 Renal Function Tests 134
12.12 What might a high blood urea nitrogen test value mean?
High BUN values may indicate kidney disease, kidney stones, Addison’s disease, kidney tumor, burns, heart failure, GI bleeding, dehydration, or a high protein diet.
12.13 What might a high BUN to creatinine ratio value mean?
A high BUN to creatinine ratio may indicate respiratory tract bleeding, GI tract bleeding, shock, kidney failure, urinary tract blockage, or dehydration.
12.14 What might a low blood urea nitrogen test value mean?
Low BUN values may indicate malnutrition, liver damage, overhydration, or a low protein diet.
12.15 What might a low BUN to creatinine ratio value mean?
A low BUN to creatinine ratio may indicate rhabdomyolysis, cirrhosis, SIADH, or muscle injury.
12.16 What might a high level of BUN and creatinine level mean?
Both BUN and creatinine levels are high when there is blockage of urine flow.
Creatinine and Creatinine Clearance
12.17 What is creatine?Creatine phosphate provides energy to skeletal muscles. After seven seconds of intense effort, creatine phosphate converts to creatine.
12.18 What is the difference between creatine and creatinine?
Creatine is metabolized into creatinine and is carried in blood to the kidneys for filtering and excreted in urine.
12.19 What happens if kidneys malfunction?
If kidneys are malfunctioning, creatinine levels in the blood increase and creatinine levels in urine decrease.
12.20 What does the creatinine clearance test measure?
The creatinine clearance test measures creatinine in a 24-hour urine sample and measures the level of creatinine in blood.
12.21 What does the BUN:creatinine test measure?
The BUN:creatinine test compares the results of the blood urea test with the blood creatinine level test to assess for dehydration.
12.22 How is the fetal kidney function assessed?
Fetal kidney function is assessed by testing the level of creatinine in amniotic fluid.
12.23 What must be assessed before the creatinine tests are administered?
Assess if the patient:
• Performed strenuous exercise two days prior to the test
• Has taken:
• Blood creatinine Level Test: Diuretics, Proloprim, Trimpex, Aldomet, Tagamet, ascorbic acid, cephalosporin, or Mefoxin
• Creatinine clearance test: Dilantin, cephalosporin, Captopril, ascorbic acid, Garamycin, Tagamet, Proloprim, Trimpex, Cardioquin, Quinaglute, quinine, Quinidex, amphotericin B or procainamide
• BUN to creatinine ratio test: Tetracycline or Tagamet
• Ingested protein for one day prior to the test
• Drunk coffee or tea before the creatinine clearance test, since these increase urine production
CHAPTER 12 Renal Function Tests 135
12.24 What might a high level of creatinine indicate?
A high level of creatinine may indicate kidney disorder, kidney stones, dehydration, shock, rhabdomyolysis, acromegaly, gigantism, polymyositis, muscular dystrophy, a urinary tract blockage, or cancer.
12.25 What might a high level result of the creatinine clearance test indicate?
A high level result of the creatinine clearance test may indicate muscle injury, pregnancy, hypothyroidism, burns, strenuous exercise, or carbon monoxide poisoning.
CHAPTER 12 Renal Function Tests 136
137
C H A P T E R 1 3
Pancreas and Lipid Metabolism Tests
13.1 Definition
Healthcare providers order lipid metabolism tests to determine the level of lipids in the patient’s blood stream and pancreatic tests to determine pancreatic function. The pancreas produces insulin and glucagon along with digestive enzymes that are used by the small intestine to break down carbohydrates, protein, and fat. Lipidsare compounds used to store energy, develop cell membranes, and are elements of vitamins and hormones. Lipids combine with pro- tein to form lipoprotein. Common lipoproteins in the body are cholesterol and triglycerides. Cholesterol is released into the bloodstream mostly by the liver and other organs, although some cholesterol is ingested in food. Two types of cholesterol are high-density lipoprotein (HDL)and low-density lipoprotein (LDL). There is a balance between LDL and HDL. LDL is distributed to cells throughout the body by the bloodstream. Excess LDL is removed by HDL from the blood and transported to the liver, where LDL is metabolized into bile acids and excreted from the body.
An imbalance occurs when too much LDL is in the blood, leading to accumulation of LDL on the artery walls.
This causes a narrowing of the arteries and leads to a blockage. The healthcare provider is likely to order a lipase test along with the amylase test. Lipaseis an enzyme that is produced only by the pancreas. The amylase test may also be performed with the creatinine test to help the healthcare provider diagnose pancreatitis.
13.2 Amylase
The amylase test measures the amount of amylase in blood. Amylaseis an enzyme that breaks down starch into sugar. Amylase is produced by salivary glands and the pancreas. There is normally a low level of amylase in blood unless the salivary glands or pancreas is blocked or damaged.
Why the Test Is Performed
The test screens for pancreatic disease, pancreatitis, and inflammation of the salivary glands. It also assesses the treatments for pancreatic and salivary glands disease.
Before Administering the Test
Assess if the patient:• Refrained from eating and drinking anything except water 2 hours before the test
• Drank alcohol 24 hours before the test
• Took codeine, morphine, diuretics, coumadin, indocin, aspirin, or birth control pills, since these can affect the test results
• Has chronic kidney disease, since this can cause high levels of amylase
• Has liver or pancreas damage, since this can affect the test result
CHAPTER 13 Pancreas and Lipid Metabolism Tests 138
How the Test Is Performed
• Refrain from eating or drinking anything except water for 2 hours before the test
• Avoid drinking alcohol for 24 hours before the test
A sample of blood is taken from the patient’s vein. The patient will experience a tight feeling when the tourni- quet is tightened, a pinch or nothing at all when the needle is inserted into the vein, and pressure when a gauze pad is pressed against the insertion site to stop bleeding. It can take up to 10 minutes for bleeding to stop if the patient is taking anticoagulants (aspirin, coumadin). A small bruise might appear at the insertion site, which could become swollen following this test. This is called phlebitis. Applying a warm compress several times a day will reduce the swelling.
Teach the Patient
Explain why the blood sample is taken, the function of amylase, and the meaning of abnormal values. Explain that the patient must refrain from eating or drinking anything except water for 2 hours before the test and avoid drinking alcohol for 24 hours before the test, and that the patient should tell the healthcare provider if he or she is taking codeine, morphine diuretics, coumadin, indocin, aspirin, or birth control pills, since these can affect the test results.
Understanding the Test Results
Test results are available within 3 days. The laboratory determines normal values based on calibration of test- ing equipment with a control test. Test results are reported as high, normal, or low based on the laboratory’s con- trol test. Generally the normal range is: 60 to 180 U/L. High values are normal for older adults and pregnant women. The patient may have chronic pancreatitis, even if there is a low amylase level. Children have very little amylase until they reach their first birthday, and then their amylase is at the normal adult level.
A high level may indicate pancreatitis, pancreatic cancer, mumps, bowel infarction, inflammation of the salivary glands, cystic fibrosis, diabetic ketoacidosis, gallstones, stomach ulcer, macroamylasemia, or ectopic pregnancy.
A low level may indicate preeclampsia, advanced cystic fibrosis, severe liver disease, or macroamylasemia.
13.3 Lipase
The lipase test measures the level of lipase in blood. Lipaseis an enzyme in the pancreas. Levels of lipase in the blood increase when the pancreatic duct is blocked or there is damage to the pancreas. The lipase test does not diagnose pancreatic disorder. A high level of lipase in blood requires additional testing. The healthcare provider may order the amylase test at the same time as the lipase test.
Why the Test Is Performed
The test screens for pancreatic disease, pancreatitis, and cystic fibrosis. The test also assesses treatment for pan- creatitis and cystic fibrosis.
Before Administering the Test
Assess if the patient has:• Eaten or drunk anything except water 12 hours before the test is administered
• High cholesterol, varicose veins, kidney disease, diabetes, or high blood pressure
• Taken narcotics, anticoagulants, or cholinergics
How the Test Is Performed
• Avoid eating or drinking anything except water 12 hours before the test is administered.