Diagnosis of Cystic Fibrosis
Diagnostic Test list for Cystic Fibrosis:
The list of medical tests
mentioned in various sources as
used in the diagnosis of Cystic Fibrosis
includes:
Cystic Fibrosis Diagnosis: Book Excerpts
Tests and diagnosis discussion for Cystic Fibrosis:
NHLBI, Facts About Cystic Fibrosis: NHLBI (Excerpt)
The
most common test for CF is called the sweat test. It measures the amount of salt
(sodium chloride) in the sweat. In this test, an area of the skin (usually the
forearm) is made to sweat by using a chemical called pilocarpine and applying a
mild electric current. To collect the sweat, the area is covered with a gauze
pad or filter paper and wrapped in plastic. After 30 to 40 minutes, the plastic
is removed, and the sweat collected in the pad or paper is analyzed. Higher than
normal amounts of sodium and chloride suggest that the person has cystic
fibrosis.
The sweat test may not work well in newborns because they do not produce
enough sweat. In that case, another type of test, such as the immunoreactive
trypsinogen test (IRT), may be used. In the IRT test, blood drawn 2 to 3 days
after birth is analyzed for a specific protein called trypsinogen. Positive IRT
tests must be confirmed by sweat and other tests.
Also, a small percentage of people with CF have normal sweat chloride levels.
They can only be diagnosed by chemical tests for the presence of the mutated
gene. Some of the other tests that can assist in the diagnosis of CF are chest
x-rays, lung function tests, and sputum (phlegm) cultures. Stool examinations
can help identify the digestive abnormalities that are typical of CF. (Source: excerpt from NHLBI, Facts About Cystic Fibrosis: NHLBI)
NHLBI, Facts About Cystic Fibrosis: NHLBI (Excerpt)
Finding out whether a baby is likely to have CF is possible
using prenatal genetic tests. However, the tests cannot detect all of the CF
gene mutations. Also, because these tests are very expensive and have certain
risks to the mother, they are not used for all pregnant women. If there is
another child with CF in the family, the expectant mother may request a prenatal
test to see if the fetus has CF genes from both parents, is a carrier for one
gene, or is altogether free of the CF genes.
There are two special prenatal tests that can be done--either an
amniocentesis or chorionic villus biopsy will be performed. In amniocentesis,
cells from the fluid surrounding the baby in the mother's womb (called the
amniotic fluid) are tested to see if the CF genes common to the parents are
present. In chorionic villus biopsy, cells from the tissue that will eventually
form the placenta are tested for the CF gene. (Source: excerpt from NHLBI, Facts About Cystic Fibrosis: NHLBI)
Diagnosis of Cystic Fibrosis: medical news summaries:
The following medical news items
are relevant to diagnosis and misdiagnosis issues for Cystic Fibrosis:
Diagnostic Tests for Cystic Fibrosis: Online Medical Books
16 MEDICAL BOOKS ONLINE!
Review excerpts from medical books online, free, without registration,
for more information about diagnostis of Cystic Fibrosis.
Cystic fibrosis:
Diagnosis
(Professional Guide to Diseases (Eighth Edition))
Confirming diagnosis
The Cystic Fibrosis Foundation has developed certain criteria for a definitive diagnosis: Two sweat tests using a pilocarpine solution (a sweat inducer) and either obstructive pulmonary disease, confirmed pancreatic insufficiency or failure to thrive, and a family history of cystic fibrosis.
The following test results may support the diagnosis:
❑ Chest X-rays indicate early signs of obstructive lung disease.
❑ Stool specimen analysis indicates the absence of trypsin, suggesting pancreatic insufficiency.
❑ Deoxyribonucleic acid testing can now locate the presence of the Delta F 508 deletion (found in about 70% of cystic fibrosis patients, although the disease can cause more than 100 other mutations). It allows prenatal diagnosis in families with a previously affected child.
❑ Pulmonary function tests reveal decreased vital capacity, elevated residual volume due to air entrapments, and decreased forced expiratory volume in 1 second. This test is used if pulmonary exacerbation already exists.
❑ Liver enzyme tests may reveal hepatic insufficiency.
❑ Sputum culture reveals organisms that cystic fibrosis patients typically and chronically colonize, such as Staphylococcus and Pseudomonas.
❑ Serum albumin measurement helps assess nutritional status.
❑ Electrolyte analysis assesses hydration status.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Diseases (Eighth Edition), 2005
Pancreatic cancer:
Diagnosis
(Professional Guide to Diseases (Eighth Edition))
Definitive diagnosis requires a laparotomy with a biopsy.
Other tests used to detect pancreatic cancer include:
❑ultrasound of the abdomen — can identify a mass but not its histology
❑computed tomography scan of the abdomen — similar to ultrasound but shows greater detail
❑ angiography — shows vascular supply of tumor
❑ endoscopic retrograde cholangiopancreatography — allows visualization, instillation of contrast medium, and specimen biopsy
❑ magnetic resonance imaging of the abdomen — shows tumor size and location in great detail.
Laboratory tests supporting this diagnosis include serum bilirubin (increased); serum amylase and serum lipase (sometimes elevated); prothrombin time (prolonged); aspartate aminotransferase and alanine aminotransferase (elevations indicate necrosis of liver cells); alkaline phosphatase (marked elevation occurs with biliary obstruction); plasma insulin immunoassay (shows measurable serum insulin in the presence of islet cell tumors) (see Islet cell tumors); hemoglobin (Hb) and hematocrit (HCT) (may show mild anemia); fasting blood glucose (may indicate hypoglycemia or hyperglycemia); and stools (occult blood may signal ulceration in GI tract or ampulla of Vater).
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Diseases (Eighth Edition), 2005
Cirrhosis and fibrosis:
Diagnosis
(Professional Guide to Diseases (Eighth Edition))
CONFIRMING DIAGNOSIS Liver biopsy, the definitive test for cirrhosis, detects destruction and fibrosis of hepatic tissue.
Liver scan shows abnormal thickening and a liver mass. Cholecystography and cholangiography visualize the gallbladder and the biliary duct system, respectively; splenoportal venography visualizes the portal venous system. Percutaneous trans-hepatic cholangiography differentiates extrahepatic from intrahepatic obstructive jaundice and discloses hepatic pathology and the presence of gallstones.
Laboratory findings that are characteristic of cirrhosis include:
❑ decreased white blood cell count, hemoglobin level and hematocrit, albumin, serum electrolyte levels (sodium, potassium, chloride, and magnesium), and cholinesterase
❑ elevated levels of globulin, serum ammonia, total bilirubin, alkaline phosphatase, serum aspartate aminotransferase, serum alanine aminotransferase, and lactate dehydrogenase and increased thymol turbidity
❑ anemia, neutropenia, and thrombocytopenia, characterized by prolonged prothrombin and partial thromboplastin times
❑ deficiencies of folic acid, iron, and vitamins A, B12, C, and K.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Diseases (Eighth Edition), 2005
Pancreatitis:
Diagnosis
(Handbook of Diseases)
Clinical presentation and combined laboratory and radiographic findings form the basis for diagnosis. A thorough patient history (especially for alcoholism) and physical examination are the first steps in diagnosis; however, the retroperitoneal position of the pancreas makes physical assessment difficult.
Dramatically elevated serum amylase levels —in many patients over 500 U/L — confirm pancreatitis and rule out perforated peptic ulcer, acute cholecystitis, appendicitis, and bowel infarction or obstruction. Persistent elevation of serum amylase levels may indicate pancreatic necrosis, pseudocyst, or abscess.
Similarly, dramatically elevated amylase levels are also found in urine, ascites, or pleural fluid. Characteristically, amylase levels return to normal within 48 hours after the onset of pancreatitis, despite continuing symptoms. Laboratory values that support the diagnosis include:
❑ increased serum lipase levels, which rise more slowly than serum amylase levels
❑ white blood cell counts that range from 8,000 to 20,000/µl, with increased polymorphonuclear leukocyte counts
❑ elevated glucose levels — as high as 500 to 900 mg/dl — indicating hyperglycemia.
An abdominal computed tomography scan with contrast is the most sensitive noninvasive test used to confirm the diagnosis of pancreatitis; however, abdominal ultrasound and abdominal magnetic resonance imaging also show pancreatic inflammation. Other tests that may show alterations include aspartate aminotransferase, carcinoembryonic antigen, fecal fat test, ionized calcium, lactate dehyrogenase (LD), LD isoenzymes, serum magnesium, and trypsinogen.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Cystic fibrosis:
Diagnosis
(Handbook of Diseases)
The Cystic Fibrosis Foundation sets the following standards for a definitive diagnosis:
❑ Two sweat tests using a pilocarpine solution (a sweat inducer) are clearly positive; the patient also has either an obstructive pulmonary disease, confirmed pancreatic insufficiency or failure to thrive, or a family history of cystic fibrosis.
Clinical tip Due to the large number of cystic fibrosis mutations, DNA analysis isn’t used for primary diagnosis.
❑ Chest X-rays indicate early signs of obstructive lung disease.
❑ Stool specimen analysis indicates the absence of trypsin, suggesting pancreatic insufficiency.
The following test results may support the diagnosis:
❑ Deoxyribonucleic acid testing can now locate the presence of the Delta F 508 deletion (found in about 70% of cystic fibrosis patients, although the disease is caused by more than 800 different mutations). This test can also be used for carrier detection and a prenatal diagnosis in families with a previously affected child.
❑ Pulmonary function tests reveal decreased vital capacity, elevated residual volume from air entrapments, and decreased forced expiratory volume in 1 second. This test is used if pulmonary exacerbation already exists.
❑ Liver enzyme test may reveal hepatic insufficiency.
❑ Sputum culture reveals organisms that cystic fibrosis patients typically and chronically colonize, such as Staphylococcus and Pseudomonas.
❑ Serum albumin levels help assess nutritional status.
❑ Electrolyte analysis assesses dehydration and glucose levels.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Pancreatic cancer:
Diagnosis
(Handbook of Diseases)
Definitive diagnosis requires a laparotomy with a biopsy. Other tests used to detect pancreatic cancer include:
❑ ultrasound — can identify a mass but not its histology
❑ computed tomography scan — similar to ultrasound but shows greater detail
❑ angiography — shows vascular supply of tumor
❑ endoscopic retrograde cholangiopancreatography — allows visualization, instillation of contrast medium, and specimen biopsy
❑ magnetic resonance imaging — shows tumor size and location in great detail.
Laboratory tests that can help support this diagnosis include serum bilirubin level (increased), serum amylase and serum lipase levels (sometimes elevated), prothrombin time (prolonged), and aspartate aminotransferase and alanine aminotransferase levels (elevations indicate necrosis of liver cells).
Additional pertinent studies include alkaline phosphatase level (marked elevation occurs with biliary obstruction), plasma insulin immunoassay (shows measurable serum insulin in the presence of islet cell tumors), hemoglobin level and hematocrit (may show mild anemia), fasting blood glucose level (may indicate hypoglycemia or hyperglycemia), and stool analysis (occult blood may signal ulceration in the GI tract or ampulla of Vater).
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
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