Specialized Chemistry
¿What is the Helicobacter pylori breath test and what conditions must the patient meet to perform it?
The carbon 13 labeled urea breath test (13C urea) is a rapid, non-invasive diagnostic test for Helicobacter pylori infection. It is also used to confirm that Helicobacter pylori has been completely eradicated after treatment.
Mass spectrometry equipment is used to perform this test, which has the ability to detect and measure the different carbon isotopes, including carbon 13 (13C), which is exhaled in the air of patients in whom the bacteria are found in their gastric mucosa.
During the test, the patient ingests 13C urea, which is converted by the activity of an enzyme called urease, produced by H. pylori, into ammonia and CO2; the latter is labeled with 13C and is released through the lungs and detected after at least 10 minutes.
For the test the patient must stop at least 4 weeks before the antibiotic treatment and up to 2 weeks before the proton pump inhibitors (e.g. omeprazole) and drugs with bismuth (e.g. Pepto-Bismol). In addition, the patient is required to fast for 8 to 12 hours on the day of the test. This test lasts approximately 20 minutes.
¿What special tests in this area support hematology studies? What diseases are they used for?
- Capillary electrophoresis tests of proteins, immunotyping of proteins in serum and immunofixation of proteins in urine:
These tests are used for the study of various diseases that affect the concentration of proteins in the blood and/or cause protein loss in the urine, such as occurs especially in plasma cell neoplasms. The basis of electrophoresis is based on separating proteins according to their size and electrical charge into subgroups: albumin and globulins (alpha-1, alpha-2, beta and gamma). Immunofixation is used to identify abnormal findings in protein electrophoresis, which correspond to a type of immunoglobulin.
- Capillary hemoglobin electrophoresis:
This test is used for the detection of qualitative and quantitative alterations of hemoglobin, the oxygen-carrying protein in red blood cells. There are several types of hemoglobin, both normal (hemoglobin A, A2 and F) and abnormal (hemoglobin S, C and E), which are detected with this test according to their physical characteristics and chemical properties.
It is used for the diagnosis of thalassemias, sickle cell anemia and other hemoglobin disorders, as a next step after abnormal findings in the blood count or blood smear, compatible symptoms and/or family history.
- Electrophoresis of von Willebrand multimers:
Von Willebrand factor is a glycoprotein present in the blood, which is involved in the adhesion of platelets to the vascular endothelium. Electrophoresis of von Willebrand multimers is one of the techniques used for the study of von Willebrand disease, a type of bleeding disorder, and subtype characterization (type 1, 2A, 2B, 2M, 2N, 3) by detecting and analyzing the distribution of von Willebrand factor multimers. The classification of von Willebrand’s disease is of great importance since treatment will depend on the type or subtype of the disease.
- Folate:
Folic acid, also known as vitamin B9, is a vitamin necessary for the maturation of structural proteins and hemoglobin. It also helps produce DNA and form red and white blood cells. Its measurement is requested to aid in the diagnosis of megaloblastic anemia or neuropathies, to monitor a person’s nutritional status (e.g. pregnant women) or the efficacy of treatment in cases of deficiency.
- Intrinsic factor:
Intrinsic factor is a protein produced by cells in the stomach lining to aid in the absorption of vitamin B12, which is needed for red blood cells to form and mature. Some people do not produce enough of it or destroy it. Its measurement is requested in cases of suspected pernicious anemia (indicated in patients with vitamin B12 deficiency) and for differential diagnosis between pernicious anemia and megaloblastic anemia.
¿What special tests in this area support the Clinical Chemistry studies? In which cases are they requested?
- Total and free prostate specific antigen (PSA):
PSA is a protein that, under normal conditions, is produced by prostate cells and is released into the seminal fluid. When the prostate is altered it leaks in greater quantities into the blood and can be detected in the blood. This is the most representative marker for prostate cancer screening in men between 45 and 75 years of age. It is also useful in the follow-up of low-grade prostate cancer cases.
Free PSA corresponds to the fraction of this protein that is free or is not forming complexes with other molecules in the blood. It is useful in differentiating between prostate cancer and benign prostatic conditions.
- Total Triiodothyronine (T3):
T3 is one of the hormones requested to assess thyroid gland function. In conjunction with thyroxine (T4), it controls energy utilization by the body; they also play an important role in controlling weight, body temperature, heart rate and nervous system function.
The total T3 test measures the amount of free T3 and T3 bound to other proteins that aid in its transport in the blood. There is another test called free T3 that measures only the free form of this hormone. The results of the T3 test are often compared with those of the T4 and TSH tests to diagnose thyroid dysfunction.
Measurement of total T3 is useful for diagnosing thyroid disease, especially hyperthyroidism, and determining its cause, as well as for monitoring known thyroid disease or evaluating the effectiveness of treatment.
- Antimullerian hormone (AMH):
AMH is a hormone produced in the testes in males and ovaries in females. Its function and amount is variable according to the age and sex of the individual. This hormone plays an important role in the development of the sexual organs of the fetus during the first weeks of pregnancy.
In women, levels remain low until puberty, when its concentration increases. Subsequently, it decreases steadily until it disappears after menopause. AMH levels accurately reflect the development of the ovarian follicle. The more eggs there are, the higher the AMH level. Its measurement is very useful in predicting ovarian reserve (how many eggs a woman has left) and establishing the likelihood of becoming pregnant. In addition, in the diagnosis of polycystic ovary syndrome, in assisted reproduction programs to evaluate the probability of response to treatment, as a marker of ovarian aging and prediction of the onset of menopause, as a marker of ovarian tumors, among other applications.
In men, its production decreases after puberty and remains at residual levels for the rest of life. Its measurement has allowed the evaluation of testicular function and states of hypogonadism, sexual differentiation disorders, pathological puberty, cryptorchidism, among other clinical conditions.
- Thyroglobulin:
- Glycosylated hemoglobin (HbA1c):
