Pulmonary function tests (PFT) measure the volume and flow of air by utilizing a spirometer and compares against normal values. A spirometer is a device attached to a computer that measures the capacity of the lungs while the patient blows exhaled air from the lungs into the disposable mouthpiece.
The Mantoux tuberculin test, or purified protein derivative (PPD), is a type of intradermal skin test. A small extract from the tubercle bacillus is injected into the skin and results are read in 48–72 hours. Raising and hardening of the skin (called an induration) of 10 mm or more around the area indicates a possible positive reaction. Less than 5 mm induration is not considered a positive test; induration of 5–10 mm is equivocal (likely needs repeat or further testing). However, individuals vaccinated with bacille Calmette-Guerin (BCG) will also test positive even if they are not infected with TB; many foreign-born individuals have received BCG vaccination. When the tuberculin test is positive, other testing is then required, including a chest x-ray and sputum culture.
Guaiac reagent strips are used to detect the presence of occult blood in the stool. The test may detect bleeding in the GI tract that is undetectable with a visual inspection. This test is designed to detect hidden blood in the stool early enough for corrective measures to be taken. The patient collects stool samples on the reagent paper and sends the test in a leak-proof envelope to the laboratory.
The hemoglobin and hematocrit tests are used to detect iron-deficiency anemia and are often conducted in an office setting. They can be obtained simply and rapidly using the finger-stick method of blood collection. Hemoglobin (Hb) is the protein in red blood cells that carries oxygen to the tissues. It is measured using a device called a HemoCue and expressed in grams per deciliter (g/dl). Normal hemoglobin values vary based on gender and age, but adult hemoglobin is typically in the range of 12–18 g/dl. Hematocrit is the ratio of red blood cell volume to total blood volume and is expressed as a percentage of red blood cells. The specimen is collected into a microcapillary tube and then centrifuged, which concentrates the red blood cells at the bottom of the tube so that the total can be read on a scale. Normal adult hematocrit values are 36–55 percent.
Beta-hemolytic streptococcus group A is a major cause of serious bacterial throat infections. Left untreated, streptococcus can lead to rheumatic fever with associated heart and kidney complications, among other health problems. There are two tests for streptococcus: a throat swab placed in culture medium and incubated for 24–48 hours, and a CLIA-waived kit that provides immediate results. Whenever using a prepared kit for testing, use extreme care to avoid inaccurate results. This includes confirming that the kits are within their use dates (not expired), following the testing guidelines, and running positive and negative controls with the patient test.
Pregnancy testing can be rapidly and easily accomplished with a first morning urine specimen from the patient. A first morning urine specimen provides the greatest concentration of human chorionic gonadotropin (hCG), which is produced by the placenta shortly after embryonic attachment to the uterus. This test can detect pregnancy as early as two weeks after conception and is 97 percent accurate if performed correctly.
The Epstein-Barr virus (EBV) is a one of the most common infectious viruses, perhaps best known as the cause of infectious mononucleosis (IM). A common contagious disease, IM is sometimes called “the kissing disease” because transmission occurs via saliva. IM is difficult to detect because of the vague symptoms it presents. After the primary infection, the virus establishes latency in the victim that lasts for a lifetime. Rapid detection kits using a small amount of blood obtained via a finger-stick are available, but serologic tests in conjunction with clinical observations of the patient may be required to confirm diagnosis.