Venous blood test

The other screening method currently used is a venous blood test, or the testing of blood taken from a child s vein. Some practices use the venous test on a regular basis to avoid having the false positives from finger stick tests and the need to retest. Finger sticks might be used, for example, only when a child will not sit still for the venous test. 

Sample Handling System. Venous or capillary blood, urine, and cerebrospinal fluid are specimens routinely used in medical diagnostic testing. Of these biological fluids, the use of venous blood is by far the most prevalent. Collection devices such as syringes and partial vacuum test tubes, eg, Vacutainer, are used to draw ten milliliters or less of venous blood. At collection time, the test tubes are carefully labeled for later identification. 

The testes are suspended outside the abdomen, in the scrotum, which is divided into two sacs, one for each testis. This location outside the abdominal cavity helps to maintain the testes at a temperature below normal (about 6°C lower) which is essential for satisfactory spermatogenesis. Indeed, the arterial and venous supply is so organised that it provides a heat exchange mechanism in which the arterial blood is cooled and the venous blood is warmed. The... 

Blood is drawn from healthy adult volunteers, who had no medication for the last two weeks. Venous blood (8.4 ml) is collected into 1.4 ml ACD-solution and centrifuged for 10 min at 120 x g. The platelet-rich plasma (PRP) is carefully removed, the pH adjusted to 6.5 with ACD-solution and centrifuged at 285 x g for 20 min. The resulting pellet is resuspended in Tyrode s buffer (approx. 500 xl buffer/10 ml PRP). The platelet suspension is applied immediately to a Sepharose CL 2B column equilibration and elution at 2 ml/min flow rate is done with Tyrode s buffer without hirudin and apyrase. Platelets are recovered in the void volume. Final platelet suspension is adjusted to 4 x 108/ml. Gel-filtered platelets (GFP) are kept at room temperature for 1 h until the test is started. 

The entire procedure is performed in plastic (polystyrene) tubes and carried out at room temperature. Blood is drawn from healthy adult volunteers, who had not received medication for the last 2 weeks. 9 ml venous blood are anti-coagulated with 1 ml of sodium citrate and kept in a closed tube at room temperature for 30-60 min until the start of the test. 

Corticotropin activity can be measured by the increase of corticosterone in venous blood of hypophysec-tomized or dexamethasone-blocked rats, as a singledose test when receptor affinity for ACTH receptor is found with a test compound. The test can be used to measure time-response curves of corticotropin preparations, and compounds with a adrenal stimulating activity (Vogel 1969a,b). The use of hypophysec-tomized rats for evaluation of the pituitary response... 

Blood for analysis may be obtained from veins, arteries, or capillaries. Venous blood is usually the specimen of choice, and venipuncture is the method for obtaining this speci-men. In young children and for many point-of-care tests, skin puncture is frequently used to obtain what is mostly capillary blood arterial puncture is used mainly for blood gas analyses. 

The Plasma Preparation Tube (Becton Dickinson, Franklin Lakes, New Jersey) is a plastic evacuated tube used for tire collection of venous blood that upon centrifugation separates undiluted plasma for use in molecular diagnostic test methods. 

Larsson-Cohn U. Differences between capillary and venous blood glucose during oral glucose tolerance tests. Scand J Clin Lab Invest 1976 36 805-8. 

Procedure The test is best performed in the morning after an overnight fast, but may be done at any time. Vigorous physical exercise (running or calisthenics) is performed for 20 minutes. A venous blood specimen for determination of GH is drawn immediately after termination of exercise. 

Formaldehyde is absorbed by the tissues of the respiratory traet during inhalation exposure in several species. Heck et al. (1985) determined the fate of inhaled formaldehyde in humans. Four men and two women were exposed to a 1.9 ppm air concentration of formaldehyde in a large walkin chamber for 40 minutes. Shortly before and shortly after the exposure, venous blood samples were taken from each person (each person served as his/her own control) and the blood was analyzed for formaldehyde content. Mean venous blood formaldehyde concentrations in humans prior to exposure showed a blood concentration of 2.61 0.41 g/g of blood. Individual variability was markedly present. Immediately after a 40-minute exposure, mean blood concentration of formaldehyde was 2.77 0.28 g/g of blood. There was no significant difference between pre- and postexposure blood concentrations of formaldehyde at the formaldehyde air concentrations tested in this study. This result suggests that formaldehyde was absorbed only into the tissues of the respiratory tract. The absence of increased formaldehyde concentrations in the blood is likely due to its rapid metabolism in these tissues and/or fast reaction with cellular macromolecules. 

A variety of specimens are used in biochemical analysis and the.se are shown in Table I. However, the inajoriiy of biochemical tests are perfonned on serum from venous blood or urine. 

Bicarbonate concentration is also determined directly as part of the electrolyte profile of tests on the laboratory s main analyzer, usually on a scrum specimen obtained from a venous blood sample. These results are not identical to the printout from the blood gas analyzer nor should this be expected since they include dissolved carbon dioxide, carbonic acid and other carbainino compounds. However, for pnicticiil purposes the results are similar and should not differ by more than mmol/1. They may, therefore, be interjireted in the same way. A low bicarbonate in an electrolyte profile will usually indicate the presence of a metabolic acidosis. 

Initially, urine (if available) should be tested for glucose and ketones, and blood checked for glucose using a test strip. Venous blood should be sent to the laboratory for plasma glucose and serum sodium, potassium, chloride, bicarbonate, urea ind creatinine. An arterial blood sample should also be sent for measurement of blood gases. 

Blood Venous blood samples are routinely collected for different laboratory tests and are suitable for molecular analysis. Blood contains a number of enzyme inhibitors that can interfere with downstream DNA analysis. In addition, common used anticoagulants such as heparin and EDTA can interfere with downstream assays as a consequence the DNA isolation from blood requires a standardized method to provide high-quality DNA without contaminants or enzyme inhibitors. 

Fat appears to be the main storage compartment in rats following inhalation exposure. In rats following an acute exposure to radon, concentrations of radon and radon daughters were much higher in the omental fat than in any of the other tissues examined, followed by the venous blood, brain, liver, kidney, heart, muscle tissues, and testes (Nussbaum and Hursh 1957). Radon reached equilibrium in the fat in about 6 hours compared to 1 hour in all other tissues. This may be due to the nonuniformity of blood perfusion within this tissue. 

Another issue in postmortem testing for ethanol is postmortem diffusion of ethanol from the stomach into the surrounding tissues. This phenomenon becomes evident within 48 h after death of individuals who died shortly after drinking sessions. In these cases, cardiac blood, blood in the thoracic and abdominal large vessels, pericardial fluid, and bile show falsely elevated levels of ethanol. Femoral venous blood, urine, and cerebrospinal fluid are relatively spared from ethanol diffusion from the stomach. However, vitreous humor is the best specimen of choice due to its anatomical location. 

In order to test this hypothesis it was necessary to compare populations with differing dietary practices but with similar exposure to environmental lead. The "Asian immigrant population in Britain, which is in fact derived from India and Pakistan, is known to differ in nutritional and cultural practices in comparison with the indigenous community. It is characterised by the prevalence of disorders of mineral metabolism including osteomalacia, and in the young, nutritional rickets and neonatal hypocalcaemia. A study was therefore undertaken in two towns located near London - Luton and Bedford - in which there are mutiracial populations (Strehlow and Barltrop 1978). Children from the Asian and non-Asian community aged 2-5 years were selected at random from computer-based local authority records and venous blood samples obtained for analysis. 

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