Laboratory Tests To Evaluate Fluid Status
Laboratory Tests To Evaluate Fluid Status
Laboratory Tests To Evaluate Fluid Status
Serum Osmolality It is a test that measures the amount of chemicals dissolved in the liquid part (serum) of the blood. Chemicals that affect serum osmolality include sodium, chloride, bicarbonate, proteins, and sugar (glucose). It is done on a blood sample taken from a vein It is controlled partly by a hormone called antidiuretic hormone (ADH). Water constantly leaves your body as you breathe, sweat, and urinate. If you do not drink enough water, the concentration of chemicals in your blood (serum osmolality) increases. When serum osmolality increases, ADH is released. This increases the amount of water in the blood and helps restore serum osmolality to normal levels. When you drink too much water, serum osmolality decreases. When serum osmolality decreases, ADH is suppressed. This increases the amount of water in your urine and prevents too much
Why it is done?
Serum osmolality is measured to: Investigate hyponatremia which may be due to sodium loss through the urine or due to increased fluid in the bloodstream Check the balance between the water and the chemicals dissolved in blood. Find out if severe dehydration or overhydration is present. Check to see if the hypothalamus is producing enough antidiuretic hormone (ADH). Find the cause of seizures or coma. In severe cases, an imbalance between water and electrolytes in the body can cause seizures or coma. Find out if a person has swallowed certain poisons, such as rubbing alcohol (isopropanol), wood alcohol (methanol), or antifreeze (ethylene glycol). Serum osmolality can also help find out how much of these poisons are present in the blood.
When is it ordered?
A serum osmolality test and osmotic gap may be ordered when a person has symptoms that the doctor suspects may be due to hyponatremia such as: Excessive thirst Confusion Nausea Headache Lethargy In severe cases, seizures or coma These tests may be ordered when it is suspected that someone has ingested a toxin such as methanol or ethylene glycol.
How to prepare?
Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take. Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form
How is it done?
The health professional taking a sample of your blood will: Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein. Clean the needle site with alcohol. Put the needle into the vein. More than one needle stick may be needed. Attach a tube to the needle to fill it with blood. Remove the band from your arm when enough blood is collected. Put a gauze pad or cotton ball over the needle site as the needle is removed. Put pressure on the site and then put on a bandage.
How it feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
Risk
There is very little chance of a problem from having blood sample taken from a vein. You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes. In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this. Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.
Result
Normal 280303 milliosmoles per kilogram (mOSm/kg) of water (280303 mmol/kg of water) High values High serum osmolality levels may be caused by: Too little water in the body (dehydration). High levels of salt or sugar in the blood, such as poorly controlled diabetes and diabetic coma. A buildup of urea in the blood. Poisoning with certain substances, such as ethanol (the alcohol in alcoholic beverages), rubbing alcohol (isopropanol), wood alcohol (methanol), or antifreeze (ethylene glycol). A rare disease, such as diabetes insipidus, that causes the kidneys to produce large amounts of urine. Low values Low serum osmolality levels may be caused by: Too much water in the body (overhydration). A low level of salt in the blood. Overproduction of antidiuretic hormone (ADH) that may occur with some diseases, such as lung cancer.
It is frequently ordered along with serum osmolality. It is used to help evaluate the body's water balance and to investigate increased and decreased urine output. Increased urine output may be due to increased fluid intake, lack of appropriate amounts of ADH or due to diabetes, with increased glucose levels leading to increased urine output. Decreased urine output may be due to a variety of causes including decreased blood flow to the kidneys, an appropriate response to dehydration, or damage to tubular cells in the kidneys. Urine sodium and creatinine are often ordered along with urine osmolality. Sometimes a urine osmotic gap is calculated and used to help evaluate the kidney's ability to excrete acid and reabsorb bicarbonate, to detect the presence of osmotically active molecules, and to compare with the serum osmotic gap.
It may sometimes be ordered to help evaluate chronic diarrhea that does not appear to be due to a bacterial or parasitic infection or to another identifiable cause such as intestinal inflammation or damage.
Normal specific gravity range in urine human urine is from 1.003 to 1.030 a person could deduce certain information regarding the health of the test subject a urine test is a quick and inexpensive way to check the specific gravity in your urine
Equipment needed: Accurately calibrated urinometer (validate by measuring specific gravity of distilled water, which is 1.000), Multistix reagent test strips, or refractometer Clean, dry glass cylinder 20 ml urine or enough volume to fill glass cylinder two-thirds full Clean disposable gloves
6. Explain procedure to client and/or family member. Explain that urine must be free of feces and toilet tissue. 7. Wash hands and put on clean, disposable gloves. 8. If using urinometer, carefully pour fresh urine specimen into glass cylinder until it is two-thirds to three-quarters full. a. Place urinometer in cylinder of urine and gently twirl top of stem. b. Wait until urinometer stops bobbing; then with urinometer scale at eye level, read point where urine level touches calibrated scale. Read scale at lowest point of meniscus for best accuracy. Report abnormal findings to physician. c. Discard urine and wash cylinder and urinometer in cool water. 9. If using Multistix reagent strips, dip end of test strip (which is impregnated with a chemical reagent) into urine sample. After specified time (indicated on label) color of strip is compared with color chart on bottle. 10. If using refractometer, place one drop of urine on slide and view through refractometer, which allows visualization of density of urine on calibrated scale.
11.Remove and discard gloves, and wash hands. 12.Observe specimen for contaminants, feces, or toilet tissue. 13.Compare results of clients urinalysis with normal laboratory values. 14.If specific gravity is less than 1.010 or greater than 1.025, then: a. Continue to monitor client. b. Report findings to physician for further orders. 15.If urine contains feces or blood, then: a. Repeat specimen collection 16..Record specific gravity reading and note character of urine in nurses notes. 17. If clients I&O is being monitored, record urine volume on flow sheet. 18. Special flow sheets are available for recording frequent measurements of specific gravity. 19. Report abnormal values to physician.
Teaching Consideration:
1.Instruct client about proper method for collecting random urine specimen. 2. Explain reason for measuring specific gravity. 3. Discuss significance of test if client shows interest.
Pediatric Considerarion:
For infant and children who are not toilet trained, the urine specific gravity may obtain if cotton ball is left in the diaper area. Cotton ball may be removed if it is well saturated to obtain specimen.
Gerontological Consideration:
1.When obtaining specific gravity for older adult, note any medications that may influence results of sample. Some medications may cause alteration in true values. 2. When older adult is undergoing fluid restrictions, this may also have an impact on true specific gravity of urine. 3. The specific gravity decreases proportionately with advancing years in normal older adult (Malarkey and McMorrow, 2000).
The blood urea nitrogen (BUN, pronounced "B-U-N") test is a measure of the amount of nitrogen in the blood metabolism in the blood in the form of urea, and a measurement of renal function. Urea is a substance secreted by the liver , and removed from the blood by the kidney. Urea is formed by the liver and carried by the blood to the kidneys for excretion. Because urea is cleared from the bloodstream by the kidneys, a test measuring how much urea nitrogen remains in the blood can be used as a test of renal function. A BUN test is done to see how well your kidneys are working. If your kidneys are not able to remove urea from the blood normally, your BUN level rises. Heart failure, dehydration, or a diet high in protein can also make your BUN level higher. Liver disease or damage can lower your BUN level. A low BUN level can occur normally in the second or third trimester of pregnancy
A BUN test may be done with a blood creatinine test. The level of creatinine in your blood also tells how well your kidneys are working; a high creatinine level may mean your kidneys are not working properly.
Why it is done?
A blood urea nitrogen (BUN) test is done to: See if your kidneys are working normally. See if your kidney disease is getting worse. See if treatment of your kidney disease is working. See if severe dehydration is present. Dehydration generally causes BUN levels to rise more than creatinine levels. This causes a high BUN-to-creatinine ratio. Kidney disease or blockage of the flow of urine from your kidney causes both BUN and creatinine levels to go up.
How to prepare
Do not eat a lot of meat or other protein in the 24 hours before having blood urea nitrogen (BUN) test.
How is it done?
The health professional drawing blood will: Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein. Clean the needle site with alcohol. Put the needle into the vein. More than one needle stick may be needed. Attach a tube to the needle to fill it with blood. Remove the band from your arm when enough blood is collected. Put a gauze pad or cotton ball over the needle site as the needle is removed. Put pressure to the site and then a bandage.
How it feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
Creatinine is a chemical waste molecule that is generated from muscle metabolism. Creatinine is produced from creatinine, a molecule of major importance for energy production in muscles. Creatinine is transported through the bloodstream to the kidneys. The kidneys filter out most of the creatinine and dispose of it in the urine. It may be performed in two ways either through a blood sample or urine sample
How the Test is Performed Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding. In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
Normal result
A normal value is 0.8 to 1.4 mg/dL. Females usually have a lower creatinine than males, because they usually have less muscle mass.
Normal result
Urine creatine (24-hour sample) values can range from 500 to 2000 mg/day. Results are highly dependent on your age and amount of lean body mass.
A creatinine clearance test measures how well creatinine is removed from your blood by your kidneys. A creatinine clearance test gives better information than a blood creatinine test on how well your kidneys are working. A creatinine clearance test is done on both a blood sample and on a sample of urine collected over 24 hours (24-hour urine sample).
Normal result
A normal value is 90 to 110 ml/min.
The hematocrit is the proportion, by volume, of the blood that consists of red blood cells. The hematocrit (hct) is expressed as a percentage. For example, an hematocrit of 25% means that there are 25 milliliters of red blood cells in 100 milliliters of blood.
The age or gender of the person being tested may affect when and how often a lab test is required. Chronic or progressive conditions may need ongoing monitoring through the use of lab tests. Conditions that worsen and improve may also need frequent monitoring. Certain tests may be repeated to obtain a series of results, or tests may need to be repeated to confirm or disprove results. Timing and frequency of lab tests may vary if they are performed for professional or legal reasons.
Specimen required
Collect: 24-hour urine (no additive). Specimen must be refrigerated during collection. Also acceptable: random urine.. Storage/Transport Temperature: 1 mL aliquot from a well-mixed 24-hour or random collection at 2-8C. (Min: 0.2 mL) Remarks: Record total volume and collection time interval on transport tube and test request form. Do not use pH adjusted urine specimens. Stability (collection to initiation of testing): Ambient: 8 hours; Refrigerated: 1 week; Frozen: 3 months