Laboratory Tests to Evaluate Fluid Status

8/4/2019 Laboratory Tests to Evaluate Fluid Status

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Laboratory Tests to Evaluate Fluid

Status

Reported by: Group 25 A&B


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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 tonormal 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


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Serum osmolality is measured to:

Investigate hyponatremia which may be due to sodium loss throughthe urine or due to increased fluid in the bloodstream

Check the balance between the water and the chemicals dissolvedin blood.

Find out if severe dehydration or overhydration is present.

Check to see if the hypothalamus is producing enough antidiuretichormone (ADH).

Find the cause of seizures or coma. In severe cases, an imbalancebetween water and electrolytes in the body can cause seizures orcoma.

Find out if a person has swallowed certain poisons, such as rubbingalcohol (isopropanol), wood alcohol (methanol), or antifreeze(ethylene glycol). Serum osmolality can also help find out howmuch of these poisons are present in the blood.

Why it is

done?


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A serum osmolality test and osmotic gap may be ordered when aperson has symptoms that the doctor suspects may be due tohyponatremia 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.

When is it

ordered?


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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 to

prepare?


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The health professional taking a sample of your blood will:

Wrap an elastic band around your upper arm to stop the flow ofblood. This makes the veins below the band larger so it is easier toput 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 isremoved.

Put pressure on the site and then put on a bandage.

How is it

done?


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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.

How it feels


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There is very little chance of a problem from having blood sampletaken from a vein.

You may get a small bruise at the site. You can lower the chance ofbruising 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 beused several times a day to treat this.

Ongoing bleeding can be a problem for people with bleedingdisorders. Aspirin, warfarin (Coumadin), and other blood-thinningmedicines can make bleeding more likely. If you have bleeding orclotting problems, or if you take blood-thinning medicine, tell yourdoctor before your blood sample is taken.

Risk


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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.

Result


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Results from a serum osmolality test may be affected by:

Drinking alcohol before the test.

Recently receiving a blood transfusion

What affect the

result


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It is frequently ordered along with serum osmolality.

It is used to help evaluate the body's water balance and toinvestigate increased and decreased urine output.

Increased urine output may be due to increased fluid intake, lack ofappropriate 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 todehydration, 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 reabsorbbicarbonate, to detect the presence of osmotically activemolecules, and to compare with the serum osmotic gap.


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Factors that affect osmolality

INCREASE DECREASE

Congestive Heart

Failure

hypernatremia

inappropriate ADHsecretion

liver damage

shock

Diabetes insipidus

Excess fluid intake

Hypercalcemia

HypokalemiaKidney tubular damage


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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.


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a test that measures the concentration of particles in the

urine.

measures the kidney's ability to concentrate or dilute urine in

relation to plasma

The more concentrated the urine, the higher the urine

specific gravity.

In infants, the range for specific gravity is less because

immature kidneys are not able to concentrate urine as

effectively as mature kidneys.

An adult's kidneys have a remarkable ability to concentrate or

dilute urine.

Urine Specific Gravity


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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


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Abnormal specific gravity value may indicate of:

Reduced specificgravity

Raised specific gravity

excess fluid intake

diabetes insipidus

certain renal (kidney)diseases

renal (kidney) failure

diabetes mellitus

Glomerulonephritisand pyelonephritis

dehydration

increased secretion of

antidiuretichormone (ADH)

Trauma, stress

reactions, surgery, and

many drugs

Constant Urine Specific Gravity Chronic renal

disorder


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Equipment needed:

Accurately calibrated urinometer (validate by measuringspecific 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-thirdsfull

Clean disposable gloves


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1. Assess clients or family members understanding of need to test specific

gravity and how test is performed.

2. Determine clients ability to collect specimen

3. Assess clients hydration status: skin turgor, condition of mucous

membranes, intake and output (I&O), integrity of fontanels (infants).4. Assess clients medical history for evidence of renal disease.

5. Expected outcomes following completion of procedure

a. Specific gravity is between 1.010 and 1.025.

b.There are no feces, blood, or toilet tissue in urine specimen.

Testing: Urine Specific Gravity


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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 eyelevel, 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.


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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 nursesnotes.

17. If clients I&O is being monitored, record urine volume on flow sheet.

18. Special flow sheets are available for recording frequent measurements ofspecific gravity.

19. Report abnormal values to physician.


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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.

Teaching Consideration:

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.


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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).

Gerontological Consideration:


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The blood urea nitrogen (BUN, pronounced "B-U-N") test is a

measure of the amount of nitrogen in the blood metabolism in theblood 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


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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.

Blood Urea Nitrogen to creatinine ration (BUN:Creatinine )


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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.

Why it is

done?


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Do not eat a lot of meat or other protein in the 24 hours

before having blood urea nitrogen (BUN) test.

How to

prepare


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The health professional drawing blood will:

Wrap an elastic band around your upper arm to stop the flowof 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 maybe 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 is it done?


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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.

How it feels


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Abnormal Blood Urea Nitrogen value may indicate of:

INCREASE DECREASEImpaired renal function

Congestive heart failure as

a result of poor renal

perfusion

Dehydration

Shock

Hemorrhage into the

gastrointestinal tract

Acute myocardial

infarctionStress

Excessive protein intake or

protein catabolism

Liver failure

Malnutrition

Anabolic steroid use

Over hydration, Which can

result from prolongedintravenous fluids

Pregnancy (due to

increased plasma volume)

Impaired nutrient

absorptionSyndrome of

inappropriate anti-diuretic

secretion (SIADH)


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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


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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 attachedto 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 maybe 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.


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The test is done to evaluate kidney function. Creatinine is

removed from the body entirely by the kidneys. If kidneyfunction is abnormal, creatinine levels will increase in theblood (because less creatinine is released through your urine).

Creatinine levels also vary according to a person's size and

muscle mass.

Why the test is performed

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.


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What abnormal result mean

HIGH LOW

Acute tubular necrosisDehydration

Diabetic nephropathy

Eclampsia(a condition of

pregnancy that includes

seizures)Glomerulonephritus

Kidney failure

Preeclampsia(pregnancy-

induced hypertension)

Pyelonephritis

Reduced kidney blood

flow (shock, congestive

heart failure)

Rhabdomyolyisis

Urinary tract obstruction

Muscular dystrophy (latestage)

Myasthenia gravis


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A random urine sample or a 24-hour collection may used.

How the test is performed

Why the test is performed

This test can be used as a screening test to evaluate kidneyfunction. It may also be used as part of the creatinine clerance

test. It is often used to provide information on other

chemicals in the urine such as albumin or protein.

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.


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sGlumerulonephritis High meat diet

Kidney failure

Muscular dystrophy (late stage)

Myasthenia gravis

Prerenal azotemia

Pyelonephritis

Reduced kidney blood flow (as in shock or congestive heart failure)

Rhabdomvolysis

Urinary tract obstruction



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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.


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HIGH LOWstrenuous exercise

muscle injury (especially

crushing injuries)

burnsCarbon monoxide

poisoning

Hypothyroidism

Pregnancy

serious kidney damage

can be from:

life-threatening infection,

shock, cancer, low bloodflow to the kidneys, or

urinary tract blockage.

Heart failure

dehydration

liver disease (cirrhosis)


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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.


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The hematocrit is typically measured from a blood sample by an

automated machine that makes several other measurements

at the same time. Most of these machines in fact do not

directly measure the hematocrit, but instead calculate it

based on the determination of the amount of hemoglobin andthe average volume of the red blood cells. The hematocrit can

also be determined by a manual method using a centrifuge.

When a tube of blood is centrifuged, the red cells will be

packed into the bottom of the tube. The proportion of redcells to the total blood volume can be visually measured.

How is the hematocrit measured


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The normal ranges for hematocrit are dependent on age and,

after adolescence, the sex of the individual. The normal

ranges are:

Newborns: 55%-68%

One (1) week of age: 47%-65% One (1) month of age: 37%-49%

Three (3) months of age: 30%-36%

One (1) year of age: 29%-41%

Ten (10) years of age: 36%-40% Adult males: 42%-54%

Adult women: 38%-46%

These values may vary slightly between laboratories.

What is normal hematocrit mean


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A low hematocrit is referred to as being anemic. There are many

reasons for anemia . Some of the more common reasons are

loss of blood (traumatic injury, surgery, bleeding colon

cancer), nutritional deficiency (iron, vitamin B12, folate), bone

marrow problems (replacement of bone marrow by cancer,suppression by chemotherapy drugs, kidney), and abnormal

hematocrit (sickle cell anemia).

What does low hematocrit mean


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Higher than normal hematocrit levels can be seen in people

living at high altitudes and in chronic smoker. Dehydration

produces a falsely high hematocrit that disappears when

proper fluid balance is restored. Some other infrequent

causes of elevated hematocrit are lung disease, certaintumors, a disorder of the bone marrow known as

polycythemia rubra vera, and abuse of the drug

erythropoietin (Epogen) by athletes for blood doping

purposes.

What does high hematocrit mean


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This test measures the amount of sodium in urine. It is used to

evaluate the status of the amount of fluid within the blood

vessels, and the electrolyte balance in the body. This test may

be used when conditions such as hyponatremia (low sodium

levels in the body) are suspected.

24 hours urine sodium output measurement


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Laboratory tests may be done for many reasons. Tests are

performed for routine health screenings or if a disease or

toxicity is suspected. Lab tests may be used to determine if a

medical condition is improving or worsening. Lab tests may

also be used to measure the success or failure of a medicationor treatment plan. Lab tests may be ordered for professional

or legal reasons. The following are possible reasons why this

test may be done:

Acute kidney failure Decreased blood sodium

Why do I need this test


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When and how often laboratory tests are done may depend onmany factors. The timing of laboratory tests may rely on theresults or completion of other tests, procedures, or treatments.Lab tests may be performed immediately in an emergency, ortests may be delayed as a condition is treated or monitored. Atest may be suggested or become necessary when certain signsor symptoms appear

Due to changes in the way your body naturally functions throughthe course of a day, lab tests may need to be performed at a

certain time of day. If you have prepared for a test by changingyour food or fluid intake, lab tests may be timed in accordancewith those changes. Timing of tests may be based on increasedand decreased levels of medications, drugs or other substancesin the body

When and how often should I have these test


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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 oflab 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.


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During a 24-hour urine collection, follow your usual diet and

drink fluids as you ordinarily would, unless healthcare workers

give you other instructions. Avoid drinking alcohol before and

during the urine collection

How should I get ready for these test


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For a 24-hour urine collection, all of the urine that you pass over a 24-

hour time period must be collected. If you are in the hospital, ahealthcare worker will collect your urine. You will receive a specialcontainer to collect the sample in if you are doing the collection athome. The following are directions for collecting a 24-hour urinesample while at home:

In the morning scheduled to begin the urine collection, urinate in

the toilet and flush away the first urine you pass. Write down thedate and time. That is the start date and time for the collection.

Collect all urine you pass, day and night, for 24 hours. Use thecontainer given to you to collect the urine. Avoid using othercontainers. The urine sample must include the last urine that youpass 24 hours after starting the collection. Do not allow toilet paper,stool, or anything else to be added to the urine sample.

Write down the date and time that the last sample is collected.

The urine sample may need to be kept cool during the 24-hourcollection period. If so, keep the closed container in a pan on ice.Do not put ice in the container with the urine

How these test done


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The amount of discomfort you feel will depend on many factors,

including your sensitivity to pain. Communicate how you are

feeling with the person doing the test. Inform the person

doing the test if you feel that you cannot continue with the

test.This test usually causes no discomfort

How the test feel


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Laboratory test results may vary depending on your age, gender,

health history, the method used for the test, and many otherfactors. If your results are different from the results suggestedbelow, this may not mean that you have a disease. Contact yourhealthcare worker if you have any questions. The following areconsidered to be normal results for this test:

Adults (varies with intake): 100-260 mEq/24-hours (100-260mmol/24-hours)

Full term neonates 7 to 14 days old: Sodium clearance is about 20%of adult values

Females 6 to 10 years: 20-69 mEq/day (20-69 mmol/day)

Males 6 to 10 years: 41-115 mEq/day (41-115 mmol/day)

Females 10 to 14 years: 48-168 mEq/day (48-168 mmol/day)

Males 10 to 14 years: 63-177 mEq/day (63-177 mmol/day)

What is normal result for these test


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Results decreased in: Over hydration

What may affect the result


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Collect: 24-hour urine (no additive). Specimen must be

refrigerated during collection. Also acceptable: randomurine..

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 timeinterval on transport tube and test request form. Do notuse pH adjusted urine specimens.

Stability (collection to initiation of testing): Ambient: 8hours; Refrigerated: 1 week; Frozen: 3 months

Specimen required

Documents

Laboratory Tests to Evaluate Fluid Status