Urinalysis

The urinalysis is another common test routinely taken in almost all acute hospitals as an admission lab screening test. It can easily reveal renal and systemic pathologies. Everyone should be reminded of the importance of this test. It has become such a routine patient test, that often, care is not taken when collecting and handling specimens. This improper handling can affect the results of the test, since contamination can occur at any point in the handling.

Even the routine urinalysis should be a midstream specimen after cleansing the meatus. This does not require any special equipment or expense to the patient. Some hospitals will require that even the routine urinalysis be collected under sterile conditions just as a culture specimen would be collected. The container for this routine specimen should be clean; again, in some cases, the hospital requires a sterile container for all specimens. Remember that it will always save time in the long run to take care not to contaminate any type urine specimen.

The following tests are most common components of the urinalysis:

Test: Urinalysis: Appearance

Clinical Implications:

Turbidity and other terms are used to characterize the appearance of a urine specimen. Urine may contain red or white blood cells, bacteria, fat, or chyle and may reflect renal or urinary tract infection.

Some drugs can change the color of the urine. Normal urine color is a light yellow to a dark amber color. Inflammation may also cloud the urine as well as other pathological conditions can. Dorban can color the urine red; phenolphthalein can color it red; pyridium can color the urine dark orange. Of course, the patient should be "warned" of these changes. Hospitalization is stressful enough without the added shock of unexpected orange urine.

The odor of a urine specimen is also noted. In diabetes mellitus, starvation, and dehydration, a fruity odor accompanies formation of ketone bodies. In urinary tract infections, a fetid odor commonly is associated with E. coli. Maple syrup urine disease and phenylketonuria (PKU) also cause distinctive odors. Certain foods may also give urine certain color and odor. A patient diet history is important if the urine has an odor.

Test: Urinalysis: pH

Clinical Implications:

Urine is normally slightly acid (4.5 - 7.2 normal range). If alkaline, it can be indicative of infection. However, the urine pH does change during the day due to dietary influences and water intake. A 24-hour specimen would reveal an optimum pH of about 6.0.

Test: Specific Gravity

Specific gravity is the weight of the urine as compared to water.

Normal Values: 1.005 to 1.025

Clinical implications:

Specific Gravity will increase with the amount of dissolved particles (concentrated) in it. Specific gravity will decrease when the water content is high and the dissolved particles are low (less concentrated). Low specific gravity (<1.005) is characteristic of diabetes insipidus, nephrogenic diabetes insipidus, acute tubular necrosis, or pyelonephritis. Fixed specific gravity, in which values remain 1.010 regardless of fluid intake, occurs in chronic glomerulonephritis with severe renal damage. High specific gravity(>1.035) occurs in nephrotic syndrome, dehydration, acute glomerulonephritis, heart failure, liver failure, or shock.

Test: Urinalysis: Protein

Clinical Implications:

Only a very small amount of protein should be excreted into the urine in a 24-hour period (normal is 0-trace). Albumin is usually the first protein to be excreted in disease conditions. Some non-disease conditions such as extreme muscle exertion and pregnancy may cause proteinuria. Some of the disease conditions which can cause proteinuria are renal disease, fever, CHF, hypertension, tumors, and others.

Test: Urinalysis: Glucose and ketones

Clinical Implications:

The how and why glucose gets into the urine is dependent upon several factors. Without disease, it is possible to "spill" glucose after eating a large meal. Once serum glucose reaches 180 mg/100ml and above, it is possible to spill small amounts of glucose into the urine. This is a normal condition. However, some people have a higher or lower threshold for spilling glucose into the urine. A normal urine glucose is 0 to trace amounts.

Serum glucose levels are obviously important in diabetes, and so is the spilling of glucose into the urine. Glucose levels may also be raised or lowered in several other disease conditions as well as in diabetes.

Ketonuria occurs in diabetes mellitus when cellular energy needs exceed available cellular glucose. In the absence of glucose, cells metabolize fat for energy. Ketone bodies--the end products of incomplete fat metabolism--accumulate in plasma and are excreted in the urine. Ketonuria may also occur in starvation states and following diarrhea or vomiting.

Urinalysis: Microscopic exam of the urine

A microscopic examination of the urine may reveal many different disease conditions. The following tests are the usual components of the exam:

Test: Microscopic Urine Exam: RBC's

Clinical Implications:

This will detect the presence of RBC's in the urine. Normal is 0-3 RBC's. Gross bleeding into the urine is usually obvious. On lab exam of the urine, numerous, many, and gross are terms used to describe the amount of blood in gross bleeding. However, all bleeding is not that obvious. In order to detect slower bleeding and inflammation in the urinary tract, the microscopic exam is needed. In some normal conditions, a very few RBC's may get into the urine. When a level of more than 3 RBC's are found, a disease condition is often present. One of the most common causes of RBC's in the urine, is infection or inflammation of the urinary tract itself (i.e., cystitis). Trauma and several other conditions may also cause bleeding into the urine. Of course, the nurse will carefully observe the patient with gross bleeding. However, do not forget the patient with only very slight bleeding as well. This patient can just as easily develop a severe hemorrhage from only a "minor" condition.

Test: Microscopic exam of urine: WBC's

Clinical Implications:

WBC's are most often present in the urine due to direct infection/inflammation of the renal system. An infection in the urinary tract or in the kidney itself is usually the most common reason for this inflammation. However, there are also obstructive disorders which can cause WBC's to be in the urine. With obstructive disorders, however, there are usually other, more definitive symptoms present than only the WBC's present in the urine. The WBC count in the urine then, is not relied upon heavily to diagnose these obstructive disorders.

Test: Microscopic exam of urine: Casts

Clinical Implications:

Casts are solid, formed elements which appear in the urine, secondary to some other type of cell destruction. They can also be formed from other waste material as well as from dead cells. There are several different types of casts, named usually by the formation of their shape, or from their composition. Casts can be formed in the renal tubules and actually take the shape of the lumen of the tubules. They can also take other shapes and are named accordingly. The significance of casts in the urine is quite questionable. Casts formed from WBC's are noted more when infections are present. Likewise, certain diseases tend to form characteristic-type casts. However, diagnosis cannot be made definite from the presence of casts alone. This is true, because casts are influenced by the urine pH, by dehydration, inflammation and other such conditions.

Test: Microscopic exam of urine: Crystals and other components

Some crystals normally appear in urine, but numerous calcium oxalate crystals suggest hypercalcemia or ethylene glycol ingestion. Cystine crystals (cystinuria) reflect an inborn error of metabolism.

Bacteria, yeast cells, and parasites in urine sediment reflect genitourinary tract infection or contamination of external genitalia. Yeast cells, which may be mistaken for red blood cells, are identified by their ovoid shape, lack of color, variable size, and frequently, signs of budding. The most common parasite in sediment is Trichomonas vaginalis, which causes vaginitis, urethritis, and prostatovesiculitis.

Summary: Urinalysis

Some of the most common tests included in the urinalysis have been presented here. There are many other tests that can also be performed on urine, but most are not "routine" tests. Remember that routine tests will vary greatly in hospitals. What is routine in one hospital may not be routine in another. These may include the presence of crystals, bile, yeasts, acetone, and others.

When you are faced with one of these infrequent tests, it is best to ask the lab in your hospital for the correct procedure for collection of the specimens and transporting to the lab. Most nursing units also have lab manuals for that same purpose.

In all cases, the nurse should use care in the collecting and handling of the specimens. The results of the routine urinalysis can be used to help diagnose everything from dehydration to the rare metabolic disorders. The specimens themselves can be either random spot specimens or timed; depending upon the particular test. The urinalysis is almost always a random specimen, being refrigerated until delivered to the lab.

Test: Urinary Calculi

Urinary calculi (stones) are insoluble substances most commonly formed of the mineral salts--calcium oxalate, calcium phosphate, magnesium ammonium phosphate, urate, or cystine. They may appear anywhere in the urinary tract and range in size from microscopic to several centimeters.

Formation of calculi can result from reduced urinary volume, increased excretion of mineral salts, urinary stasis, pH changes, and decreased protective substances. Calculi commonly form in the kidney, pass into the ureter, and are excreted in the urine. Because not all calculi pass spontaneously, they may require surgical extraction. Calculi do not always cause symptoms, but when they do, hematuria is most common. If calculi obstruct the ureter, they may cause severe flank pain, dysuria, urinary retention, frequency, and urgency.

The procedure for this test is quite simple. The nurse will simply strain all the patient's urine and observe the strainer for any signs of calculi. Be sure to teach the patient to save all his urine. Many alert patients will be able to save and strain their own urine. Be sure to place a "SAVE URINE" sign at the bedside and in the patient's bathroom so that other health care workers will not discard any urine.

The nurse will send any stones, "gravel," or sediments strained to the lab according to hospital procedure. Also note any hematuria, flank pain, and any other symptoms. Many patients with renal calculi may be in severe pain and also might be groggy due to analgesics. Be sure to observe the proper nursing measure for these conditions.

Test: Concentration and Dilution Tests

The kidneys normally concentrate or dilute urine according to fluid intake. When such intake is excessive, the kidneys excrete more water in the urine. When intake is limited, they excrete less. This test evaluates renal capacity to concentrate urine in response to fluid deprivation, or to dilute it in response to fluid overload.

Preparation and procedure:

Explain the test to the patient. Explain that there will be certain food and fluid restrictions and requirements during the test period.

Concentration test:

  • Provide a high-protein meal and only 200 ml of fluid the night before the test.
  • Instruct the patient to restrict food and fluids for at least 14 hours before the test. (Some concentration tests require that water be withheld for 24 hours but permit a relatively normal food intake.)
  • Limit salt intake at the evening meal to prevent excessive thirst.
  • Emphasize to the patient that his cooperation is necessary to obtain accurate results.
  • Collect urine specimens at 6:00 a.m., 8:00 a.m., and 10:00 a.m.

Dilution Test:

  • Generally, this test directly follows the concentration test and necessitates no additional patient preparation. If it's performed alone, simply withhold breakfast.
  • Instruct the patient to void and discard the urine.
  • Give him 1,500 ml of water to drink within 30 minutes.
  • Collect urine specimens every half hour for 4 hours thereafter.

Normal Concentration results:
specific gravity: 1.025 to 1.032
Osmolality: >800 mOsm/kg

Normal Dilution Test results:
specific gravity: <1.0003
Osmolality: <100 mOsm/kg

Decreased renal capacity to concentrate or dilute urine may indicate tubular epithelial damage, decreased renal blood flow, loss of functional nephrons, or pituitary or cardiac dysfunction.

Cerebrospinal Fluid

Cerebrospinal fluid, CSF, is collected via the (LP) lumbar puncture. The nursing considerations include assisting with the LP and proper handling of the specimens. The actual procedure for the LP will vary at different hospitals, so the nurse should become thoroughly familiar with the procedure at each individual hospital. Most commonly today, specimen tubes are marked very clearly for the tests to be performed on that numbered specimen. The sterility of the specimen must also be maintained.

Test: cerebrospinal fluid examination, Pressure

Clinical Implications:

The cerebrospinal fluid pressure is measured during the extraction of the fluid at the LP site, by the physician. This is not a lab test, but it is important for the nurse to know its value.

Normal pressure is: 100 to 200 mm H2O

The most common cause of increased pressure of the fluid is increased intracranial pressure. There are also other conditions which can cause this, but they are quite rare.

Test: cerebrospinal fluid examination: Appearance

Clinical Implications:

CSF will change color according to the abnormal constituent:

  1. increased RBC's - red color
  2. increased WBC's - cloudy
  3. increased protein - cloudy
  4. severe jaundice - slightly yellow
  5. old blood - slightly yellow

The above abnormalities are easily detected, usually. The RBC's and WBC's may both be present in many inflammatory conditions and will be discussed later. Appearance then, can be a good indicator of the type of problem present and can lay suspect certain pathological conditions.

Test: Cerebrospinal fluid examination: Glucose

Clinical Implications:

CSF glucose levels are usually 1/2 of the serum glucose values (approx. 50-100 mg). The main pathologies occur when the CSF glucose is lower than normal. Decreased levels (45 mg and lower), are seen in meningitis, meningealcarcinoma and sometimes in intracranial hemorrhage.

Test: Cerebrospinal fluid examination: Protein

Clinical Implications:

Normal levels of protein are 15-40 mg. Some disorders which can cause an increase in protein, can also cause an increase in the WBC count as well. The following list of disorders can cause increased protein in the CSF, some also cause a corresponding elevation in WBC's:

  1. brain tumors
  2. some diabetics
  3. multiple sclerosis
  4. guillian-Barre syndrome
  5. syphilis

Test: Cerebrospinal Fluid Examination: Cell Count

Clinical Implications:

As discussed earlier, many disorders can cause increased cell counts in the spinal fluid. The first two specimen containers obtained will be contaminated with blood cells due to the trauma of the Lumbar Puncture itself.

Therefore, the cell count is usually performed on the last of the specimens taken. This is one of the reasons for correctly marking the specimen tubes as they are obtained. Most of the new disposable Lumbar Puncture trays today have conveniently pre-marked specimen containers for each successive specimen. This reduces the risk of mismarking the containers.

In most hospitals, a cell count is usually performed in order to detect the presence of infection. Upon examination, the lymphocytes are examined and their presence under 500mm3 may indicate a viral infection, or over 500mm3 may indicate purulent infections (increased granulocytes). In addition, a WBC differential count may be ordered so that the individual types of WBC's can be identified.

adult 0-8 leukocytes per cubic mm (mm3)
child 0-8 leukocytes per cu mm
newborn 0-15 leukocytes per cu mm
premature infant 0-20 leukocytes per cu mm

Test: Cerebrospinal fluid examination: Culture

Clinical Implications:

This test usually is performed when meningitis or other infection is suspected. In many hospitals a culture of the CSF is a routine procedure on all specimens collected.

Test: Cerebrospinal fluid examination: Serology

Definition: test for syphilis

Clinical Implications:

This test for CSF serology can have great clinical significance. Many times when the blood serology test is negative, the CSF test is positive. An example of this is: tertiary syphilis; where the serum test turns negative with time. There are also other times when the CSF test will be negative and the serum test will be positive. Each case must be evaluated individually. If syphilis is suspected, a CSF serology may be done in the presence of negative blood serology report from the lab.

Test: Cerebrospinal fluid examination

Soluble Amyloid Beta Protein Precursor

The presence of the amyloid beta protein in the senile plaques of the brain is a hallmark of Alzheimer's Disease, leading researchers to believe that this protein may be responsible for the disease's neurotoxic effects. Although amyloid is found in the CSF of healthy people, it is found in smaller amounts in some patients with dementia, making it a useful diagnostic tool.

Preparation and procedure:

Explain the test to the patient. The specimen is obtained through a lumbar puncture, so be sure to review your facility's guidelines for this procedure as well. There is usually no restriction of food or fluid, except some facilities prohibit a heavy meal right before the procedure.

  • The lumbar puncture is performed by the physician. Review the nursing implications of assisting with the LP and post-LP nursing care.
  • During the procedure, the physician will usually take routine measurements of the CFS such as pressure readings and CSF samples. Be sure you know ahead of time what samples are to be obtained. Some physicians prefer to take the one sample and "get out."
  • After the procedure, be sure to observe the patient for post-LP complications.
  • Mark the lab slip appropriately with the correct patient data, time of specimen collection, and the type of specimen (CSF).

Findings:

Soluble amyloid beta protein precursor is found in the CSF of healthy people. Normal amyloid beta protein levels in CSF are greater than 450 units/L, based on age-matched controls using the ELISA test.

Low CSF levels suggest an alteration in the amyloid beta protein precursor processing and amyloid beta protein formation. Low soluble amyloid beta protein precursor levels correlate with clinically diagnosed and autopsy-confirmed Alzheimer's disease.

Summary: Body Fluid Lab Tests

The tests presented here are the most commonly used tests in most hospitals today. There are other special tests which can be performed on these fluids, urine and spinal fluid, but usually just for rare conditions. There are also many other body fluids which may be tested. These include, but are not limited to:

synovial fluid, Pericardial fluid, pleural fluid, sweat, urogenital secretions, sputum, gastric acid, peritoneal fluid, fecal lipids, bile, semen, amniotic fluid, and many others

As we stated earlier, the nurse can be instrumental in the success of treatment of the patient, if those suggestions are followed. These diseases are serious ones which need the cooperation of the entire health care team.

Those suggestions are:

  • proper assistance during the lumbar puncture, urine collection, gastric aspiration, amniocentesis, etc.
  • Be sure to completely explain the test to the patient.
  • Be sure to obtain the proper consent forms (when required).
  • careful handling and transporting of the specimens
  • accurate recording and reporting of the patient symptoms
  • Be sure to perform after-care on special procedure such as LP, amniocentesis, etc.
  • possible isolation precautions for the patient

The need for isolation may be great, so be careful to follow hospital guidelines for handling suspected contagious fluids, such as meningitis patients, hepatitis patients, (and other infections).