Nursing 4 Lecture 4,5,6 LABS

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Nursing 4 Lecture 4,5,6 LABS
2012-01-30 17:56:41

Nursing 4 Lecture 4,5,6 LABS
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  1. BUN (blood urea nitrogen)
    • Normal:
    • Adult: 10-20 mg/dL
    • Elderly: may be slightly higher than an adult
    • Child and Infant: 5-18 mg/dL
    • Newborn: 3-12 mg/dL
    • Cord: 21-40 mg/dL

    CRITICAL: >100 mg/dL (indicates serious renal function)

    • Indications:
    • BUN is an indirect and rough measurement of renal function and glomerular filtration rate. It is also a measurement of liver function.

    • Interfering Factors:
    • -Low protein diets will decrease BUN if caloric intake is maintained with carbohydrates
    • -Gastrointestinal bledding will increase the levels
    • -Overhydration and underhydration will effect the levels
    • -Drugs that cause increased levels: allopurinol, cephalosporins, furosemide, methotrexate, aspirin, propranolol

    • Increased Levels:
    • Prerenal Causes-->
    • -Hypovolemia
    • -Shock
    • -Burns
    • -Dehydration
    • -CHF
    • -GI bleeding
    • -Excessive protein ingestion or catabolism
    • -Starvation
    • -Sepsis
    • Renal Causes-->
    • -Renal Disease
    • -Renal Failure
    • -Nephrotoxic drugs

    • Decreased Levels:
    • -Liver disease
    • -Overhydration
    • -Negative nitrogen balance
    • -Pregnancy
    • -Nephrotic syndrome
  2. Serum Creatinine
    • Normal:
    • Adult: Female- 0.5-1.1 mg/dL;Male- 0.6-1.2 mg/dL
    • Elderly: Decrease in muscle mass may cause decreased values
    • Adolescent: 0.5-1.0 mg/dL
    • Child: 0.3-0.7 mg/dL
    • Infant: 0.2-0.4 mg/dL
    • Newborn: 0.3-1.2 mg/dL

    CRITICAL: >4mg/dL (indicates serious impairment in renal function)

    • Indications:
    • Creatinine is used to diagnose impaired renal function.

    • Interfering Factors:
    • -Diets high in meat can cause elevations of creatinine
    • -Drugs that cause increased levels: ACE inhibitors, aminoglycosides (e.g. gentamicin), cimetidine, heavy-metal chemotherapeutic agents (e.g. cisplatin), and other nephrotoxic drugs such as cephalosporins (e.g. cefoxitin)

    • Increased Levels:
    • -Diseases affecting renal function, such as glomerulonephritis, pyelonephritis, acute tubular necrosis, urinary tract obstruction, reduced renal blood flow(e.g. shock, dehydration, CHF, atherosclerosis), diabetic nephropathy, nephritis
    • -Rhabdomyolysis
    • -Acromegaly
    • -Gigantism

    • Decreased Levels:
    • -Debilitation
    • -Decreased muscle mass(e.g. muscular dystrophy, myasthenia gravis)
  3. Creatinine Clearance (CrCl)
    • Normal:
    • Adult (<40 years): Male- 107-139 mL/min; Female: 87-107 mL/min
    • Values decrease 6.5 mL/min/decade of life after age 20 years with decline in glomerular filtration rate (GFR)
    • Newborn: 40-65 mL/min

    • Indications:
    • The creatinine clearance is used to measure the GFR of the kidney.

    • Interfering Factors:
    • -Exercise can increase values
    • -Incomplete urine collection may give falsely lowered value
    • -Pregnancy increases CrCl
    • -Diet in meat content can cause transient elevation of serum creatinine and CrCl
    • -Drugs that may cause increased levels: aminoglycosides(e.g. gentamicin), cimetidine, heavy-metal chemotherapeutic agents(e.g. cisplatin), and nephrotoxic drugs such as cephalosporins(e.g. cefoxitin)
    • -Drugs that may cause decreased levels: cimetidine or trimethoprim or cephalosporines

    • Procedure:
    • -Instruct the patient to begin the 24 hour urine collection (discard the initial specimen and start the 24 hour timing at that point)
    • -Collece the urine passed during the next 24 hours
    • -Show the patient where to store the urine specimen
    • -Keep the specimen on ice or refridgerated during the 24 hours
    • -Instruct the patient to void before defacating so that urine is not contaminated by feces
    • -Remind patient not to put toilet paper in the collection container
    • -Encourage the patient to drink fluids during the 24 hour collection unless this is contraindicated for medical purposes
    • -Instruct the patient to avoid vigorous exercise during the 24 hours because it can increase CrCl
    • -Collect the specimen as close to 24 hours as possible
    • -Make sure a venous blood sample is drawn in a red top tube during the 24 hour collection
    • -Mark the patients age, weight, and height on the requisition sheet
    • Increased Levels:
    • -Exercise
    • -Pregnancy
    • -High cardiac output syndromes

    • Decreased Levels:
    • -Impaired kidney function (e.g. renal artery atherosclerosis, glomerulonephritis, acute tubular necrosis)
    • -Conditions causing decreased GFR (e.g. CHF, cirrhosis with ascites, shock, dehydration)
  4. Intravenous Pyelography (IVP)
    • Normal:
    • Normal size, shape, and position of the kidneys, renal pelvis, ureters, and bladder.
    • Normal kidney excretory function as evidenced by the length of time for passage of contrast material through the kidneys

    • Indications:
    • The IVP is most commonly used radiologic test for evaluation of the urinary system, because much information about the kidneys, ureters, bladder, and prostate can be obtained. It is indicated in patients with:
    • -Pain compatible with urinary stones
    • -Blood in the urine
    • -Proposed pelvid surgery, to locate the ureters
    • -Trauma to the urinary system
    • -Urinary outlet obstruction
    • -Suspected kidney tumor

    • Contraindications:
    • -Patients who are allergic to shellfish or iodinated dyes
    • -Patients with severe dehydration, which can cause renal shutdown and failure (geriatric patients are particularly vulnerable)
    • -Patients with renal insufficiency, as evidenced by a BUN value greater than 40 mg/dL, because the iodinated nephrotoxic dye can worsen kidney function
    • -Patients with multiple myeloma, because the iodinated nephrotoxic dye can worsen renal function
    • -Patients who are pregnant, unless benefits outweigh the risk of radiation exposure to the fetus

    • Potential Complications:
    • -Infiltration of contrast dye: this is avoided by ensuring patency of the IV line. In the event of infiltration, a local injection of hyaluronidase may be given to hasten absorption of iodine and resolution of the reaction
    • -Renal failure: Most often occurs in elderly patients with chronic dehydration before the dye injection
    • -Hypoglycemia or acidosis may occur in patients who are taking metformin (glucophage) and receive iodine dye

    • Interfering Factors:
    • -Fecal material, gas, or barium in the bowel may prevent adequate visualization of the renal system
    • -Abnormal renal function studies may prevent adequate visualization of the urinary tract
    • -Retained barium from previous studies may obscure visualization; studies with barium should be scheduled after IVP

    • Procedure:
    • Before:
    • -Explain the procedure to the patient; inform the patient that several x-ray films will be obtained over 30 minutes
    • -Obtain informed consent
    • -Assess for allergy to iodine
    • -Give the patient a laxative the evening before the test
    • -Inform the patient of the required food and fluid restrictions; some prefer abstinence from solid foods for 8 hours before testing; some allow a clear liquid breakfast on the day of the test; for pediatric, elderly, and debilitated patients fasting times will be ordered on an individual basis
    • -Ensure adequate hydration (IV or oral) before and after the test to prevent dye-induced renal failure
    • -In patients receiving high rates of IV fluids infusion rates may be decreased for several hours before the study to increase the concentration of the dye within the urinary system
    • -Assess BUN and creatinine levels; Abnormal renal function could deteriorate as result of the dye injection
    • -Give the patient an enema or suppository on the morning of the study, if ordered
    • -Schedule any barium studies after completion of IVP
    • During:
    • Note the following steps-
    • 1. The patient is taken to radiology department and placed in the supine position
    • 2. An x-ray image of the abdomen is taken to ensure that no residual stool obscures visualization of the renal system; this also screens for calculi in the renal collecting system
    • 3. Skin testing for iodine allergy is often done
    • 4. A peripheral IV line is started and a contrast dye is given
    • 5. X-ray films are obtained at specific times (usually at 1, 5, 10, 15, 20, and 30 minutes, and sometimes longer after dye administration) to follow the course of the dye from the cortex of the kidney to the bladder
    • 6. Tomography may be performed to identify a mass
    • 7. The patient is taken to the bathroom and asked to void
    • 8. A postvoiding film is obtained to visualize the empty bladder
    • -Occasionally it is necessary to partially occlude the ureters temporarily to obtain a better film of the collecting system in the upper part of the ureters; this is done by compressing the abdomen slightly below the umbilicus
    • -The test is performed by a radiologist in approximatley 45 minutes
    • -Inform the patient that the dye injection often causes transitory flushing of the face, a feeling of warmth, a salty taste in the mouthe, or even transient nausea; Inital IV needle placement and lying on a hard x-ray table are the only other discomforts associated with IVP
    • After:
    • -Maintain adequate oral or IV hydration for several hours after IVP to counteract fluid depletion caused by the test preparation procedures
    • -Assess urinary output (decreased may be indication of renal failure)
    • -Evaluate elderly and debilitated patients for weakness because of the combination of fasting and catharsis necessary for test preparation- instruct these patients to ambulate only with assistance
    • -Evaluate the patient for delayed reaction to dye (e.g. dyspnea, rash, tachycardia, hives); Reactions usually occur within the first 2 to 6 hours after the test; Treat with antihistamines or steroids

    • Test Results & Clinical Significance:
    • -Pyelonephritis or glomerulonephritis: primary renal disease usually is evident as reduced opacification of the kidney with dye. This is because it takes a long time for enough dye to be filtered to the renal system to opacify the kidney
    • -Kidney tumor
    • -Renal hematoma or laceration
    • -Cyst or polycystic disease of the kidney
    • -Congenital abnormality of the urologic tract
    • -Renal or uretal calculi
    • -Trauma to the kidneys
    • -Tumor of the collecting system
    • -Hydronephrosis
    • -Extrinsic compressiong of the collecting system (caused by tumor or aneurysm)
    • -Bladder tumor
    • -Prostate enlargement
  5. Antistreptolysin O Titer (ASO Titer)
    • Normal:
    • Adult/Elderly: < or =160 Todd units/mL
    • Child:
    • -6 months to 2 years: < or = 50 Todd units/mL
    • -2 to 4 years: < or = Todd units/mL
    • -5 to 12 years: 170 to 330 Todd units/mL
    • -Newborn: similar to mothers value

    • Indication:
    • This test is used primarily to determine whether a previous streptococcus infection has caused a poststreptococcal disease, such as glomerulonephritis, rheumatic fever, bacterial endocarditis, and scarlet fever (levels are highest in glomerulonephritis and rheumatic fever)

    • Interfering Factors:
    • -Increased beta-lipoprotein levels can neutralize streptolysin O and can cause a false positive ASO titer
    • -Drugs that may caused decreased levels: adrenocorticosteroids and antibiotics

    • Increased Levels:
    • -Streptococcal infection
    • -Acute rheumatic fever
    • -Bacterial endocarditis
    • -Acute glomerulonephritis
    • -Scarlet fever
    • -Streptococcal pyoderma