Urinalysis Flashcards
What function are you looking for with 24 hour urinalysis tests?
Kidney function and Adrenal function
What 3 tests make up the complete urinalysis?
Gross Evaluation/Macroscopic Exam
Urine Dipstick
Microscopic Exam
How much plasma per day do the kidneys filter?
170,000 mL
How much urine is produced per day on average?
1,200 mL
What are the main filtering systems of the kidney?
The glomeruli
Where does reabsorption and secretion occur in the kidney?
The renal tubules
What makes up a nephron?
A glomerulus and a tubule
Where do urine concentration and dilution occur?
the medulla of the kidney
Describe what makes up urine.
95% water
2% urea
50% of dissolved particles are in the urea
Describe proper urine specimen collection.
Clean, dry container.
Clean external genitalia.
Collect midstream.
If catheterized, collect from tubing, not bag.
Describe proper urinalysis evaluation.
Room temperature.
Within 1-2 hours.
Otherwise, refrigerate, then rewarm to room temperature.
What does normal urine look like?
Clear/hazy.
Light yellow.
Why would urine be turbid or cloudy?
Abundance of cells (WBC, RBC, epithelial cells)
Bacteria
Contamination (talcum powder, vaginal cream)
Why would urine appear red?
Hematuria. Hemoglobinuria. Myoglobin. Menstrual contamination. Medications. Food dyes, beets, rhubarb
Why might urine appear orange?
Medications
Large amount of carrot consumption
Why might urine appear green?
Medications
Bilirubin
Pseudomonas infection
What does specific gravity measure?
Density of dissolved chemicals in the urine.
(Dilute or Concentrated)
Hyposthenuria - dilute - Diabetes Insipidus, Glomerulonephritis
Hypersthenuria - concentrated - DM, CHF, dehydration
What is the normal range of specific gravity?
1.005 - 1.030
What is the normal ph range of urine?
4.6 - 8.0, average 6.0
What conditions may trigger an abnormal urine pH?
Acidic
Metabolic - starvation, dehydration
Respiratory - COPD (CO2 retention)
UTI - E. coli
Alkaline - Chronic Renal Failure
What does the Leukocyte esterase test detect?
The presence of Leukocytes in the urine by detecting the enzyme leukocyte esterase, which is produced in response to an infection (UTI).
What is the term for leukocytes in the urine?
Pyuria
How reliable is the Leukocyte Esterase test?
False Positives are possible - vaginal discharge
Negatives are normal, but false negatives are possible.
What three things does the blood test for urine dipstick test?
Hematuria - intact RBCs in the urine
Hemoglobinuria - lysed RBCs in the urine, releasing free hemoglobin
Myoglobinuria - myoglobin from muscle cells
What conditions may cause hematuria?
Damage to the Kidney or urinary tract by:
Infection, Cancer, Kidney Stones, Strenuous Exercise, Smoking
What conditions may cause hemoglobinuria?
Extensive burns
Malaria
Hemolytic Diseases (sickle cell, thalassemia)
What conditions may result in myoglobinuria?
traumatic muscle injury
muscle disorder
How well can you trust the blood test from a urine dipstick?
False positives are possible, from menstrual bleeding
The test is highly sensitive, so false negatives are unlikely.
What is the nitrite test on the urine dipstick testing for?
The presence of nitrites, which are formed from gram negative bacteria converting nitrates into nitrites. This indicates a UTI.
How reliable is the nitrite test on the urine dipstick?
False positives and false negatives are possible.
False negatives may come from drinking cranberry juice, which lowers pH back into more of a normal range.
What does the ketone test on the urine dipstick test evaluate?
The presence of acetone, which is a byproduct of the metabolism of ketones. It represents an abnormal condition in which lipids are being metabolized at a high rate (as opposed to carbohydrates).
What conditions may elicit a positive ketone test on the urine dipstick?
Metabolic abnormalities: DM, hyperthyroidism
Dietary issues: vomiting, diarrhea, anorexia, high fat/low carb diet
In a patient with Diabetes Mellitus, what would be alarming about a positive ketone test on the urine dipstick?
Ketones in the urine of a diabetic would show that their glucose is not being consumed, fats are being metabolized, and they may go into a diabetic coma.
Where does bilirubin come from?
Product of hemoglobin breakdown
What conditions might cause bilirubin in the urine?
Liver dysfunction (hepatitis or cirrhosis) Biliary tract obstruction
Describe the two types of bilirubin.
Conjugated/Direct - formed by the liver to become water soluble. This is the only form found in the urine.
Unconjugated/ Indirect - has not yet been broken down by the liver and is not water soluble. Will not be found in urine.
How much bilirubin should be in the urine before you investigate further?
Even trace amounts of bilirubin warrant further investigation
Why might you find protein in the urine?
Normally, protein is stopped by the glomeruli from getting in the urine. Finding protein in the urine would indicate renal disease
What are the interchangeable terms for protein in the urine?
Proteinuria and Albuminuria
What is the single most important indicator of renal disease?
Protein in the urine.
What other conditions might cause protein in the urine?
Infection Stress Leukemia Pre-eclampsia Kidney stones
How much protein can you find in urine before you investigate further?
Even trace amounts of protein should be investigated.
Under what circumstances may you find glucose in the urine?
When the body has lost its ability to reabsorb glucose.
Diabetes Mellitus
Gestational Diabetes
When should a microscopic urine examination be ordered and what is its purpose?
It should be ordered if there are unexpected findings on the dipstick or if kidney disease is suspected.
It confirms and clarifies dipstick results and examines microorganisms, cells, casts, and crystals not evaluated by the dipstick.
If a microorganism is found, how should you proceed with your patient?
The presence of a microorganism should be guided by their symptoms.
What types of cells might you find in a microscopic examination?
Red Blood Cells White Blood Cells Epithelial Cells from the urinary tract (Renal epithelial cells should be investigated further!) Rarely you might find cancer cells
What are some reasons you might find crystals in the urine?
Could be a normal finding
Kidney stones
Certain medications
What are the most common crystals found in the urine?
Calcium oxalate crystals
May indicate renal failure, kidney stones, or high doses of ascorbic acid/vitamin C
What does a red blood cell cast indicate?
Bleeding in the nephron, usually from glomerulonephritis
What do white blood cell casts indicate?
Infection or inflammation within the kidney
commonly pyelonephritis
What do epithelial cell casts indicate?
(Rare)
Desquamation of tubule epithelium, possibly due to viral or toxin exposure.
What do hyaline casts indicate?
Generally nonspecific, common finding
What might granular casts indicate?
Degeneration of cellular casts, or direct accumulation of proteins.
Darker pigmented casts may indicate acute tubular necrosis.
What do waxy casts indicate?
Degeneration of granular casts.
Form from renal stasis (decreased flow), and indicate severe renal failure or nephrotic syndrome.
When might you see a fatty cast?
When fat accumulates with a protein matrix, may indicate nephrotic syndrome
What is the purpose of a urine culture?
To identify specific types of bacteria so you can prescribe the most effective medication.
Why might a patient benefit from a positive urine culture?
If they had a positive dipstick and have atypical symptoms.
If the first round of antibiotics were ineffective.
If symptoms reoccur within one month of a previous UTI.
How should a urine culture be obtained?
Midstream, in a sterile cup after proper disinfection of the meatus.
What is the purpose of a urine drug screen?
To help differentiate between drug induced symptoms and disease related symptoms.
Also, to detect drug abuse.
What types of drugs can be identified in the urine drug screen?
Most traditional recreational drugs, but not many newer ones.
What drugs are commonly tested for in the urine drug test?
Amphetamines, Barbiturates, Benzodiazepines, Cocaine, opiates, PCP (within two days)
marijuana (up to 30 days)
Alcohol, Heroin (must be within hours)
