What is he major functional unit of the kidney? - Answer- nephron
Approximately how many nephrons are there per kidney? - Answer- 1 million
The
... [Show More] nephron is composed of? - Answer- glomerulus, renal tubules
What is a glomerulus composed of? - Answer- capillary vessels
What is the function of a glomerulus? - Answer- non-selective filter of plasma substances less than 70k MW
What substances comprise the glomerular fjiltrate? - Answer- water, glucose, electrolytes, amino acids, urea, uric acid, creatinine, ammonia
What is the function of the proximal tubule? - Answer- reabsorbs water, NaCl, HCO3, K, Ca, amino acids, PO4, protein, glucose
Glucose is a threshold substance that reabsorbs within the proximal tubule at? - Answer- 160 - 189 mg/dl or less
What does the descending loop of henle reabsorb? - Answer- water
What doesn't the descending loop of henle reabsorb? - Answer- solutes
What does the ascending loop of henle reabsorb? - Answer- solutes (Na, Cl, Ca, Mg)
What doesn't the ascending loop of henle reabsorb? - Answer- water
What do the distal and collecting tubules reabsorb? - Answer- Na
What do the distal and collecting tubules secrete? - Answer- K, NH4, H+
Potassium ions are exchanged for what in the distal and collecting tubules? - Answer- Na ions
What is the rate of filtration of the glomerulus? - Answer- 120 ml/min or 1/5 of renal plasma
What is the normal amount of urine excreted per day? - Answer- 1200 - 1500 ml/day
Polyuria is defined as? - Answer- greater than 2500 ml of urine excreted per day (excess urine excretion)
What conditions can cause polyuria? - Answer- diabetes insipidus, diabetes mellitus, diuretics, caffeine, alcohol
Oliguria is defined as? - Answer- less than 500 ml of urine excreted per day (decreased urine excretion)
What conditions can cause oliguria? - Answer- dehydration, vomiting, diarrhea, burns, perspiration
Anuria is defined as? - Answer- complete cessation of urination
What conditions can cause anuria? - Answer- kidney damage, decreased blood flow to kidneys
Nocturia is defined as? - Answer- increased urine volume at night?
Urine is composed of? - Answer- urea, uric acid, creatinine, inorganic solids (Cl, Na, K), water
What is a metabolic waste product produced in liver from breakdown of protein? - Answer- urea
Aldosterone is secreted from? - Answer- adrenal cortex
What is the function of aldosterone? - Answer- increases the rate of sodium reabsorption
Arginine Vasopressin (AVP/ADH) is secreted from? - Answer- posterior pituitary gland
What is the function of AVP? - Answer- reabsoprtion of water from the distal tubules
A deficiency of AVP occurs in what condition? - Answer- diabetes insipidus
Erythropoietin (EPO) is secreted from? - Answer- kidney
What is the function of EPO? - Answer- stimulates production of erythrocytes
What type of urine specimen is considered ideal? - Answer- first morning (most concentrated)
What type of urine specimen is ideas for a bacterial culture? - Answer- midstream clean catch
Catheterization involves? - Answer- inserting a catheter directly into the bladder via the urethra
Catheterization avoids? - Answer- external contamination (may introduce an infection though)
Pediatric urine specimens are collected by? - Answer- placing a plastic collection bag over the genital area (many sources of contamination associated with this collection method)
Suprapubic aspiration specimens are collected by? - Answer- inserting a needle through the suprapubic abdominal area directly into the bladder
Suprapubic aspirations avoid? - Answer- external contamination
What are negative aspects of suprapubic aspirations? - Answer- invasive, may introduce infection
What is the optimal specimen collection method for bacterial cultures? - Answer- suprapubic aspiration
24 hour urine specimens are used for? - Answer- quantitative urine studies
How is the completeness of a 24 hour urine determined? - Answer- creatinine levels (should be greater than 1.0 mg/dl)
Urines should be analyzed within what timeframe of voiding? - Answer- 1 hour
What values increase as a result of prolonged sitting of urine specimens? - Answer- nitrite (bacterial growth), pH (urea is converted into ammonia), turbidity (bacterial growth/amorphous material)
What values decrease as a result of prolonged sitting of urine specimens? - Answer- glucose (glycolysis due to bacteria/yeast), ketones (volatization), bilirubin (exposure to light), urobilinogen (oxidation), cells/casts (lysis)
Urines can be preserved for how long? - Answer- 24 hours
What is the preservation method of choice for urines? - Answer- refrigeration
What may result if urines are preserved in a refrigerator? - Answer- precipitation of amorphous crystals
A fruity odor associated with urine can be attributed to the presence? - Answer- ketones
An ammonia-like odor associated with urine can be attributed to? - Answer- the age of the urine (old)
A mousy odor associated with urine can be attributed to what condition? - Answer- PKU (phenylketonuria)
A maple syrup like odor associated with urine can be attributed to what condition? - Answer- maple syrup disease
What compound gives urine its normal color? - Answer- urochrome
What type of urine specimen may be more on the alkaline side? - Answer- postprandial (2 hours after eating)
What is the typical pH of a normal urine? - Answer- 6.0
The pH of a random urine can range from? - Answer- 4.5 - 8.0
What can cause a urine to be cloudy? - Answer- cells, casts, crystals, bacteria
The presence of what substances can cause urine to appear more red? - Answer- hemoglobin, RBCs, myoglobin, porphyrin, uroerythrin
The presence of what substances can cause urine to appear more red-brown? - Answer- hemoglobin, RBCs, myoglobin
The presence of what substances can cause urine to appear more yellow-brown/amber-yellow-green? - Answer- bilirubin, biliverdin
The presence of what substance can cause urine to appear more yellow-orange? - Answer- bilirubin, urobilin, pyridium (drug)
The presence of what substances can cause urine to appear bright yellow? - Answer- vitamin C
The presence of what substances can cause urine to appear dark yellow? - Answer- concentrated specimen, bilirubin, urobilin
The presence of what substances can cause urine to appear brown-black? - Answer- methemoglobin (oxidized RBCs), homogentistic acid (alkaptonuria), melanin
The presence of what substances can cause urine to appear blue? - Answer- indican (tryptophan metabolic disorder)
The presence of what substances can cause urine to appear green/blue-green? - Answer- old urine, psuedomonas
The presence of what substances can cause urine to appear port wine? - Answer- porphyrin
The urine pH of a vegetarian is usually more? - Answer- alkaline
What can cause urine to become more acidic? - Answer- metabolic or respiratory acidosis, high protein diet, cranberry juice
Specific gravity measurements can help determine? - Answer- the concentration and dilution function of the kidney tubules
What is the normal specific gravity of urine? - Answer- 1.002 - 1.035
What is the highest specific gravity value that the kidneys can concentrate? - Answer- 1.040
Increased specific gravity values can be attributed to? - Answer- large amounts of glucose, radio-opaque dyes (renal x-ray procedures)
Decreased specific gravity values can be attributed to? - Answer- diabetes insipidus
Specific gravity is proportional to? - Answer- color (the higher the SG the deeper the color)
What is the defect associated with diabetes mellitus? - Answer- decreased insulin
What is the defect associated with diabetes insipidus? - Answer- decreased AVP/ADH
What symptoms are seen in both diabetes insipidus and mellitus? - Answer- polyuria, polydipsia
What substances are increased in the urine of an individual with diabetes mellitus? - Answer- specific gravity, glucose, ketones
What substances are decreased in an individual with diabetes insipidus? - Answer- specific gravity
Urinary measurments of glucose and ketones are normal in what type of diabetes? - Answer- insipidus
Refractometers measure? - Answer- the refractive index of urine
Corrections must be made with refractometers in the case of? - Answer- large amounts of protein
How do you correct a SG value higher than 1.035? - Answer- dilute the urine specimen 1:2 with water and multiply the last 2 digits of the result by 2
What is the principle of the measurement of protein in the urine? - Answer- protein error of indicators
What causes the change in color indicating the presence of protein on a urine dipstick? - Answer- albumin binding to the dye which shifts the dye's spectrum os the color changes from yellow to green
The presence of protein in the urine can be quantified by? - Answer- precipitation methods (sulfosalicylic acid)
How can highly alkaline urine affect protein measurements? - Answer- false positive
How can sulfosalicylic acid and penicillin affect protein measurements? - Answer- false positive
What is the best single indicator of renal abnormalities? - Answer- proteinuria
Proteinuria is associated with what conditions? - Answer- multiple myeloma, orthostatic proteinuria, strenuous exercise
What is orthostatic proteinuria? - Answer- a benign condition which results in proteinuria after standing
Periodic monitoring of microalbuminuria benefits patients with what conditions? - Answer- diabetes, hypertension, peripheral vascular disease
What substance is in such low quantities that routine reagent strips cannot detect its presence? - Answer- microalbumin
What is the methodology behind the measurement of glucose on a dipstick? - Answer- glucose oxidase (double) sequential enzyme reaction)
A positive copper reduction test with a negative dipstick test indicates? - Answer- a sugar (or other reducing substance) other than glucose
Which is more sensitive: copper reduction test or glucose dipstick? - Answer- dipstick
What interferes with the measurement of glucose on a dipstick? - Answer- bleach (false positive)
What is the purpose for using a clinitest tablet? - Answer- to detect the presence of other reducing sugars as well as glucose
What is the methodology behind the clinitest tablet? - Answer- benedict's copper reduction test (CuSO4 + NaOH + reducing substance = Cu2O)
In benedict's copper reduction test sugars and other reducing substances reduce what substance into? - Answer- cupric ion to the cuprous state (in the presence of alkali and heat)
The clinitest tablet is generally used as a screening test for? - Answer- galactosemia (a rare congenital carbohydrate metabolic condition in pediatric patients)
What is the principle of ketone testing performed with a dipstick? - Answer- sodium nitroprusside + ketone = purple color
What is the dipstick actually detecting when testing for the presence of ketones? - Answer- diacetic acid
What confirmation test is used to confirm the presence of ketones in the urine? - Answer- acetest tablets
What are the end products of fat metabolism? - Answer- acetone, diacetic acid (acetoacetate), beta-hydroxy-butyric acid
What interferes with the measurement of ketones in the urine? - Answer- highly pigmented urine, levadopa metabolites
Uncontrolled diabetes mellitus, high protein diets and GI disturbances can cause what types of results when testing for ketones? - Answer- positive
What is the 2-step enzymatic procedure that detects the presence of blood in the urine? - Answer- peroxide on strip + blood = O2, O2 + color producer = color change
What substances can result in false positive results when testing for the presence of blood? - Answer- bleach, other oxidizing substances
What substance can result in false negative results when testing for the presence of blood? - Answer- vitamin C
What other substances also exhibit peroxidase activity? - Answer- hemoglobin, myoglobin
Hematuria is associated with what clinical conditions? - Answer- systemic bleeding disorders, renal diseases, cystitis, calculi, strenuous exercise
Hemoglobinuria is associated with what clinical conditions? - Answer- hemolytic anemias, incompatible transfusions, malaria, strenuous exercise
Myoglobinuria is associated with what clinical conditions? - Answer- muscle destruction
What is the principle behind the detection of bilirubin in the urine? - Answer- (diazo reaction) diazonium salt + bilirubin = bluish purple color
Which is more sensitive in the detection of bilirubin: Ictotest tablet or dipstick? - Answer- ictotest
What substances can lead to false positives in the detection of bilirubin? - Answer- vitamin C, nitrite [Show Less]