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Exam of Urine

Chemical Examination of Urine Chpt. 5 Part 2 Protein and Glucose

What is a early indicative of renal disease on a routine chemical test performed on urine? protein
What is a normal 24hr range for protein? 100-125mg/24hr
What is the major serum protein found in normal urine and it's what the reagent strip is testing for? Albumin
What is the result of urinary albumin for a random specimen? negative
What is the normal amount of protein found in normal urine or first morning sample? less than 10mg/dL or 100 mg per 24 hours.
Even though albumin is present in high concentrations in the plasma, why is the content low in the urine? Because majority of albumin presented to the glomerulus is not filtered, and much of the filtered albumin is reabsorbed by the tubules.
What are some of the other proteins? small amounts of serum and tubular microglobulins, Tamm-Horsfall protein produced by the tubules, and proteins from prostatic, seminal, and vaginal secretions.
What is the range of clinical proteinuria? ≥30 mg/dL (300 mg/L)
What are the three categories of causes of proteinuria? prerenal, renal, and postrenal, which is based on the origin of the protein.
What does prerenal proteinuria mean? it's caused by conditions affecting the plasma prior to its reaching the kidney and, therefore, is not indicative of actual renal disease.
This condition is frequently transient, why? Because it's caused by increased levels of low-molecular weight plasma proteins such as hemoglobin, myoglobin, and the acute phase reactants associated with infection and inflammation.
What are some of the causes of transient proteinuria? Exercise, dehyration, fever, an Orthostatic Proteinuria.
What is Orthostatic proteinuria? It's a persistant benign proteinuria that occurs frequently in young adults from periods of vertical posture which puts pressure on the renal vein.
How do you test for Orthostatic proteinuria and what results would indicate that patient has this? Obtain a first morning sample which would be negative and get a second sample after remaining in the vertical position for several hours. The second sample would be positive.
Because reagent strips detect albumin, would prerenal proteinuria usually be discovered in a routine urinalysis? No
What do Bence Jones protein excretion indicate? Multiple Myeloma
What is multiple myeloma? a proliferative disorder of the immunoglobulin-producing plasma cells, the serum would contain markedly elevated levels of monoclonal immunoglobulin light chains(Bence-Jones protein).
How do you test for/determine it's the bence jones protein? Bence J. protein coagulates at temps b/w 40°C to 60°C and dissolves when the temp reaches 100°C. Specimen that appears turbid b/w 40 t0 60°C and clear at 100°C.
Renal Proteinuria is associated with? True renal disease caused by either glomerular or tubular damage.
What happens when you have a damaged glomerular membrane? selective filteration is impaired, and increased amounts of serum protein and eventually rbc and wbc pass through the membrane and are excreted in the urine.
What are some of the causes of glomerular proteinuria? Amyloid material, toxic substances, and the immune complexes found in lupus and streptococcal glomerulonephritis.
What is the amount of protein that appears in urine following glomerular damage? ranges from slightly above normal to 4g/day.
Why is increased albumin in the urine if it's tubular proteinuria? because the normally filtered albumin can no longer be reabsorbed.
What are some of the causes of tubular dysfunction? exposure to toxic substances and heavy metals, severe viral infections and Fanconi syndrome.
Are markedly elevated protein levels seldom seen in tubular disorders? No
Why isn't discovery of protein in a random sample not always pathologic significance? Because several benign causes of renal proteinuria exist, which is usually transient and can be produced by conditions such as strenuous exercise, high fever, dehydration, and exposure to cold.
What can Type 1 and type 2 diabetes mellitus cause? Diabetic nephropathy leading to a reduced glomerular filtration and eventual renal failure.
What can the onset of renal complications first be detected by? Microalbuminuria
What other condition can be associated with if the patient has microalbumin in their urine? Cardiovascular disease
What type of urine sample if required to detect microalbumin? 24-hr urine specimen
How are the results reported if testing for microalbumin? Using quantitiatve procedures results are reported in mg of albumin/24 hrs or as the albumin excretion (AER) in ug/min.
When is microalbumin considered significant? 30 to 300 mg of albumin is excreted in 24 hrs or the AER is 20-200 ug/min.
What does postrenal proteinuria mean? protein added to a urine specimen as it passes through the structures of the lower urinary tract(ureters, bladder, urethra, prostate, and vagina).
What are some of the causes of protein in postrenal proteinuria? prostatic fluid, seminal secretions(spermatozoa), vaginal secretions, bacteria and fungus.
What does protein error of indicators mean and why does this happen? Indicators change color in the presence of protein at a constant pH. Strong buffer, in protein pad, resists any change in urine pH. Therefor if protein is present, albumin will effect the color change BUT the pH in the pad does not change.
How are the results read for protein? negative, trace, 1+, 2+, 3+, and 4+; or semiquantitative values of 30, 100, 300, or 2000 mg/dL.
How are trace values considered? considered less than 30mg/dL. The specific gravity of the specimen should be considered b/c a trace protein in a dilute specimen is more significant than in a concentrated specimen.
How can highly buffered alkaline urine override the acid buffer system? Bacteria can increase the urinary pH,if the pH is >9, the buffer in the protein pad is OVERWHELMED. The color change that occurs is due to the pH change in the pad caused by the bacterial breakdown of urea; not b/c of presence of proteinuria.
What can cause a false positive reading with proteinuria? presence of bacteria which cause HIGH pH. reaction doesn't take place under acidic conditions, highly pigmented urine and contamination of the container with quaternary ammonium compounds, detergents, and antiseptics.
What causes false negative results with proteinuria? reagent strip only testing for albumin can result in a false- reading the presence of other proteins. Otherwise it's very rare or negligible.
What is the confirmatory test for urine protein? Sulfosalicyclic acid precipitation assay(SSA)
Explain SSA cold precipitation test that reacts with all forms of proteins, performed on centrifuged specimens, mix equal volumes of SSA with centrifuged urine and grade for turbidity.
What are some of the sources of errors associated with SSA? substances precipitated by acid produces false turbidity, highly alkaline urine produces false-neg. reading.
How would you know if you have a radiographic dye or other substances in urine for a SSA test? Radiographic material is suspected if their is a markedly elevated specific gravity and the turbidity also increases on standing due to the precipitation of crystals rather than protein.
Under normal conditions glucose should be: Negative in urine, almost all the glucose filtered by the glomerulus is reabsorbed in the proximal convolute tubule by active transport, Renal threshold is 160-180mg/dL.
How should urine samples be obtained for gluose monitoring? fasting sample, 2-hr post pranial and second sample preferred.
Why is the second voided sample after fasting preferred? The first morning sample does NOT always represent a fasting sample because glucose from the evening meal may remain in the bladder.
What is the Clinical significance of testing for Glucose in urine? Checking for diabetes mellitus, gestational diabetes, stress hormones(gluconeogenesis) Advance renal disease(glucose isn't reabsorbing back), Faconi's syndrome(overflow of glucose), and hormones that cause glycongenolysis.
What are the 2 different methods for glucose detection? Enzymatic(glucose oxidase or hexokinase) and Copper reduction?
What does glucose oxidase test for? specific for glucose
What do the reagent strip employ(for glucose oxidase) to test for glucose? by impregnating the testing area with a mixture of glucose oxidase, peroxidase, chromogen, and buffer to produce a double sequential enzyme reaction.
What are the steps that the reagent strips uses to test for glucose? Step one glucose oxidase catalyses the reaction b/w glucose and room air to produce glouconic acid and peroxide. The second step, peroxidase catalyzes the reaction b/w peroxide an chromogen to form an oxidized colored compound that represents glucose.
How is urine glucose results reported? Negative, trace, 1+, 2+, 3+, an 4+
How do false positive reactions occur with the glucose oxidase test? the container being contaminated with peroxide or strong oxidizing detergents.
How do false negatives reactions occur with the glucose oxidase test? by high levels of ascorbic acid, high levels of aspirin and low specific gravity, technical error of allowing specimens to remain unpreserved.
How does absorbic acid cause a false negative? by preventing oxidation of the chromogen.
What is the copper reduction test? It test for glucose and other reducing substances, such as galactose, aspirin, and vitamin C. The test relies on the ability of glucose and other substances to reduce copper sulfate to cuprous oxide in the presence of alkali and heat.
Explain the clinitest. Tablet contains copper sulfate, sodium carbonate, sodium citrate, and sodium hydroxide. You add tablet to urine & dilute with water. Sensitivity is 200mg/dL.
Explain the "pass through" The color produced passes through the orange/red stage and returns to a green-brown color
Compare glucose oxidase and clinitest 1+ reagent strip and neg. clinitest is okay because clinitest isn't as sensitive as the reagent strips but a strong positive strip and a neg clinitest test could mean contamination by strong oxidizing agents.
What is the most significant discrepancy with the glucose oxidase and clinitest? A negative reagent strip but a positve clinitest test. This could mean interference of other substances but usually means other sugars are present.
What are the false positives for the copper reduction method? all other reducing substances such as galactose, aspirin, ascorbic acid, an cephalosporins.
What are the false negatives for the copper reduction method? none because it's a rare finding.
Why is galactose in urine an important finding? galactose in urine in newborns represents "inborn error of metabolism" in which lack of the enzyme galactose-1-phosphate uridyl transferase prevents breakdown of ingested galactose causing complications and/or death.
Created by: Twixy565