BF - Exam 2 Flashcards
storage form of glucose found in liver and muscle
glycogen
describe pathway of glucose as it’s filtered and reabsorbed in nephron in normal/abnormal concentrations
Bowman’s capsule (glomerular filtration) → proximal convoluted tubule (reabsorption) → excretion through urine (if too much glucose)
renal threshold concept
- when excess glucose may be excreted
- 160-180 mg/dL
glycogenesis
process of converting glucose into glycogen for storage, primarily in liver and muscles
glycogenolysis
process of breaking down glycogen into glucose when energy is needed
how do reducing substances affect glucose testing on urine
- causes FN with ascorbic acid and other reducing agents
- causes FP with non-glucose reducing sugars (ex. galactose)
what is the significance of Clinitest and describe the pass-through phenomenon
- detects galactose in urine of infants
- NOT a confirmatory test for glucose
- pass-through phenomenon: occurs when high concentration of reducing substances (ex. galactose) causes color reaction to rapidly pass through expected positive color change and revert to lighter color, potentially giving a falsely low result
3 ketone bodies produced by human body
- acetone
- acetoacetic acid
- beta-hydroxybutyrate
how are ketone bodies produced in excess
when fat is metabolized to supply energy
what are Acetest tablets?
- confirmatory test for ketones
- provides better color differentiation and is more sensitive than dipstick
explain the importance of detecting orthostatic proteinuria
- condition where protein is found in urine only when person is standing, but not when lying down
- detecting it helps differentiate from be benign, short-term proteinuria from more serious kidney conditions
- prevents unnecessary treatments and helps with early detection if disease develops
Tamm-Horsfall protein
- aka uromodulin
- most abundant protein found in normal urine
- prevents UTIs, regulates kidney function, inhibits crystal formation
Bence-Jones protein
abnormal protein found in urine associated with multiple myeloma (type of blood cancer)
principle of the urine dipstick reaction for protein
protein error of indicator
describe the formation of bilirubin, urobilinogen and stercobilinogen (heme metabolism pathway; 9 steps and 5 info arrows)
- hbg –(broken down in spleen)→ heme → biliverdin → unconjugated/indirect bilirubin –(travels to liver)→ conjugated/direct bilirubin –(released into bile and then small intestine)→ some urobilinogen –(reabsorbed back into bloodstream and filtered by kidneys)→ urobilin
- rest of urobilinogen → stercobilinogen –(oxidized)→ stercobilin (gives stool its brown color)
direct/conjugated vs. indirect/unconjugated bilirubin
- direct: water soluable
- indirect: water insoluable
steatorrhea
presence of excess fat in stool, making stool appear pale, bulking, and greasy
urobilin
yellow pigment found in urine; formed from breakdown of urobilinogen
what is the Ictotest
- confirmatory test for pos bilirubin
- pos = blue-to-purple color
principle of the blood portion of the urine dipstick
pseudoperoxidase activity of hemoglobin and myoglobin
why does a negative test does not rule out a urinary tract infection (UTI)
could be other bacteria that just doesn’t convert nitrate to nitrite
principle of the leukocyte esterase dipstick test
- dipstick contains a substrate (usually an ester compound) that reacts with leukocyte esterase
- when leukocyte esterase is present in the urine, it hydrolyzes the substrate, breaking it down into a colored product (usually purple or pink)
- color change is proportional to the amount of leukocyte esterase in the urine, so the darker the color, the more leukocytes are present
how are urine dipsticks tests are affected by ascorbic acid (4)
- blood → inhibits peroxidase reaction
- glucose → interferes with glucose oxidase reaction
- bilirubin → reduces diazonium salt reaction
- nitrites → interferes with Greiss reaction
describe presence of each type of cast (8)
- hyaline → normal
- RBC → acute glomerulonephritis, subacute bacterial endocarditis, renal trauma, severe pyelonephritis
- WBC → pyelonephritis, acute interstitial nephritis, lupus nephritis, glomerular disease
- bacterial → pyelonephritis, infection
- epithelial cell → nephrotic agents, kidney allograft, viruses, glomerular/tubular injury, drug toxicity
- granular → renal disease
- waxy → severe chronic renal failure, malignant hypertension, acute renal disease, tubular inflammation and degeneration, renal allograft rejection
- fatty → toxic renal poisoning, SLE, glomerulonephritis, nephrotic syndrome**
describe presence of hemosiderin
when hbg is broken down and iron-containing hemosiderin is filtered by kidneys; caused by intravascular hemolysis
how do kidney stones form
composition crystalloids embedded in binding substance of mucous and protein forming hard deposits inside kidneys
Sternheimer Malbin
- crystal violet and safranin-O
- has stabilizers to prevent precipitation
- helps differentiate renal tubular epis from other epis
2% Acetic acid
enhances nuclear pattern of WBC and lyses RBCs
Lipid stains (Oil Red O and Sudan III)
stains triglycerides and neutral fats floating free in urine an orange or red
Prussian Blue
hemosiderin stains
name acid crystals in urine (2)
- amorphus urates
- uric acid
name alkaline crystals in urine (2)
- ammonium biurate
- calcium carbonate
