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46 Cards in this Set
- Front
- Back
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describe the relative solubility and toxicity of unconjugated bilirubin and conjugated bilirubin
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unconjugated- relatively insoluble in the blood, but is too large to get filtered at the glomerulus. solubility increased by binding to albumin, but unbound acts like a lipid and can cross BBB.
Conjugated- totally harmless event neonates. water soluble, and never albumin bound. small enough to be filtered at the glomeruli of the nephrons and is eliminated in the urine |
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kernicterus
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Unbound unconjugated bilirubin can cross the BBB and is absorbed into the CNS neuron cell membranes forming a pathological inclusion that interferes with myelination
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Which types if bilirubin cause jaundice
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Unconjugated and conjugated!
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Normal ranges for bilirubin in adults and neonates
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Adult: total- 0.2-1.0 mg/dL
Direct- 0.0-0.4 Neonate- cord blood- less than 4.5 3-day less than 7.0 5- day less than 12.0 7-day less than 7.0 (all indirect) Critical total bilirubin neonate-6months above 20mg/dl |
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Explain the breakdown of hemoglobin to conjugated bilirubin and urobilinogen
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Hgb is broken down into bilirubin, iron, and blogin.
-bilirubin binds with albumin in the blood and then is acted on by blucuronyl transfer ease to make bilirubin diglucuronide(conjugated,direct) -conjugated bill is excreted into the intestinesand bacterial enzymes convert urobilinogen into urobilins - urobilinogens and urobilins are excreted in the feces at about 50-250 mg/day |
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How do we get indirect bilirubin form a bili assay
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Total-direct=indirect
Or Total-conjugated=unconjugated |
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Normal findings for urobilinogen and bilirubin in the urine
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Both should be negative
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Findings in pre-hepatic jaundice
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Total bilirubin- 3.6mg/dl
Direct bilirubin- 0.3 Elevation is due to uncojugated Urine urobilinogen- positive Urine bilirubinn- negative |
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What is pre-hepatic jaundice seen in?
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-normal neonatal physiological jaundice, gilberts, criggler-najjar
- hemolytic disease of the newborn - acanthocytosis - sickle cell or hemoglobinopathies - transfusion reactions |
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What is hepatocellular jaundice seen in
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Seen in any type of acute hepatitis, like hep A, B, C or chemical hepatitis
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Values seen in hepatocellular jaundice
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Total bilirubin- 4.2mg/dl
Direct bilirubin- 2.8 Elevation due to both conjugated and unconjugated Urine urobilinogen is positive Urine bilirubin is positive |
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What is hepatobiliary jaundice seen in? (post hepatic)
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Primary biliary atresia- rare pediatric disease
Gallbladder diaease- choleostasis- extra-hepatic bile stone in gallbladder or intra-hepatic bile stone within liver |
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Values seen in post hepatic jaundice
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Total bilirubin- 4.6mg/dl
Direct bilirubin- 4.2 Elevation due to conjugated bilirubin Urine urobilinogen is negative Urine bilirubin is positive |
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Explain gilberts syndrome and values
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- a physiological jaundice
- total bilirubin 2.6 Direct bilirubin- 0.3 Elevation due to indirect Urine urobilinogen is positive Urine bilirubin is negative |
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Explain criggler-najjar
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- usually a physiological jaundice
- total bill 2.6 - direct bill 4.2 Elevation due to indirect Urine urobilinogen positive Urine bili is negative |
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Explain dubin-Johnson syndrome and values
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An obstructive physiological jaundice
-total bili-4.6 Direct bili- 4.2 Elevation is cue to conjugated bili Urine urobilinogen is negative Urine bili is positive |
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Specimen of choice for bili assays
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Fresh unhemolyzed serum
-fresh unhemjolyzed heparinized plasma is an acceptable alternative |
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Specimen handling for bili assays
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Protect from light- light labile
Keep cool- heat labile Assay asap- degrades with time Hemolysis will cause increased values if read at a wavelength below 600nm |
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Methods for bili assays
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Nearly all analyzers use methods that are modifications of
Jendrassic Grof method Evelyn Malloy Method Both of these use a diazo reaction |
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Explain Evelyn-Malloy method
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- uses a diazo reagent
- fractionation by solubility in polar vs. Non polar solvent. - direct soluble in water - total measured in ethanol Rxn ended with red Azobilirubin and read below 600 |
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Explain Jendrassic-Groff method
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Uses a diazo reagent
- fractionation by solubility in pH - direct soluble in HCL pH 1.3 - total measured in Acetate-Caffiene reagent (pH 8.0, caffiene is also a catalyst - after Red Azobilirubin is formed fehling II reagent is added to shift the product to Blue Azobilirubin and read at 600nm - hemoglobin interference is minimized |
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Precaution on pediatric bili levels
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Dilute pediatric samples prior to analysis's appropriate to avoid redraws for more specimen.
- most analyzers have a linear range that is meant for adult values. Newborns can be 12-30 mg |
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Explain direct-reading bilirubinometers
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Bili is a yellow chromophore so the sum level in a newborn may be directly measured in a bilirubinometer.
The specimen is a diluted sum or plasma - a biggie for PCMC type hospitals - vitros are replacing the need for bilirubinometers |
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Explain vitreous bilirubin slides
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-uses two slides TBIL and BU/BC
- TBIL is a diazo rxn reading color using one wavelength - BU/BC is a diazo rxn but the color is read at two wavelengths since bu and bc have slightly different absorbing spectra |
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Explain vitros neonatal bilirubin assay
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TBIL slide is not FDA cleared for neonates under 3 weeks old and should not be used
- NBILI = total of BU and BC - DBILI = BC portion of slide usually is very small - during the first few days of life the neonate does not have any conjugated bili |
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Delta bilirubin
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It was noticed that the TBILI was greater than the total of BU+BC in neonates and than was noticed among adults
- this occurred in patients with hepatitis and choleostasis. - the difference between the TBILI and the BU/BC was called the difference or Delta bilirubin - delta bili represents unconjugated bili that has been covalently bound to Albumin |
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Ammonia
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-end product of protein and a amino acid catalbolism
- strongest naturally occurring base - if ammonia builds up in the system it causes metabolic alkalosis - very toxic to nereves causing shaking and spasms - liver is the only organ able to detoxify ammonia by converting it to urea which is completely harmless |
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Reference range for ammonia
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7-27 mol/L
- usually reported as mol/L Nitrogen - low levels are fine, but high will cause alkalosos |
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Ammonia specimen handling
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Specimen of choice is Heparinized plasma (green cap)
- keep in ice to slow enzymatic rxn and assay immediately - keep specimen tightly capped until you actually perform the assay. Ammonia is volatile and will evaporate |
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Ammonia and urea levels and disease correlation
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Elevated ammonia- hepatic disease
Low normal to decreased urea- hepatic disease |
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Normal values for plasma ammoia nitrogen
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7-27 umol/L
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Normal values for BUN and Urea
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BUN- 7-18 mg/dL
Urea- 15-38 mg/dL |
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Normal values for creatinine
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Serum/plasma
Males- 0.6-1.2 mg/dL Females- 0.5-1.1 24 hr creatinine Male- 800-1800 mg/day Female- 600-1600 |
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Normal values for creatinine clearance (GFR)
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Males- 97-137 mL/min/1.73m
Females- 88-128 |
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Normal values for uric acid
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Males 3.5-7.2 mg/dL
Females 2.6-6.0 |
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What is the conversion from bun to urea?
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BUN x 2.14= urea
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Azotemia
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Elevated blod levels of non protein waste products, like BUN creatitnine uric acid
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Uremia
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End stage renal failure,
Azotemia plus other signs and symptoms of renal failure |
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Pre renal azotemia
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Caused by Not perfusing the. Kidneys with blood, diet, and heavy metal poisoning
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Renal azotemia
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Caused by intrinsic damage to nephrons
- acute glomerulonephritis - interstitial nephritis - acute peel nephritis - acute tubular necrosis |
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Hallmarks of acute glomerulonephritis
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Prorenturia with tons of rbc and rbc casts
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Hallmarks of pyelonephritis
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WBC's, WBC casts, bacteria, and epithelial cells
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Post renal azotemia
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Caused by urethral obstruction, and kidney stones
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Correlation between intra renal disease and creatinine levels
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Each 0.1 mg/dl increase in serum creatinine corresponds to a 5-7% function loss
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Pre renal azotemia BUN/creatinine ratios
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>24
caused by shock, not perfusing the kidneys with blood |
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Intra renal azotemia BUN/creatinine ratios
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<15
caused by damaged nepnrons |
