Body Fluids Flashcards
CSF
Flows where?
Functions?
- Flows in subarachnoid space
- Functions to give physical support/protection, controlled chem environment to supply nutrients/remove wastes, and transport
Lumbar puncture area and tube order
- L3/L4
1. Chemistry/Serology
2. Microbiology
3. Hematology
4. Extra/cytology
Why investigate CSF?
- Infection
- Demyelinating disease
- Malignancy
- Hemorrhage into CNS
What color is xanthrochromic CSF and why is it that color?
Yellow due to bilirubin from RBC breakdown in old hemorrhage
T/F: CSF from fresh hemorrhage tends to clot
False
CSF from traumatic tap (decreasing amounts of redness in each successive tube) tends to clot
4 main markers in CSF
- Glucose
- Protein (total/specific)
- Lactate
- Glutamine
How to prep CSF specimen for analysis
Always centrifuge even if clear/colorless!
Glucose in CSF
CSF transport
When to collect
Conc in CSF
- Enters CSF through facilitative protein transport
- Collect blood glucose 2-4 hrs prior
- CSF glucose conc 60-70% of plasma glucose (but no longer applies once >600 mg/dL)
Hypoglycorrhachia
Decreased CSF glucose levels
Causes of hypoglycorrhachia + examples
- Disorder in carrier-mediated transport of glucose into CSF
- Active metabolism of glucose by cells/organisms
- Increased metabolism by CNS
- Examples: meningitis, meningeal neoplasia, brain tumor
Consumption of glucose usually has increased _____ level due to ______ glycolysis by organisms or tissue
Lactate
anaerobic
What do CSF protein levels reflect?
Selective ultrafiltration of CSF blood-brain barrier
Total protein conc in CSF
0.5%-1.0% of plasma
Not proportional due to specificity of ultrafiltration process
Which analysis should accompany CSF protein analysis?
Serum
Causes of decreased protein CSF
- Decreased dialysis of proteins from plasma
- Increased protein loss (removal of excessive volumes of CSF)
- Leakage from a tear in the dura, CSF otorrhea (ear), or CSF rhinorrhea (nose)
How to detect CSF leakage
Analysis of beta-transferrin bc it’s unique to CSF
Causes of increased protein in CSF
- Lysis of contaminant blood from traumatic tap
- Increased permeability of epithelial membrane
- Increased production by CNS tissue obstruction
How do bacterial/fungal infections affect the BBB?
Increase permeability
T/F: Protein in CSF is NOT diagnostic of infectious meningitis - helpful though
True
Normal CSF and serum prealbumin conc. Why is it measured in both?
- CSF > serum conc
- Used to normalize IgG values to determine source
Describe proteins of highest interest in CSF
- Albumin: must cross BBB
- IgG: Can be produced by local synthesis from plasma cells within the CSF
Index value of protein which indicates intact BBB
protein index < 9
IgG index
How to calculate
What does it help diagnose
Normal value
- Use CSF serum index
- Helps diagnose demyelinating diseases (MS, SSPE)
- Normal IgG < 0.73
How does serum albumin affect CSF levels?
Increases CSF levels due to membrane permeability
What does increased CSF IgG without concomitant CSF albumin suggest?
Local production (MS/SSPE)
How does bacterial meningitis affect membrane permeability and protein production?
Increases both
When to perform CSF protein electrophoresis?
- When CSF protein is elevated without clear etiology
- Normal CSF protein in pts with inflammatory disease symptoms
Oligoclonal bands
- Multiple banding in gamma region, involves small number of IgG clones
- Presence of oligoclonal bands supersedes the report of normal protein levels
- Usually seen with MS or SSPE
Lactate CSF marker
Useful indicator of what?
Collect in which tube?
- Indicator of anaerobic metabolism
- Sodium fluoride tube bc time critical
Glutamine
Formation
Correlate to…
Elevated in pts with ___
- Ammonia + glutamate -> glutamine
- Ammonia not stable for testing but glutamine levels correlate to ammonia in CNS
- Hepatic encephalopathy
Serous fluids
Parietal membrane
Visceral membrane
Definition
- Parietal membrane = lines cavity wall
- Visceral membrane = line organs
- Def: ultrafiltrate of plasma
Pleural
Pericardial
Peritoneal
- Lung
- Heart
- Abdominal
Effusion
Accumulation of serous fluid
Transudate
- Occurs during various system disorders that disrupt fluid filtration, fluid reabsorption, or both
- Congestive heart failure, hepatic cirrhosis, nephrotic syndrome
Exudate
- Occurs during inflammatory processes that result in damage to blood vessel walls, body cavity membrane damage, or decreased reabsorption by the lymphatic system
- Infections, inflammation, hemorrhages, malignancies
Tests used to differentiate btwn transudate and exudate
- Fluid appearance
- Specific gravity
- Amylase
- Glucose
- Lactate dehydrogenase
- Proteins
- Ammonia
- Lipids
- pH
Pleural fluid
Location
How formed?
Volume
Exits how
- Outer layer of pleural space (systemic circulation) and inner (visceral) layer for bronchial circulation
- Ultrafiltrate of plasma
- 3-20 ml
- Drains into lymphatics of visceral pleura and visceral circulation
Thoracentesis
Removal of pleural fluid (from thorax)
Pleural fluid transudates
- Secondary to non-pleural pathology
- Biochem/cellular abnormalities consistent with non-inflammatory changes in fluid dynamics
- E.g., hypoproteinemia due to malnutrition -> reduced osmotic pressure, reduced fluid resorption in capillaries
Pleural fluid exudates
- Primary involvement of the pleura and lung (infection)
- Immediate attention required
- E.g., infection-mediated damage to membranes allowing increased fluid entry into pleural space
How did transudates/exudates used to be determined? What do we use now?
- Used to be based on protein concentration
- Now use Light’s criteria
Pleural fluid
Cholesterol
Fluid to serum cholesterol ratio
Fluid to serum bilirubin ratio
Further characterization
- Exudate chol > 60 mg/dL
- Exudates ratio >= 0.3
- Exudates ratio >= 0.6
- Glucose, lactate, amylase, triglyceride, pH, uric acid
Pleural fluid lab findings
Inflammation
Pancreatitis
Triglyceride
pH
Uric acid
- Inflammation: reduced glucose or increased lactate
- Pancreatitis: increased amylase
- Triglyceride: 2-10X serum levels, thoracic duct leakage
- pH <= 7.2 means infection
pH close to 6.0 means esophageal rupture - Uric acid: significantly lower in exudates than transudates
Pericardial fluid
Causes of pericardial effusions
Transudate/exudate categorization
Volume
Pericardiocentesis done when?
- Causes: damage to mesothelium
- Almost always exudates
- Normally fluid < 50 ml
- Dangerous procedure, rarely performed. Do only if cultures needed for infection or cytology for sus malignancy
Peritoneal fluid
Indicator of disease?
Excess fluid terminology
Fluid visualized by ____
- Fluid > 50 ml indicates disease
- Ascites
- Ultrasound
Peritoneal fluid
Cause of exudate
Cause of transudate
WBC
- Primary pathology (metastatic ovarian, prostate, or colon cancer, infective peritonitis)
- Secondary pathology (portal hyper tension most common)
- PMNs < 250 cells/um: peritonitis
How to differentiate causes of peritoneal fluid issues
- Serum-ascites albumin gradient (SAAG)
- (Serum albumin ) - (fluid albumin) = SAAG
- Difference >= 1.1 g/dL means transudative
- Difference < 1.1 g/dL means exudative
Amniotic fluid
Function
Sources
Continuous contact with ___
- Functions to cushion fetus, regulate temp, allow fetal movement, matrix for influx of glucose/sodium/potassium, fetal urination/swallowing balance
- Sources: mother, mainly by transudation across fetal skin; last half of pregnancy fetal urination major volume source bc skin less permeable
- Fetal GI tract, buccal cavity, lungs
Amniocentesis
- Amniotic sac puncture
- Done less bc can get baby DNA from mom’s blood
- Ultrasound guided
- Analyze for: congenital diseases, neural tube defects, HDN, fetal pulmonary dev
- Mainly done to assess fetal lung maturity
Hemolytic disease of the newborn (HDN)
Definition
Sample handling
- Definition: syndrome of fetus resulting from incompatibility between maternal and fetal blood (Rh- mom, Rh+ baby). Maternal Ab to fetal RBCs cause Hgb breakdown and bilirubin may appear in amniotic fluid
- Sample centrifuged fast and protected from light
Neural tube defects
Screen initially done for __
Calculate using ___
- Screen maternal serum for alpha-fetoprotein (AFP)
- Calculate using multiple of median (MoM)
Fetal lung maturity
Definition
Lipid content as lungs mature
Quant tests
- Definition: Determine if sufficient specific phospholipids are present to prevent alveolar collapse if fetus was delivered
- As lungs mature, see phospholipid increase (PG and lecithin)
- Quant tests: L/S ratio (2.0 breakpoint), PG, and lamellar body counts
What is given to the mother to enhance fetal surfactant production?
Steroids
PG test in AF
- PG must be performed along with L/S ratio
- PG increases proportionally with lecithin
- Diabetic moms: dev of PG delayed
Lamellar body counts in AF
- Phospholipids secreted by type II alveolar cells
- Lamellated packets of surfactant conc can predict fetal lung maturity
Sweat
Clinical use
Conc considered positive for disease
How is it measured?
Affected by ___
- Cystic fibrosis (autosomal recessive, electrolyte/mucus secretion abnormalities)
- Chloride > 60 mmol/L
- Measure chloride levels in sweat mixed with DI water
- Affected by hydration levels
Synovial fluid
Formation
Synovial membrane secretes ____
Function
Volume
Sample prep
- Formed as ultrafiltration of plasma across synovial membrane
- Mucoprotein-rich hyaluronic acid gives viscosity
- Functions as join lubricant and transport medium for delivery of nutrients and removal of cell wastes
- Vol <= 3 ml
- Add hyaluronidase to break down mucoprotein matrix
Synovial fluid
Chemical analysis
Normal range
Synovial: serum glucose ratio
- Total protein (TP), glucose, uric acid, LD
- TP 1-3 g/dL
- 0.9:1.0 normal best way to eval glucose levels
Decreased ratio: inflammation and sepsis
Uric acid normal range
6-8 mg/dL
Lactic acid normal range and septic arthritis amounts
- Normal < 25 mg/dL
- Septic arthritis up to 1000 mg/dL
