9 Body fluids

Cerebrospinal Fluid

• surrounds brain and spinal cord

• from subarachnoid space

Function

• Physical protection/cushion brain

• supply nutrients / remove waste

• Transport

Lumber tap (collection order, reason for collection)

• 3~4 tubes from L3 or L4 below

Remember from Heme: Tube allocation order by department

1. Chem

2. Micro

3. Heme

4. Extra

Reasons

• CNS infection

• demyelinating disease

• malignancy

• CNS hemmorrage

Cerebrospinal Fluid

• surrounds brain and spinal cord

• from subarachnoid space

Function

• Physical protection/cushion brain

• supply nutrients / remove waste

• Transport

Lumber tap (collection order, reason for collection)

• 3~4 tubes from L3 or L4 below

Remember from Heme: Tube allocation order by department

1. Chem

2. Micro

3. Heme

4. Extra

Reasons

• CNS infection

• demyelinating disease

• malignancy

• CNS hemmorrage

Characteristics of CSF

Color

• red - hemorrhage or traumatic tap

  • always spin red CSF and check if the supernatant is xanthochromic (yellow)

  • checks how long it has been since the bleed

Clarity

• turbid = infection?

Clot/hemosiderin-containing macrophages

Biomarkers for CSF (4)

• Glucose

• Protein

• Lactate

• Glutamate

CSF Glucose

• CSF Glucose 2/3 (60-70%) of Plasma Glucose, until plasma glucose reaches >600 mg/dL

• High CSF glucose not clinically significant

• LOW CSF Glucose

  • glucose transport carrier disorder

  • increased metabolism by organism or cells (bacteria, tumor)

  • Increased lactate if glucose consumption increased

CSF Protein

• 0.5~1% of plasma total protein, fractional concentration NOT proportional to plasma protein

  • Must be compared to plasma protein

• Decreased protein

  • Decrease inflow from plasma

  • Increased protein loss

  • Leakage in dura (tears from traumatic tap), ear, or nose (runny nose)

  • Detect leakage by testing for beta-transferrin (protein only in CSF)

• Increased protein

  • clinically nonspecific

  • contamination from traumatic tap (plasma protein)

  • increased permeability of BBB (blood brain barrier) can be caused from bacterial/fungal infection

    • not diagnostic

  • Increased CNS protein production

Albumin and IgG in CSF

Albumin

• produced in liver, not too much should be in csf

IgG

• can be produced locally in CNS by plasma cells

CSF serum albumin index

(CSF albumin mg/dL)/(Serum albumin mg/dL)

Index value <9 intact BBB

Index vaule >9 damaged BBB

CSF IgG Index

CSF IgG/Serum IgG

Normal Index <0.73

Increase IgG index w/ no increase in albumin suggests local igG synthesis

• MS or SSPE

Increase IgG index and albumin

• Bacterial meningitis

CSF electrophoresis

Ran when etiology is unclear, normal CSF protein but show inflammation

Oligoclonal bands: multiple banding in the gamma region, usually seen with MS or SSPE

Lactate CSF

• Indicator of anaerobic metabolism

• Increased lactate, decreased glucose —> bacterial meningitis

• Time-sensitive, collect in sodium fluoride tube

Glutamine CSF

• ammonia + glutamate

  • ammonia test w/ in 30min

• correlation of ammonia level in CNS

• Increase in hepatic encephalopathy

Serous Membranes (2)

• parietal membrane line cavity wall

• visceral membrane line organ

Surrounds heart, lung, abdomin

Serous fluid (3 types and formation)

• Pleural—lung

• Pericardial—heart

• Peritoneal--abdominal

Continuously formed, and circulated by hydrostatic pressure and oncotic pressure

• ultrafiltrate of plasma

• arterial capillaries - fluid moves out to interstitial space

• Venous capillaries - fluid moves into capillaries from interstitial space

• Lymphatics - excess fluid from interstitial space flows here

Effusion

Accumulation of serous fluid

Transudate

Effusion that occurs during various systemic disorders that disrupt fluid filtration, fluid reabsorption, or both

• Congestive heart failure, hepatic cirrhosis, nephrotic syndrome

Exudate

Effusion that occurs during inflammatory processes that result in damage to blood vessel walls, body cavity membrane damage, or decreased reabsorption by the lymphatic system

• Infections, inflammations, hemorrhages, malignancies

Differentiate exudate and transudate by testing for

Fluid appearance, specific gravity, amylase, glucose, lactate dehydrogenase (LD), proteins, ammonia, lipids, pH

Pleural Fluid

Enter as ultrafiltrate of plasma through parietal layer and exit through lymphatics of visceral layer

• inner layer (visceral) - bronchial circulation

• outer layer (parietal) - systemic circulation

Normal: 3-20mL

Thoracentesis

• pleural (lung) fluid removal through chest

• anticoagulant tubes

Pleural Transudate

Secondary to remote (non-pleural) systemic pathology

Have biochemical and cellular abnormalities consistent non-inflammatory changes in fluid dynamics

Ex: hypoproteinemia due to malnutrition—leads to decreased osmotic pressure and decrease in fluid resorption into the capillaries

Causes:

• congestive heart failure ****most common

• nephrotic syndrome

• hypoproteinemia

• hepatic cirrhosis

• chronic renal failure

Pleural exudate

Primary involvement of the pleura and lung (ex. Infection)

Requires immediate attention

Ex: infection-mediated damage to the membranes allowing increased fluid entry into the pleural space

Causes

• bacterial pneumonia ****

• tuberculosis

• pulmonary abscess

• malignancy causing lymphatic obstruction

• viral/fungal infection

• lymphoma

Pleural transudate Lights criteria (PF/Serum protein and LD ratio and PF LD)

• PF/Serum protein <0.5

• PF/Serum Lactate dehydrogenase (LD) <0.6

• PF LD <2/3URL

Pleural exudate Lights criteria (PF/Serum protein and LD ratio and PF LD)

• PF/Serum protein >=0.5

• PF/Serum Lactate dehydrogenase (LD) >=0.6

• PF LD >=2/3URL

Pleural fluid other tests

• Fluid cholesterol

  • Exudates cholesterol >60 mg/dL

• Fluid to serum cholesterol ratio

  • Exudates ratio >0.3

• Fluid to serum bilirubin ratio

  • Exudates ratio ≥0.6

• Further characterization

  • Glucose, lactate, amylase, triglyceride, pH, or uric acid

• Inflammation: decreased glucose or increased lactate

• Pancreatitis: increased amylase

• Triglyceride: (grossly elevated 2-10x serum levels) thoracic duct leakage

• pH: <7.2 infection; close to 6.0 esophageal rupture

• Uric acid: levels significantly lower in exudates

Pericardial fluid

• Normal <50mL

• effusions almost always exudate and caused by damage to mesothelium

• pericardiocenthesis - procedure is dangerous to perform, rare

Pericardiocentesis

• needle inserted through chest with electrocardiographic monitoring to find heart

• DANGEROUS

Peritoneal Fluid

AKA ascitic fluid

abdomen

paracenthesis

Ascites

excess peritoneal fluid

>50mL indicate disease

peritoneal transudate

• secondary pathology

• most common - portal hypertension

Peritoneal exudate

• primary pathology

• metastatic ovarian, prostate, colon cancers OR infective peritonitis

  • PMN>250 cells/um in infective peritonitis

Serum ascite albumin gradient (SAAG)

SAAG = serum albumin - ascitic albumin

> 1.1 g/dL Transudate

<1.1 g/dL Exudate

Amniotic fluid source

Maternal plasma and later, mostly fetal urine

• controlled by fetal swallowing of fluid

• Fetal skin also permeable to fluid, becomes less permeable as gestation goes on

Extracting amniotic fluid

amniocentesis

• ultra sound guided

• used to test for hemolytic disease of new born, neural tube defect, fetal lung development

Hemolytic disease of new born

caused by maternal antibody against fetal RBC. bilirubin in amniotic fluid

Neural tube defects

Test for alpha-fetoprotein and compare multiple median

1. test maternal plasma

2. test again if high

3. ultrasound

4. amniocentesis

Fetal lung maturity

Main reason for amniocentesis

• phosphatidylglycerol and lectin-sphingomyelin checked

  • PG increased proportionally to L/S

• Lamellar body checked

  • phospholipid produced by type II alveolar cells

  • run on heme analyzer bc size similar to PLT

Lamellar body count of mature lung

>50,000/uL

Lamellar body count of immature lung

<15,000/uL

Synovial fluid sample collection and prep

arthrocentesis, treat with hyaluronidase

Synovial fluid total protein

• normal 1-3g/L

• increased in arthritis, gout, ulcerative colitis, ankylosing spondylitis

Synovial fluid glucose

• 10 mg/dL lower than serum glucose

• decreased ratio suggest inflammation or infection

Synovial fluid uritic acid

GOUT

Synovial fluid lactic acid

septic arthritis

Normal synovial fluid

• colorless

• high viscosity

• mucin clot good

• <150 WBC <25% PMN

• Glucose blood:SF 0-10

Non inflammatory synovial fluid

• yellow, slightly cloudy

• decreased viscosity

• mucin clot fair

• <1000 WBC <35% PMN

• Glucose blood:SF 0-10

Inflammatory synovial fluid

• white, yellow, grey, turbid

• no viscosity

• mucin clot poor

• <100,000 WBC >50% PMN

• Glucose blood:SF 0-4

Septic synovial fluid

• white, yellow, grey, cloudy

• no viscosity

• mucin clot poor

• 50,000-200,000 WBC >90% PMN

• Glucose blood:SF 20-100

• cultures positive

Crystal induced synovial fluid

• white, cloudy, milky

• no viscosity

• mucin clot poor

• 50,000-200,000 WBC <90% PMN

• Glucose blood:SF 0-80

• crystals present

Hemorrhagic synovial fluid

• red, brown, xanthochromic, cloudy

• no viscosity

• mucin clot poor

• 50-10,000 WBC <50% PMN

• Glucose blood:SF 0-20

• RBC present

Sweat

Only tested for cystic fibrosis using sweat chloride test

• autosomal recessive disorder that affects exocrine glands and causes electrolyte and mucus secretion abnormalities

• >60 mmol/L is a positive test