Body fluids, Their Importance, and Risk of Infections

Body fluids

Distribution of total body fluids

• The sum of fluids within all body compartments comprises total body water is about 60% of the body weight.
• It is 60% in males and 50% in females, while in infants is 70% of the total body weight.

Total Body Water as the percentage of body weight

The body  fluids are distributed in various compartments of the body:

1. Intracellular fluid:
   1. It is 40% of the total body weight, around 28 liters.
2. Extracellular fluid:
   1. It is 20% of the total body weight, around 14 liters.
      1. This fluid may be interstitial = 15% of total body weight (11 liters).
      2. This may be intravascular = 5% of total body weight (3 liters).
   2. Total body water = 60% of the total body weight (42 liters).
3. At birth, total body water is 75% to 80% of the body weight. It decreases to about 67% during the first year of the baby.
4. In adolescence, total body water is around 60% to 65% of total body weight.
5. Males have more total body water due to increased muscle mass, and females have less due to body fats.

Body water distribution

Water movement between intracellular fluid (ICF) and Extracellular fluid (ECF):

1. Potassium (K⁺) maintains the intracellular fluid (ICF) osmotic balance.
2. Sodium (Na+) maintains the extracellular fluid (ECF) osmotic balance.

Total body water osmotic balance

The distribution of body fluids:

1. Blood.
2. Bloody fluids.
3. Pleural fluid.
4. Pericardial fluid.
5. Peritoneal fluid (ascites).
6. Amniotic fluid.
7. Cerebrospinal fluid.
8. Semen.
9. Urine.
10. Vaginal secretions.
11. Saliva is a dental procedure.
12. Synovial fluid.
13. Pus and purulent discharge.
14. Tissue biopsy or organ which is unfixed.

Body fluids from various sites

Risk and Route of infections:

1. Many body fluids, including blood, are infectious and hazardous materials for human beings, particularly people working in the laboratory.
2. These biological hazards expose unprotected laboratory workers to bacteria, viruses, parasites, and other biological agents.
3. This infection may be from ingestion, inhalation, inoculation, or tactile contact. The infectious material may be inhaled from the patient or their body fluids/tissues.

The source of contamination may be from:

1. Contaminated laboratory equipment.
2. Improperly processed blood products.
3. Inappropriate disposal of laboratory waste products.

Noninfectious material is:

1. Sputum.
2. Saliva.
3. Nasal secretion.
4. Sweat.
5. Stool.
6. Tears.
7. Urine.

Importance of various body fluids:

Saliva:

1. Salivary glands produce almost one liter of fluid /day, serous and mucinous material.
2. Some drugs that can be monitored include Digoxin, Phenytoin, Theophylline, Phenobarbitol, dexamethasone, benzodiazepine, cocaine, heroin, codeine, and nicotine.
3. Drug abuse like alcohol, barbiturates, amphetamines, and marijuana can also be monitored.
4. The hormones like progesterone, 17-alpha-hydroxyprogesterone, cortisol, DHEA, Androstenedione, and testosterone can also be measured.
5. Sjogren’s syndrome can be diagnosed by measuring increased Na⁺ and chloride.
6. Radioactive material is measured for the diagnosis of Hyperthyroidism and hypothyroidism.
7. Can diagnose cystic fibrosis.
8. Can estimate secretory IgA.
9. Take care of saliva contamination by blood due to chewing or flossing.

Nasal secretions:

1. It helps to diagnose allergies by showing an increased number of eosinophils.
2. An increased number of polys indicates acute infection.
3. Increased eosinophils and neutrophils indicate infection superimposed on chronic allergy.
4. Can detect RSV by rapid antigen test.
5. It will differentiate between nasal secretions and CSF in a possible skull fracture.

Sputum:

1. The usefulness of the sputum culture is controversial.
2. Mostly the sputum is contaminated by upper respiratory tract bacteria.
   1. Some contaminants are staphylococcus aureus, streptococcus pneumonia, Hemophilus influenza, enteric gram-negative organisms, and candida.
3. In literature, there is a dispute that sputum culture may find the causative agent.
4. In case a pure growth of the organism is found to favor the pathogenic infection.
5. In case of increased squamous cells, favor the contamination by oropharyngeal mucosa.
   1. Squamous epithelial cells >19/LPF = poor specimen.
   2. Squamous epithelial cells 11 to 19/LPF = Fair specimen
   3. Squamous epithelial cells <10/LPF = Good specimen.
6. The more squamous epithelial cells are found, the more chances for contamination.
7. Sputum can be used for cytological studies to rule out malignancy.
8. Sputum can diagnose various diseases:

Tears:

1. Tears may decrease in Sjogren syndrome, dehydration, decreased facial nerve function, and Horner syndrome.
2. Lysosomal diseases may be diagnosed by the deficiency of enzymes in the tears. The following diseases are diagnosed:
   1. Tay-Sachs disease.
   2. Fucosidosis.
   3. Type II glycogenesis.
   4. Metachromatic leukodystrophy.
   5. Fabry disease.
   6. Sandhoff disease.
   7. Mannosidosis.
   8. Hurler and Scheie syndrome.
   9. Gm₁-gangliosidosis.
3. Decreased volume is also seen in dehydration.

Milk:

1. If there are increased WBCs in the milk, that will indicate acute infection.
2. >10³ colonies of the bacteria/mL  (WBC >10⁶) indicate infections compared to the noninfectious inflammation or clogged ducts.
   1. It is usually due to S. aureus or S. epidermidis (penicillin-resistant).
   2. This infection develops in nursing mothers (∼2.5%), usually 2 to 5 weeks after postpartum.

Cerebrospinal fluid (CSF):

1. CSF may be the cause of bacterial or viral meningitis.
2. Infants under 1 to 2 months have the most common infection by B streptococci.
   1. Children from 3 years to 5 or 6 years have H. Influenzae commonest organism, followed by meningococci and pneumococci.
3. Children and older adults have meningococcal meningitis; the second common organism is pneumococci.
4. In older people, pneumococci are more common than meningococci.
5. CNS syphilis can also be seen and diagnosed through CSF examination.
6. Mycobacterial meningitis is common in children between 6 months and 5 years old. It is also seen in elderly patients.
7. Cryptococcal meningitis is the most common fungus-producing CNS infection. Other fungi causing CNS infections are Candida, blastomycosis, histoplasmosis, and coccidioidomycosis.
8. HIV also produces mild aseptic meningitis.

Semen:

1. There may be infection by chlamydia and syphilis.
2. The presence of inflammatory cells indicates genitourinary infections.
3. The most common organisms are E.coli.
4. Viruses can also live in the semen, like Ebola, HIV, hepatitis B, HCV, and herpes.
5. Chronic infections affect the sperm count and lead to infertility.

Vaginal secretions:

1. Trichomonas causing vaginitis is quite common. Freshly prepared PAP smear sensitivity is 50% to 70%.
2. Bacterial infection of the vagina may be due to aerobic and anaerobic organisms.
3. There may be an infection from G. vaginalis and Mobilucus accompanied by lactobacillus.
4. Local causes may be endocrine, poor hygiene, scabies, pinworms, foreign bodies, and local irritants.
5. There may be infection by the N. gonorrhea, Chlamydia, streptococcus group A,  staphylococcus aureus, and idiopathic associated with HIV.

Synovial fluid:

1. Nearly 1 mL of the synovial is aspirated for the culture and other studies.
2. Gram stain reported 40% to 70% positive in septic arthritis.
3. Gram-positive organisms are more common than gram-negative bacteria.
4. Gonococcal infection is the most common cause.
5. Occasionally synovial RA test is positive before the serum.
6. Lactate is raised in septic arthritis and is >250 mg/dL.
7. Complement is lowered in rheumatoid arthritis and SLE.

Sweat:

1. This is important for the diagnosis of various diseases.
2. There is a change in the electrolytes in cystic fibrosis.
3. Various diseases have different odor, like maple syrup and some drugs.
4. Sweat color is also important in various diseases like brown in ochronosis, red in rifampin (overdose), and blue in occupational exposure to copper.

Stool:

1. Stool examination is one of the noninvasive procedures to diagnose various diseases.
2. The stool can be cultured to diagnose bacterial diseases like salmonella, shigella, and tuberculosis.
3. A stool examination can be done to diagnose parasitic infestation.
4. A stool examination can diagnose viral diseases.

Urine:

1. The urinary tract infection (UTI) most common organism is E.coli.
2. Nitrite test dispositive in UTI.
3. Nitrite-negative organisms are enterococci, N.gonorrhea, and M. tuberculosis.

Pathological fluids:

Ascites:

Ascites may be seen in:

1. Chronic liver disease = 81%
2. Malignancies = 10%
3. Congestive heart failure = 3%.
4. Tuberculous ascites = 1.7%.
5. Patients with dialysis = 1.0%.
6. Gram stain of the ascitic fluid shows few bacteria by spontaneous peritonitis, but many are due to intestinal perforation.
7. This may be seen in tuberculosis and gram-negative bacteria like Klebsiella, E.coli, and other gram-negative bacteria.
   1. Gram-positive bacteria, especially streptococci, may see this.

Pleural effusion:

1. The most common cause of pleural effusion is congestive heart failure and malignancies.
2. Infections like tuberculosis and pneumonia are the third most common causes.
3. Try to differentiate the chylous effusion, usually due to increased triglycerides.
4. Pleural fluid CEA levels may increase in various malignancies and benign conditions.

Pericardial effusion:

1. Pericardial effusion may develop due to active rheumatic fever in 40% of the cases.
2. Bacterial infection leading to pericardial effusion is due to tuberculosis, streptococcus pneumonia, staphylococcal, and gram-negative bacilli.
3. Other infections may be due to Coxsackie B, rickettsial parasites, mycobacteria, and fungi.
4. The most common cause is viruses.
5. Rarely this may develop into severe anemia, scleroderma, polyarteritis nodosa, Wegener granulomatosis, rheumatoid arthritis, radiation, mycotic infections, and idiopathic.

Ear discharge:

1. Ear discharge is also called otorrhea.
2. A middle ear infection may be bacterial or viral.
3. Ear discharge may be seen in the ruptured eardrum.
4. Other causes of ear discharge are swimming, foreign objects, wax, and trauma.

Questions and answers: