Blood Chloride (Cl^–)

What sample is needed for Blood Chloride Cl¯?

1. It is performed on the patient’s serum or plasma.
2. Except in emergencies, collect fasting samples because there is a slight decrease in blood sugar levels after meals.
3. Chloride is estimated in sweat to rule out cystic fibrosis.
4. Other samples are CSF and 24 hours of urine.

What are the Indications for Blood chloride?

1. As a part of electrolytes, the acid-base balance.
   1. It gives status for hydration.
2. For the diagnosis of cystic fibrosis.

What are the precautions for Blood Chloride (Cl^–)?

1. Separate serum or plasma from the cells, as a change in pH will alter the distribution of Chloride.
2. Avoid hemolysis.
3. Serum, plasma, and urine are stable for one week at temperatures ranging from 1 to 4 °C or at room temperature.
4. A frozen sample can be stored for up to one year.
5. Drugs that may increase the chloride level are ammonium chloride, acetazolamide, cortisones, androgens, and estrogens.
6. Drugs that may decrease the chloride level are aldosterone, corticosteroids, thiazide diuretics, and loop diuretics.

How will you define blood chloride (Cl^–)?

1. Chloride is the most abundant extracellular anion.
2. The same conditions affect chloride, which affects sodium (the most abundant extracellular cation).

How will you discuss the pathophysiology of  Blood Chloride (Cl^–)?

1. Chloride is the most abundant extracellular anion.
2. Chloride is the major negative electrolyte(anion) in the extracellular fluid.
   1. Chloride with sodium represents the majority of the osmotically active constituents of plasma. Thus, the serum chloride level changes in the same direction as the sodium level, except for a few conditions. If the serum sodium level is low, then the serum chloride level will also be low.
3. The interstitial plasma fluid contains 103 mmol/L of chloride anions.
4. Its intracellular fluid (RBC) concentration is 45 to 54 mmol/L.
5. While the intracellular fluid of other tissues is only 1 mmol/L.
6. Most physicians advise “electrolytes panel or profile,” which includes:
   1. Sodium.
   2. Potassium.
   3. Chloride.
   4. Bicarbonate.

What are the extracellular and intracellular electrolytes?

How will you discuss the distribution of electrolytes?

How will you discuss the Chloride absorption and excretion?

1. Chloride ions in the food are absorbed entirely in the intestine.
   1. They are filtered from the plasma at the glomerular level and passively reabsorbed, along with Na⁺ in the proximal tubules.
2. Chloride interacts with sodium to maintain the osmotic pressure of blood.
3. Its main purpose is to maintain the electrical neutrality of salt by balancing the with sodium content.
4. Aldosterone increases the reabsorption of sodium and Chloride to maintain neutrality.
5. Chloride acts as a buffer to help in acid-base balance.
6. The concentration of Cl^– changes inversely with the changes in the concentration of HCO₃^–.

7. Chloride is filtered at the glomerulus passively and reabsorbed at the proximal tubules. Further absorption at the loop of Henle.
   1. There is a chloride pump in the ascending limb of the loop of Henle.
   2. Sodium is absorbed passively, while Chloride is absorbed actively by the pump.
   3. Excess Chloride is excreted in the urine and sweat.

What are the functions of Blood Chloride (Cl^–)?

1. Maintenance of water balance and osmotic pressure with the help of sodium.
2. Chloride moves into cells in exchange for bicarbonate produced in the cells.
3. It can maintain electrical neutrality.
4. It helps as a buffer to help in the acid-base balance.
5. Anion-cation balance in the extracellular fluid compartment.
6. Chloride provides electroneutrality, particularly with Na⁺.

What is the normal level of Blood Chloride (Cl^–)?

Source 1

1. Serum = 95 to 105 meq / L (98 to 106 mmol/L)
2. Urine = 110 to 250 meq/ 24 hours
3. Sweat:
   1. Normal = 5 to 40 meq/L
   2. Marginal value =  30 to 70 meq/L
   3. Cystic fibrosis = 60 to 200 meq/L
4. CSF:
   1. Infant  = 110 to 130 meq/L
   2. Adult  =  118 to 132 meq/L
      1. These are 15% higher than those in serum.
5. Saliva without stimulation  =  5 to 20 meq/L

Other Sources 

Cystic fibrosis:

How will you define cystic fibrosis?

1. Cystic fibrosis (mucoviscidosis) or fibrocystic disease of the pancreas is the most common lethal autosomal recessive. an inherited disorder in Europe.
2. In Europe, it is estimated that 1 in 2,000 live births.
3. In Afro-Americans, the incidence is 2% of that in Europe.
4. It is rare in Asians.

How will you discuss the pathology of cystic fibrosis?

1. Approximately 90% of homozygotes exhibit symptoms predominantly caused by damage to mucus-producing glands.
2. Non-mucus-producing glands may also be affected.
3. The mucus is very thick, which can plug the ducts and lead to obstructive complications.
4. In the lungs, it leads to recurrent bronchopneumonia. This is a very serious complication.
5. Pseudomonas and Staphylococcus aureus are the common pathogens.

What are the complications of Cystic fibrosis?

1. The next complication is the complete or partial destruction of the exocrine portion of the pancreas, and this will end up in various conditions, such as:
   1. Malabsorption.
   2. Steatorrhea.
   3. Digestive disturbances.
   4. Malnutrition.
2. A less common complication is biliary cirrhosis.

How will you perform the Sweat test for cystic fibrosis?

Procedure to collect the sweat:

1. Sweat is collected in a plastic bag or by iontophoresis.
2. Sweat-stimulating agents, such as pilocarpine, stimulate sweat production.
3. Iontophoresis involves the use of two small electrodes that generate a tiny electric current.
4. Sweat is collected in the small gauze pad.
5. This procedure is painless.

How will you interpret the Sweat test?

1. The levels of sodium and chloride are higher in patients with cystic fibrosis.
2. For a definite diagnosis, sweat is collected. The sample should weigh >50 mg, and weighing <50 mg is inadequate.
3. In children, sweat sodium levels greater than 70 meq/L and chloride levels greater than 60 meq/L are abnormal and diagnostic of cystic fibrosis.
4. Sodium and chloride levels may be elevated in the first three days of life and then decrease to childhood levels by the fourth day.
5. The sample should not be collected from the palm as there is an increased concentration of sodium and chloride (electrolytes).

What are the signs and symptoms of Hypochloremia?

1. There is a loss of Cl-, usually resulting from hyponatremia or an elevated HCO3- concentration, as seen in metabolic alkalosis.
   1. This will develop with vomiting and loss of HCL.
   2. Hypochloremia characterizes cystic fibrosis.
   3. A Cl- deficiency accompanies the restricted use of salt or the use of diuretics.
2. There is hyperstimulation of the nervous system and muscles.
3. Shallow breathing.
4. Hypotension.
5. Tetany.

What are the signs and symptoms of Hyperchloremia?

1. This occurs when there is too much sodium or too little bicarbonate.
2. A significantly higher amount of Cl^– , can be expected with hypernatremia or metabolic acidosis.
3. Ingestion of excessive Cl^– accompanies the use of an ammonium chloride diuretic.
4. Usually, no specific symptoms are associated with chloride excess.
   1. There is lethargy and weakness.
   2. Deep breathing.

What are the causes of increased levels of Blood Chloride (Cl^–) (Hyperchloremia)?

1. urinary tract obstruction, glomerulonephritis, renal tubular acidosis, and acute renal failure.
2. Diabetes Insipidus.
3. Salicylate intoxication.
4. Prolonged diarrhea with the loss of sodium bicarbonate.
5. Respiratory alkalosis.
6. Some cases of primary hyperparathyroidism.
7. Maybe because of excessive intake.
8. Eclampsia.
9. Cushing syndrome.
10. Renal tubular acidosis.
11. Dehydration.
12. Due to the excessive infusion of normal saline.
13. Hyperventilation.

What are the causes of decreased levels of Blood Chloride (Cl^–) (Hypochloremia)?

1. Excessive sweating.
2. Prolonged vomiting.
3. Gastric suction.
4. Salt-losing nephritis.
5. Addisonian crises.
6. Metabolic acidosis is associated with increased organic anions.
7. Aldosteronism.
8. Respiratory acidosis.
9. Water intoxication.
10. Diuretic therapy.
11. Hypokalemia.
12. Burn
13. Overhydration.

How will you summarize serum electrolytes in various conditions?

How will you summarize electrolytes in Acidosis and alkalosis?

What are the critical values of chloride in serum or plasma?

• High value = >115 meq/L.
• Low value = <80 meq/L.

Questions and answers: