What percentage of the body weight is water? What is meant by the terms ICF and ECF?

Composition of body fluid. Healthy adults of the body water comprises of 60% of the body weight that exists into compartments. Intracellular compartments (present within cells) is called as the ICF contains of the 2/3rd of body water or 40% of body weight. The extra cellular( present outside cells) or ECF contains 1/3rd of the total body. Blood constitutes 1/3rd of the ECF volume.

What are the main electrolytes in the human body?

The human body mainly consists of the following electrolytes: sodium, potassium, chloride, bicarbonate phosphate, and sulphates. These electrolytes are so distributed that some are predominantly within the cells while others are predominantly outside the cells.

Sodium, chloride and bicarbonate are mainly extra cellular and thus constitute the principal solutes of the ECF. Potassium is the principal cation of intracellular fluid and 98% of the body potassium is intracellular. The principal anions of the intracellular fluid vary and they usually include phosphates, sulphates and negatively charged micro molecules.

What is meant by volume depletion?

Loss of fluid or blood from the body is called volume depletion. Seen in loss of blood due to hemorrhage, loss of fluid from vomiting, diarrhea, or loss of excess water from the urine as with diuretics.

How do patients with volume depletion present?

The clinical manifestation depends on the degree and rapidity of the fluid that is lost. If it is mild the patients just exhibits some giddiness, weakness, increased thirst, dryness of mouth. If it is more advanced it can result in decreased blood pressure and urine output.

Are there any means to accurately measure the volume status of a person?

Usually in sick patients in the ICU catheters are inserted into the heart to directly monitor pressures such as the central venous pressure, the pulmonary capillary wedge pressure etc. These parameters provide a more accurate method to monitor the volume status.

How is volume depletion treated?

The treatment of volume contraction is by replacing the appropriate fluid. Blood is used when there is hemorrhage. Albumin and plasma infusions can be used in emergency situations. Solutions containing sodium (Normal saline, Ringer Lactate) are used in situations such as vomiting, diarrhea.

What is Hyponatraemia?

Low level of sodium in the blood is called hyponatraemia. Normal level is 140 meq/lL.

What are the causes of Hyponatraemia?

Hyponatraemia is seen when there is loss of sodium or excess water in the body which dilutes the sodium.

1. Loss of sodium as in diarrhea
2. Loss of sodium from the kidney as with diuretics
3. Excess water retention as seen in heart or kidney failure.
4. SIADH (Syndrome of Inappropriate ADH production)

Is Hyponatraemia dangerous?

Symptoms of hyponatraemia depends on the rapidity with which sodium level drops. Usually patients present with confusion, and sometimes even seizures, coma and death, if levels are too low.

What is Hypernatremia?

Hypernatraemia is characterized by increased sodium level in the blood. It is more a disorder of water metabolism and is seen when the ratio of solutes to water in the body is increased.

What are the causes of Hypernatremia?

1. Impaired thirst e.g.: coma
2. Presence of osmotic substances in the urine which cause excessive water loss. e.g. glucose, mannitol administration, diabetic ketoacidosis.
3. Excess loss of water from the kidney as in diabetes insipidus.
4. Excess loss of water from the skin: e.g. sweating, burns.

How much potassium is present in the body?

The human body contains 3500 meq of potassium majority of which is in the cells.

What is Hyperkalemia?

Abnormal elevation of potassium in the blood is called hyperkalemia. Normal potassium level is between 3.5 to 4.5 meq per liter. A level greater than 4.5meq/L is called Hyperkalemia.

What are the major causes of Hyperkalemia?

1. It can result from decreased excretion from the kidneys as in renal failure
2. Drugs such as potassium sparing diuretics (e.g. spironolactone)
3. Trans cellular shifts i.e. the potassium tends to move out of the cells. Seen in a condition called acidosis (low pH of blood).

How do patients present if they have Hyperkalemia?

1. Limb weakness.
2. Abnormal heart rhythms which can be fatal if the level is very high. The ECG usually shows tall T waves.

What is the treatment for Hyperkalemia?

1. In emergent condition calcium is given intravenously to protect the heart from high potassium.
2. Insulin and glucose is given intravenously. The insulin drives the potassium into the cell.
3. Cationic exchange resins such as polysterene sulfonate( Kayexalate) can be given orally or rectally.
4. Hemodialysis is used in renal failure patients.

The appropriate cause of Hyperkalemia should be sought.

What is hypokalemia?

When the serum potassium level goes below 3.5 meq/L it is called hypokalemia.

What are the causes of hypokalemia?

1. Inadequate intake.
2. Excessive loss of potassium from the kidney can occur with diuretics, antibiotics harmful to the kidney such as amphotericin and gentamicin.
3. Gastrointestinal loss from vomiting, diarrhea.
4. Excess loss from skin as in burns.