Osmolal Gap, Serum Test Cost & Procedure

Osmolal gap serum is determined by calculating the difference between Measured Serum osmolality and calculated serum osmolality.

Why is this test conducted

Osmolal gap serum is conducted to detect the ingestion of toxins by our body, such as methanol or ethanol.

It also helps evaluate the water and electrolyte balance of our bodies.

Also used for the investigation of low sodium levels in our blood

When this test is conducted

This test is conducted when there is an ingestion of ethanol and methanol or when our body has low blood sodium levels.

Calculation of Osmolal Gap Serum

Osmolal Gap is equal to the Measured Serum osmolality -calculated serum osmolality.

Calculated osmolality = 2 x Na + Glucose + Urea (in mmol/L)

An average osmol gap is < 10 mOsm/kg

Osmolality

Osmolality is referred to the concentration of dissolved particles of minerals and chemicals such as sodium and other electrolytes present in the serum.

Higher osmolality is considered when there is an increase in the particles in the serum. Lower osmolality is considered when the particles present in the serum are more diluted.

Osmolality is increased when there are fewer drinking fluids(dehydrated), and it tends to decrease when there is an increase in the consumption of juices.

If there is less consumption of fluids in our body, there is an increase in the concentration of chemicals in our body, and thus, there is an increase in osmolality.

When there is more consumption of fluids in our body, it may lead to low blood sodium.

Water balance is an essential process that is regulated by regulating the number of fluids consumed by our body and regulated by controlling the amount of water in the urine, which is eliminated by the kidneys.

High serum osmolality

When there is an increase in the

Osmolality in the blood, there is a release of antidiuretic hormone (ADH) by our body. This results in more concentration in urine. The reabsorbed water thus starts diluting the blood.

What affects the serum Osmolality

The serum osmolality is affected by-

•  Proteins
• Sugars
• Glucose

What are the Causes of elosmolalOsmolal gap-

• Renal failure
• Shock
• Alcoholic ketoacidosis
• Diabetic Ketoacidosis