Final answer:
An increase in osmolal gap can be caused by the presence of abnormal substances in the blood or a decrease in the concentration of normal osmotically active substances.
Step-by-step explanation:
An increase in osmolal gap can be caused by several factors. One common cause is the presence of substances in the blood that are not normally present, such as ethanol or methanol. These substances can increase the osmolality of the blood, leading to an increase in osmolal gap. Another possible cause is the presence of abnormal substances in the blood, such as ketones in diabetic ketoacidosis. These substances can also increase the osmolality of the blood and contribute to an increased osmolal gap.
In addition, an increase in osmolal gap may be seen in conditions that cause a decrease in the concentration of normal osmotically active substances in the blood, such as hypoalbuminemia. This can occur in conditions like liver disease or malnutrition. When the concentration of these substances decreases, the osmolality of the blood decreases as well, resulting in an increased osmolal gap.
In summary, an increase in osmolal gap can be caused by the presence of abnormal substances in the blood or a decrease in the concentration of normal osmotically active substances.