The human body maintains a delicate acid-base balance, measured by pH. Blood pH typically remains within a narrow, slightly alkaline range (7.35-7.45) for optimal bodily function. Deviations, either too acidic (acidosis) or too alkaline (alkalosis), can disrupt these functions and affect overall health.
Vomiting and Metabolic Alkalosis
Vomiting most commonly leads to metabolic alkalosis, where the blood becomes overly alkaline. This occurs primarily due to the significant loss of hydrochloric acid (HCl) from the stomach, a highly acidic fluid produced by stomach cells.
When hydrochloric acid is secreted into the stomach, bicarbonate ions are simultaneously released into the bloodstream. Normally, this bicarbonate is neutralized when stomach contents enter the small intestine. However, vomiting expels stomach acid before this neutralization occurs, leaving excess bicarbonate in the bloodstream and causing metabolic alkalosis.
Prolonged or severe vomiting also contributes to fluid loss and dehydration, which can further concentrate bicarbonate in the blood. Additionally, the loss of chloride through vomit (hypochloremia) can hinder the kidneys’ ability to excrete excess bicarbonate, perpetuating the alkaline state.
When Vomiting Can Lead to Acidosis
While metabolic alkalosis is the usual outcome, vomiting can less commonly lead to acidosis. One scenario involves the loss of bicarbonate-rich fluids from the lower gastrointestinal tract, such as severe diarrhea occurring concurrently with vomiting. In such cases, bicarbonate loss can outweigh stomach acid loss, leading to metabolic acidosis.
Acidosis might also be observed when vomiting occurs with an underlying condition causing excessive acid production. For example, diabetic ketoacidosis (DKA) is a serious diabetes complication where the body produces high levels of acidic ketones. Vomiting is a common DKA symptom, but the overwhelming systemic acidosis from ketone buildup dominates the acid-base balance.
Furthermore, severe dehydration caused by prolonged vomiting can lead to lactic acidosis. When the body experiences significant fluid loss, blood flow to tissues can be reduced, leading to poor oxygen delivery. Cells then switch to anaerobic metabolism, producing lactic acid as a byproduct, which can acidify the blood. In these instances, the acidosis is not directly caused by the loss of stomach contents but rather by the body’s response to severe fluid and electrolyte disturbances or pre-existing metabolic issues.
Recognizing Signs of Imbalance
Significant acid-base imbalances from vomiting can manifest through various symptoms. Metabolic alkalosis often involves electrolyte disturbances, particularly low levels of potassium and chloride. Symptoms can include muscle weakness, cramps, or spasms, ranging from mild discomfort to severe twitching or tetany.
Beyond muscular symptoms, individuals might experience neurological signs such as dizziness, lightheadedness, or confusion. In some instances, severe alkalosis can affect the central nervous system, leading to lethargy, disorientation, or even seizures. Changes in breathing patterns may also occur as the body attempts to compensate for the pH imbalance, though these might not always be overtly noticeable.
It is important to remember that some people with mild metabolic alkalosis may not exhibit clear symptoms, or their symptoms might be primarily related to the underlying cause of the vomiting. However, the presence of any of these signs, especially if they are worsening or persistent, indicates a need for medical evaluation to determine the extent of the imbalance.
Knowing When to Seek Medical Help
Persistent or severe vomiting, particularly when accompanied by other concerning symptoms, warrants professional medical attention. You should consult a healthcare provider if vomiting lasts for more than a day or two in adults, or if you are unable to keep any fluids down. Signs of severe dehydration, such as excessive thirst, dry mouth, infrequent urination, or dark-colored urine, also indicate a need for medical assessment.
Immediate medical attention is necessary if vomiting is accompanied by severe abdominal pain, chest pain, or a sudden, intense headache. Other red flags include confusion, altered mental status, or if the vomit contains blood, resembles coffee grounds, or is green. Individuals with underlying chronic health conditions, such as diabetes, should be particularly vigilant, as vomiting can quickly lead to serious complications like diabetic ketoacidosis.