Metabolic Alkalosis Clinical Presentation
- Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FACP, FASN more...
Symptoms of metabolic alkalosis are not specific. Because hypokalemia is usually present, the patient may experience weakness, myalgia, polyuria, and cardiac arrhythmias.
Hypoventilation develops because of inhibition of the respiratory center in the medulla. Symptoms of hypocalcemia (eg, jitteriness, perioral tingling, muscle spasms) may be present.
The clinical history is helpful in establishing the etiology. Important points in the history include the following:
Vomiting or diarrhea - Gastrointestinal (GI) losses of hydrochloric acid (HCl)
Age of onset and family history of alkalosis - Familial disorders (eg, Bartter syndrome, which starts during childhood)
Renal failure - Alkali-loading alkalosis develops only when impairment of renal function occurs
Drug use (eg, loop or thiazide diuretics; licorice; tobacco chewing; carbenoxolone; fludrocortisone; glucocorticoids; antacids [eg, magnesium hydroxide]; calcium carbonate)
The physical signs of metabolic alkalosis are not specific and depend on the severity of the alkalosis. Because metabolic alkalosis decreases ionized calcium concentration, signs of hypocalcemia (eg, tetany, Chvostek sign, Trousseau sign), change in mental status, or seizures may be present.
Physical examination is helpful to establish the cause of metabolic alkalosis. Important aspects of the physical examination include the evaluation of hypertension and of volume status.
Hypertension accompanies several causes of metabolic alkalosis (see Etiology). Volume status assessment includes evaluation of orthostatic changes in blood pressure and heart rate, mucous membranes, presence or absence of edema, skin turgor, weight change, and urine output. Volume depletion usually accompanies chloride-responsive alkalosis, while volume expansion accompanies chloride-resistant alkalosis.
Because patients with bulimia frequently self-induce vomiting, they may have erosions of teeth enamel and dental caries because of repeatedly exposing their teeth to gastric acid.
Findings associated with Cushing syndrome include the following:
Violaceous skin striae
Congenital adrenal hyperplasia
Congenital adrenal hyperplasia (CAH): Infants with CAH secondary to 11-hydroxylase deficiency have hypertension and growth retardation. Male infants have premature sexual development, while female infants develop virilization. In 17-hydroxylase deficiency, males develop sexual ambiguity, while females have sexual infantilism.
Alkalosis may lead to tetany, seizures, and decreased mental status. Metabolic alkalosis also decreases coronary blood flow and predisposes persons to refractory arrhythmias. Metabolic alkalosis causes hypoventilation, which may cause hypoxemia, especially in patients with poor respiratory reserve, and it may impair weaning from mechanical ventilation. By increasing ammonia production, it can precipitate hepatic encephalopathy in susceptible individuals.
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