Background
Hypochloremic alkalosis is common in hospitalized children and is rare in outpatient settings. In neonatal ICUs (NICUs), this form of alkalosis frequently results from diuretic therapy for bronchopulmonary dysplasia. Hypochloremic alkalosis due to loss of gastric acid via nasogastric tube suctioning is also common in pediatric ICUs. Other rare, but serious, causes must be considered in any child presenting with failure to thrive, poor development, and a family history of neonatal demise and metabolic alkalosis in the absence of diuretic or laxative abuse. Repeated vomiting may be a clue that the patient has severe gastroesophageal reflux or pyloric stenosis.
History of polyhydramnios is helpful; polyhydramnios may result from polyuria or congenital diarrhea. A lack of both symptoms may help identify cystic fibrosis. Severe hypochloremic metabolic alkalosis may be the presenting metabolic derangement for multiple conditions. Molecular diagnostic procedures sometimes help resolve differential diagnoses. Severe brain damage and psychomotor retardation may occur in children with delayed diagnosis and treatment.
Pathophysiology
Hypochloremic alkalosis results from either low chloride intake or excessive chloride wasting. Low chloride intake is very uncommon. Excessive chloride wasting often occurs in hospitalized children, usually due to diuretic therapy or nasogastric tube suctioning. Chloride-wasting syndromes, including Bartter syndrome, congenital chloride-losing diarrhea (CLD), and cystic fibrosis, result from renal tubular loss, defective electrolyte transport across intestinal epithelia, or chloride loss via the skin, respectively.
Epidemiology
Frequency
International
Frequency of hypochloremic alkalosis is unknown, both in the United States and worldwide.
Mortality/Morbidity
Anorexia and polyuria eventually lead to malnutrition and growth failure. Chronic dehydration frequently causes constipation. A small muscle mass and muscle wasting are frequently seen in patients following a late diagnosis or in untreated patients.
CNS effects include cerebral dysfunction and defective cognitive function resulting from chronic hypoperfusion in moderate-to-severe metabolic alkalosis due to hypokalemic and hypochloremic states. Hypopnea is due to depression of respiratory drive. CNS calcification occurs in some patients for unclear reasons. Seizure disorder, brain atrophy, and mental retardation are other known sequelae.
Depending on the renal disorder, complications may include nephrocalcinosis, interstitial nephropathy, hypercalcemia, hyperuricemia, hypertension during the late stages of renal damage, and renal failure.
Race
Hypochloremic alkalosis may be more common worldwide than previously accepted. Many cases of CLD have emerged from Eastern Europe and Middle Eastern Arab countries; indeed, the largest purported series arose from Saudi Arabia.[1] Fewer cases in the English language literature have been reported in the Far East and North America, perhaps because of cultural and academic barriers.
Sex
Males and females are affected in equal numbers.
Age
CLD can manifest before birth as severe midtrimester polyhydramnios. Metabolic derangements may manifest as early as the first few days of life. Bartter syndrome may present at any age but primarily occurs in infants younger than 1 year. Hypochloremic alkalosis resulting from cystic fibrosis is infrequent in infancy but can become more severe in summer because of excessive chloride loss from sweating. Drug-related hypochloremic alkalosis is observed at all ages.
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