Pediatric Metabolic Alkalosis Workup
- Author: Lennox H Huang, MD, FAAP; Chief Editor: Timothy E Corden, MD more...
Measurements of blood gas and serum electrolyte levels, including calcium, are the essential laboratory studies necessary for initial evaluation of metabolic alkalosis. An algorithm for metabolic alkalosis is shown in the image below.
Blood Gas Measurement, Serum Electrolyte levels, and Spot Urine Chloride
Blood gas measurement shows elevated pH with a high HCO3 level. With compensation, the PCO2 level may also be near the reference range or elevated.
Serum electrolyte levels may show evidence of hypokalemia, hypercalcemia, hypochloremia, or hyponatremia.
A urine chloride level of less than 10 mEq/L indicates chloride-responsive metabolic alkalosis. A urine chloride level of more than 20 mEq/L indicates chloride-resistant metabolic alkalosis.
Diagnostic Indicators for Specific Disease States
Patients with primary aldosteronism have metabolic alkalosis, hypokalemia, a urine chloride level of more than 20 mEq/L, and persistently elevated aldosterone levels despite controlled sodium chloride (NaCl) intake of 12-15 g daily for 5 days.
Cushing syndrome is marked by hypersecretion of cortisol.
Primary reninism usually results from renovascular disease with hypertension.
Bartter syndrome manifests as hypokalemic metabolic alkalosis with secondary hyperaldosteronism and with renal potassium and chloride wasting.
Milk-alkali syndrome results from excessive oral intake of calcium, vitamin D metabolites, and absorbable alkali. Metabolic alkalosis in these patients is usually accompanied by hypercalcemia.
Pyloric stenosis causes marked hypochloremia (due to loss of HCl in gastric contents) and metabolic alkalosis. It is generally observed in male infants aged approximately 6-12 weeks. These patients present with protracted vomiting and frequently have significant dehydration and cachexia.
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