Diagnostic Yield of Critical Sample and Elective Fast-Test in Children After a Hypoglycemic Event: Experience From a Single Center in Israel.

Objective: To determine the diagnostic yield of the critical sample and fast-tests as dynamic function tests for the work-up of hypoglycemia in children.
Methods: A retrospective record review of children (0-18 years) with a diagnosis of hypoglycemia (glucose ≤ 50 mg/dL) was performed. A comparison of results of critical sample (obtained during an episode of hypoglycemia) and fast-test (performed to induce hypoglycemia in fasting state) was done.
Results: In 317 patients with hypoglycemia, data of 89 critical samples and 52 fast-tests were taken. Only 7 (7.8%) patients who underwent critical sample testing received an endocrine or metabolic diagnosis. No confirmatory diagnoses were made using the fast-tests. Idiopathic ketotic hypoglycemia was detected in 33/89 (37.1%) of critical samples and 21/52 (40.4%) of fast-tests. The completeness of workup including the hormonal and metabolic profile was <80% in both tests.
Conclusion: The confirmatory yield of critical sample was better than fast-test. The processing of metabolic analytes was incomplete in a few, suggesting the need to rationalize the dynamic function testing.