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.

Trough Concentrations of Specific Antibodies in Primary Immunodeficiency Patients Receiving Intravenous Immunoglobulin Replacement Therapy.

Immunoglobulin replacement therapy is a mainstay therapy for patients with primary immunodeficiency (PID). The content of these preparations was studied extensively. Nevertheless, data regarding the effective specific antibodies content (especially in the nadir period), and, in different groups of PID patients is limited. We studied trough IgG concentrations as well as anti-Pneumococcus, anti-Haemophilus influenzae b, anti-Tetanus, and anti-Measles antibody concentrations in 17 PID patients receiving intravenous immunoglobulin (IVIg) compared with healthy controls matched for age and ethnicity. We also analyzed these results according to the specific PID diagnosis: X-linked agammaglobulinemia (XLA), combined immunodeficiency (CID), and ataxia telangiectasia (AT). We recorded a higher concentration of anti-pneumococcal polysaccharide antibodies in healthy controls compared to the entire group of PID patients. We also found significantly higher anti-tetanus toxoid antibody concentrations in the XLA patients, compared to CID patients. Anti-Haemophilus Influenzae b antibody titers were overall similar between all the groups. Interestingly, there were overall low titers of anti-Measles antibodies below protective cutoff antibody concentrations in most patients as well as in healthy controls. We conclude that relying on total IgG trough levels is not necessarily a reflection of effective specific antibodies in the patient's serum. This is especially relevant to CID patients who may have production of nonspecific antibodies. In such patients, a higher target trough IgG concentration should be considered. Another aspect worth considering is that the use of plasma from adult donors with a waning immunity for certain pathogens probably affects the concentrations of specific antibodies in IVIg preparations.